United States

Department of

Agriculture

Forest Service

Northeastern

Research Station

General Technical

Report NE-311

Edited by:

Michael L. McManus

Andrew M. Liebhold

Kraków, Poland

September 1-5, 2002

Proceedings

Ecology, Survey and

Management of Forest Insects
Published by: For additional copies:

USDA FOREST SERVICE USDA Forest Service

11 CAMPUS BLVD SUITE 200 Publications Distribution

NEWTOWN SQUARE PA 19073-3294 359 Main Road

Delaware, OH 43015-8640

November 2003 Fax: (740)368-0152

Cover

The photographs on the cover (from the upper left corner going clockwise) are (photographer’s

name in parentheses): Leaf damage caused by the horse-chestnut leafminer, Cameraria

ohridella (Gyuri Csóka), gypsy moth, Lymantria dispar late instar larva with eggs of the

parasitoid, Parasetigena silvestris (Gyuri Csóka), extensive tree mortality caused by Ips

typographus outbreak, Tatra National Park, Poland (Rose-Marie Muzika), and galleries of Ips

typographus (Milos Knizek).

Most of the papers in this publication were submitted electronically and were edited to

achieve a uniform format and typeface. Each contributor is responsible for the accuracy and

content of his or her own paper. Statements of the contributors from outside the U.S.

Department of Agriculture may not necessarily reflect the policy of the Department. Some

participants did not submit papers so they have not been included.

The use of trade, firm, or corporation names in this publication is for the information and

convenience of the reader. Such use does not constitute an official endorsement or approval

by the U.S. Department of Agriculture or the Forest Service of any product or service to the

exclusion of others that may be suitable.

Remarks about pesticides appear in some technical papers contained in these proceedings.

Publication of these statements does not constitute endorsement or recommendation of them

by the conference sponsors, nor does it imply that uses discussed have been registered. Use

of most pesticides is regulated by State and Federal Law. Applicable regulations must be

obtained from the appropriate regulatory agencies.

CAUTION: Pesticides can be injurious to humans, domestic animals, desirable

plants, and fish and other wildlife - if they are not handled and applied properly.

Use all pesticides selectively and carefully. Follow recommended practices given on the label

for use and disposal of pesticides and pesticide containers.

Manuscript received for publication 22 July 2003

For an online version:

www.fs.fed.us/ne/newtown_square/publications/technical_reports/pdfs/2003/gtrne311.pdf
Proceedings

Ecology, Survey and Management of Forest Insects1

Kraków, Poland

September 1-5, 2002

Edited by:

Michael L. McManus

USDA Forest Service, Northeastern Research Station, 51 Mill Pond Rd.,

Hamden, CT 06514-1703, USA

Andrew M. Liebhold

USDA Forest Service, Northeastern Research Station, 180 Canfield St.,

Morgantown, WV 26505, USA

Published by

USDA Forest Service

Northeastern Research Station

General Technical Report NE-311

2003

1

A meeting sponsored by the International Union of Forestry Research Organizations (IUFRO) Working Party

S7.03-06, “Integrated Management of Forest Defoliating Insects,” and Working Party S7.03.07, “Population

Dynamics of Forest Insects.”
Preface

These proceedings result from a conference, “Ecology, Survey and Management of Forest

Insects” held at the Congress Centre, Agricultural Academy in Kraków, Poland, 1-5

September, 2002. This meeting was hosted by the Agricultural Academy in Kraków and the

Forest Research Institute, Warsaw and sponsored by IUFRO units 7.03.06 “Integrated

management of forest defoliating insects”, 7.03.07 “Population dynamics of forest insects”,

and 7.03.10 “Methodology of forest insect and disease survey in Central Europe.” The joint

meeting was a great success and demonstrated the value of holding combined meetings

among these three groups.

Local arrangements for the meeting were organized by Dr. Wojciech Grodzki, Forest Research

Institute Warsaw, Department of Forest Management in Mountain Regions in Kraków. Dr.

Grodzki did an excellent job of coordinating the meeting and organizing an informative and

enjoyable field trip to the Tatra National Park to observe extensive damage caused by Ips

typographus, and to managed forests in Podhale Upland, to view damage caused by wind and

floods and related forest protection problems. Photographs taken during the meeting can be

viewed on the Internet at http://iufro.boku.ac.at/iufro/iufronet/d7/wu70310/krakow/report.

Seventy-four delegates from 22 countries attended the meeting. There were 33 oral and 28

poster presentations. Delegates presented a broad array of topics and included methods for

surveying forest insects, population dynamics of forest insects, effects of insects and diseases

in forest ecosystems, integrated management and biological control of forest insects.

Submission of a paper for inclusion in these proceedings was optional.

The success of an international conference such as this requires the assistance of many

individuals, therefore we would like to recognize Wojciech Grodzki and colleagues from the

Forest Research Institute, Kraków and Jerzy R. Starzyk and his staff at the Agricultural

Academy of Kraków for organizing an excellent meeting. Their efforts in coordinating local

arrangements and facilitating the field trip were outstanding and resulted in a truly

memorable experience for all participants. We thank Director Pawel Skawiński and his staff

at the Tatra National Park in Zakopane for hosting our group for that portion of the field

trip, and Chief Forester Roman Latoń and his staff, State Forests, Forest Inspectorate Nowy

Targ, for hosting the remainder of the field trip and evening party in the forest.

The USDA Forest Service Northeastern Research Station and the USDA Forest Service

Forest Health Technology Enterprise Team sponsored the publication of these proceedings

and we thank them for making this volume possible. The editors are indebted to Barbara

Johnson for her assistance in preparing the manuscripts for these proceedings.
Contents

The Attack of Aesculus hippocastanum L. by Cameraria ohridella Deschka and Dimic

(Lepidoptera: Gracillariidae) in Greece ...................................................................................................... 1

Nikolaos Avtzis, Dimitrios Avtzis

New Lure for the Larger Pine Shoot Beetle, Tomicus piniperda — Attractant/Trap Design

Combinations Tested in North America and Europe ................................................................................. 6

D. Czokajlo, B. Hrašovec, M. Pernek, J. Hilszczanski, A. Kolk, S. Teale, J. Wickham, P. Kirsch

Bark Beetle Management After a Mass Attack — Some Swiss Experiences ............................................... 10

B. Forster, F. Meier, R. Gall

Integrated Management of Little Spruce Sawfly (Pristiphora abietina): Design Pattern ............................. 16

J. Holusa, K. Drápela

Definition of Spatial Patterns of Bark Beetle Ips typographus (L.) Outbreak Spreading in Tatra

Mountains (Central Europe), Using GIS ................................................................................................. 25

Rastislav Jakuš, Wojciech Grodzki, Marek Ježík, Marcin Jachym

The Population and Seasonal Dynamics of Weevils Developing in the Soil of Birch Stands ..................... 33

E. Kula

Spread and Character of Tomostethus nigritus F. Outbreaks in Croatia During the Last Decade ................ 39

Dinka Matošević, Boris Hrašovec, Milan Pernek

Microsporidian Pathogens in European Gypsy Moth Populations ........................................................... 44

Michael L. McManus, Leellen Solter

Dependency of Outbreaks Distribution from Insects-defoliators’ Seasonal Development ........................ 52

Valentina Meshkova

Dynamics of Foci of Forest Pest Insects in Russia over the Last Decade .................................................. 61

E.G. Mozolevskaya, I. A. Utkina, L. S. Matusevich

Host-plant Relationships and Comparative Ecology of Conifer-feeding Budworms

(Choristoneura spp.) ................................................................................................................................. 68

V.G. Nealis

Monitoring and Risk Assessment of the Spruce Bark Beetle, Ips typographus............................................. 75

S. Netherer, J. Pennerstorfer, P. Baier, E. Führer, A. Schopf

“Sterile Insect Technique” as a Tool for Increasing the Efficacy of Gypsy Moth Biocontrol ...................... 80

Július Novotný, Milan Zúbrik

Beetle Fauna Captured in Traps Baited with Tomicis piniperda Pheromone Blends in a Pine Stand

in Central Croatia .................................................................................................................................... 87

Milan Pernek, Boris Hrašovec, Miljenko Županič

Interrelations of Green Oak Leaf Roller Population and Common Oak: Results of 30-year

Monitoring and Mathematical Modeling ................................................................................................. 90

V.V. Rubtsov, I.A. Utkina

Host-tree Preferences of the Pine Moth (Lepidoptera: Lasiocampidae) and Pine Beauty Moth

(Lepidopera: Noctuidae) Larvae in Relation to Needle Quality ................................................................ 98

Lidia Sukovata, Andrzej Kolk, Jadwiga Jaroszynska, Urszula Krajewska,

Agnieszka Purzynska, Valerii Isidorov
Radial Growth Rate and Susceptibility of Picea rubens Sarg. to Tetropium fuscum (Fabr.). ...................... 107

K. O’Leary, J.E. Hurley, W. Mackay, J. Sweeney

Preliminary Results on Predation of Gypsy Moth Egg Masses in Slovakia .............................................. 115

Marek Turčáni, Andrew Liebhold, Michael McManus, Július Novotný

The Role of Selected Soil Fauna as Predators of Apethymus abdominalis Lep. (Hymenoptera:

Tenthredinidae) in Oak Forests in the District Căiuţi, Romania ............................................................ 121

C. Ciornei, N. Popa, L. Ciucă, C. Rang

Parasitoid Communities of Two Invading Leafminers of Black Locust in Hungary: First Year Results.... 123

György Csóka, Anikó Hirka, George Melika

InterceptTM Panel Trap (INT PT) Effective in Management of Forest Coleoptera ................................. 125

D. Czokajlo, J. McLaughlin, L.I. Abu Ayyash, S. Teale, J. Wickham, J. Warren,

R. Hoffman, B. Aukema, K. Raffa, P. Kirsch

Imaginal Diapause in the Bark Beetle, Ips typographus ............................................................................ 127

Petr. Doležal, František Sehnal

Xylobios: Patterns, Roles and Determinants of Saproxylic Diversity in Belgian Deciduous Forests ........ 128

Philippe Fayt, Etienne Branquart, Marc Dufrene, Jean-Marc Henin, Christophe Pontegnie,

Veerle Versteirt

Reproduction of a Woodwasp, Urocerus japonicus (Hymenoptera: Siricidae) Using No Maternal Symbiotic

Fungus ................................................................................................................................................... 130

Hideshi Fukuda

Spatial Patterns of First Spruce Bark Beetle (Ips typographus L.) Infestation of Standing

Norway Spruce (Picea abies [L.] Karst.) After Heavy Storm Damage in Switzerland .............................. 132

R. Gall, A. Heimgartner

Trypodendron domesticum and Trypodendron signatum: Two Scolytid Species Involved

in Beech Decline in Belgium.................................................................................................................. 134

B. Gaubicher, M. De Proft, J.-C. Gregoire

Forest Litter Insect Community Succession in Clearcuts of Norway Spruce........................................... 136

Art ̄uras Gedminas

Qualitative Survey of Five Beech-Damaging Coleoptera

(Scolytidae and Lymexylonidae) in Wallonia (Southern Belgium) .......................................................... 138

Jean-Marc Henin, Olivier Huart, Philippe Lejeune, Jacques Rondeux

Management of Shoot Boring Moths from Genera Rhyacionia and Eucosma with Attract and

Kill Technology...................................................................................................................................... 141

R. Hoffman, D. Czokajlo, G. Daterman, J. McLaughlin, J. Webster, R. Rynearson,

M. Gray, A. Eglitis, C. Jensen, B. Hughes, P. Flanagan, L. Spiegel, W. Berisford, C. Asaro

S. Cameron, J. Seckinger, L. Sukovata, A. Kolk, W. Strong, P. Kirsch

Fire as a Tool in Restoring and Maintaining Beetle Diversity in Boreal Forests: Preliminary

Results from a Large-scale Field Experiment .......................................................................................... 144

E. Hyvärinen, H. Lappalainen, P. Martikainen, J. Kouki

Location, Evolution and Importance of Cephalcia spp. (Hym: Pamphiliidae) Populations in

Polish Carpathian Mountains ................................................................................................................ 145

Marcin Jachym
Methods Used for Investigating the Incidence of Phytophthora Disease of Alder in Hungary.................. 147

A. Koltay, J. Bakonyi, Z.Á. Nagy

Migration Features of Ips typographus in the Tatra Mountains: Using a Genetic Method ........................ 150

Ferenc Lakatos

Braconid (Hymenoptera: Braconidae) Parasitoids of Bark Beetles in Upland Spruce Stands

of the Czech Republic ............................................................................................................................ 152

Aurel Lozan, Jiří Zelený

Effect of Aerial Sprays on the Abundance of Litter Insects ..................................................................... 154

J ̄urate Lynikien  ̇ e, Paulius Zolubas  ̇

Bark Beetles (Scolytidae: Coleoptera) in Slovenia with Special Regard to Species in Burnt

Pine Forests............................................................................................................................................ 157

Maja Jurc

Phenological Prediction of Forest Pest Defoliators ................................................................................. 160

Valentina Meshkova

The Frequency and Intensity of Bark Beetle Infestations Recorded in Romanian Forests Affected

by Windfall in 1995............................................................................................................................... 162

V. Mihalciuc, A. Danci, M. Bujilă, D. Chira

Dendrochronological Analysis of Trees and Stands Attacked by Dendroctonus ponderosae

in Colorado ........................................................................................................................................... 165

José F. Negrón and John Popp

Insects in IBL-4 Pine Weevil Traps ......................................................................................................... 166

I. Skrzecz

Ips typographus (L.) (Coleoptera: Scolytidae) in Southeastern Alps: Results of a Six-Year-Long

Monitoring Program .............................................................................................................................. 168

F. Stergulc, M. Faccoli

Biotic Agents that Damage Black Locust in Hungary............................................................................. 170

József Tóth

Pine Shoot Beetles Blastophagus piniperda L. and B.minor Hart. Associated with Outbreaks of

the Pine Beauty Moth (Panolis flammea Schiff.) ..................................................................................... 171

Skirmantas Vaivada

Survey of Hylobius abietis (L.) and Associated Species in Reforestation Areas Using Baited

Pitfall Traps............................................................................................................................................ 173

Kaljo Voolma

Pheromone Traps and Other Methods in Assessing Pine Beauty Moth (Panolis flammea Schiff.) ........... 176

Algimantas Žiogas

Pine Beauty Moth (Panolis flammea Schiff.) Outbreak Management: Suppression Versus

Natural Enemies .................................................................................................................................... 178

Paulius Zolubas
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 1

Abstract

The horse chestnut leaf miner Cameraria ohridella is a relatively new insect in Europe, which was first

observed at Lake Ohrid in 1984. Within the framework of the European Community Project

“Controcam”, in which Greece participates through the TEI of Kavala, Department of Forestry in

Drama, we attempted for the first time to study the bio-ecology as well as the spread of this pest in

Greece.

By using pheromone traps and visiting different areas with the technical support of the Greek Forest

Service, it was possible to reach the following conclusions:

1. C. ohridella has at least three generations per year and there is a possibility for a fourth generation

2. It attacks horse chestnut when it occurs as natural stands of trees but it may also infest horse

chestnuts that are grown in artificial plantings.

3. C. ohridella has not been detected attacking Acer species in Greece.

Key words: Cameraria ohridella, Aesculus hippocastanum, Greece, spread, pheromone traps,

Acer-host plant

The horse chestnut leaf miner (Cameraria ohridella) was observed for the first time in Europe in 1984

when it was reported attacking horse chestnut trees at Lake Ohrid (Simova-Tosic and Filev 1985). In

1986, the leaf miner was identified by Deschka and Dimic as Cameraria ohridella, using the name of

the area where it was first discovered. In 1989, the insect was observed in Central Austria, about

1000 km north of the first point of attack (Puchberger 1995). Apparently the spread of C. ohridella

into Central and Eastern Europe occurred very rapidly (Freise and Heitland 1999); it was reported in

Germany (Butin/Führer 1994), Hungary (Szaboky 1997) in Czech Republic (Liska 1997) and

Slovakia (Sivicek et al. 1997). The spread of this insect in Greece was very slow, probably because of

the limited distribution of Aesculus hippocastanum (Skuhravy 1999).

Materials and Methods

Within the framework of the European Community Project named “Controcam,” in which Greece

participates through the Department of Forestry of the Technological Educational Institute of

Kavala, we attempted for the first time to study the spread as well as the bio-ecology of this particular

leaf miner in Greece. Prior to the start of the “Controcam” Project, the unique information known

about the status of C. ohridella in Greece was about the appearance of C. ohridella on two

A. hippocastanum ornamental trees at the mountain Pelion in Central Greece (Longitude: E 23o

 04.

459, Latitude: 39o 20. 810, Altitude: 605 ml) in1998 (Skuhravy, 1999). In order to satisfy the needs

of the Project mentioned above, we initiated a systematic study of this insect in Greece.

Development-Number of Generations

In order to study the development of C. ohridella and to determine the number of generations per

year, 10 “Delta” traps were set out during the first ten days of April 2001 at Grevena (Central

Greece). Traps were placed in the lower crown of 10 A. hippocastanum that were growing along a

stream at an altitude of 845 meters (Longitude: E 021o

 12. 060, Latitude: 39o 58. 073). The

The Attack of Aesculus hippocastanum L. by Cameraria ohridella

Deschka and Dimic (Lepidoptera: Gracillariidae) in Greece

 Nikolaos Avtzis1 and Dimitrios Avtzis2

1

Technological Educational Institute of Kavala Dep. of Forestry in Drama, 66 100 Drama-Greece

2

Std. at the Dept. of Forestry, Aristotelian University of Thessaloniki, Greece
2 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

pheromone dispenser was produced at the Institute of Organic Chemistry and Biochemistry,

Academy of Sciences of the Czech Republic.

Observations during the first season (2001) started at the beginning of April and finished at the end

of September. During this period of observations the dispenser of every trap was changed every

fourth week.

Every observation lasted 24 hours. That means that at the beginning of every observation every Delta

trap received a new sticky bottom, which was removed the next day, exactly 24 hours after its

installation.

In that way the number of the captured moths during the 24-hour observation period provided

information about the flight period of the adults as well as the fluctuations of their population intensity.

The dispenser was changed every fourth week and the period of observation lasted for 24 hours. This

means that at the beginning of every observation every trap receives a new sticky bottom, which is

removed the next day, in exactly 24 hours. Observations took place on the same trees in the same area

(Grevena) during 2002.

Spread

The spread of C. ohridella in Greece was studied by visiting locations throughout Greece with the

assistance of the local Greek Forest Service. Information including photographs and leaf samples were

collected from each location for further analysis. This work was conducted in 2001 and in 2002.

Host plants

A number of samples were taken monthly at the area of Grevena and Karitsa (Longitude: E 022o 45.

971, Latitude: 39o 48. 785, Altitude: 705 m), in order to search for evidence of infestation among the

different Acer species. These obseravtions began in 2001 (April-October) and were repeated in 2002.

The search was conducted in areas adjacent to heavily infested horse chestnut trees and included leaf

sampling of the following Acer species:

1. Acer obtusatum (Grevena)

2. A. monspessulanum (Grevena)

3. A. campestre (Grevena)

4. A. platanoides (Grevena)

5. A. pseudoplatanus (Karitsa)

Results and Discussion

The pheromone trap data indicate that C.

ohridella has three generations per year at

Grevena (Fig. 1).

This result agrees with published literature

which suggests that C. ohridella has 3-5

generations per year (Deschka and Dimic

1986, Pschorn-Walcher 1994, Skuhravy

1999). Based on observations during the

two years (2001-2002), the periodicity of

moth capture was similar during the first

generation in early May and the second

generation that peaked in early July.

Figure 1.—Total number of captures of C. ohridella from

ten pheromone traps at Grevena

0

500

1000

1500

2000

2500

3000

3500

(n)

3-4 Apr

17-18 Apr

1-2 May 

15-16 May29-30 May

12-13 Jun26-27 Jun

10-11 Jul24-25 Jul

7-8 Aug

21-22 Aug

4-5 Sept

18-19 Sept

2001

2002
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 3

However the peak flight period for the

third generation in 2002 was delayed by

approximately two weeks.

The explanation for the approximately

five times greater number of insects

captured in 2002 (19,828 moths) as

compared to 2001 (3,938 moths) may be

related either to the weather conditions or

to the complex of natural enemies that

occurred at the observation sites. Both of

these parameters will be investigated in

future years at Grevena.

There was an observed variation in the

number of C. ohridella that were captured

among the 10 trees at Grevena. In both

years, significantly more insects were captured on the same four trees (2,3,5,10) even though all trees

were growing under the same site conditions on a line of about 1,800 across the stream (Fig. 2). We

have no explanation for this, however we will continue to monitor populations in future years.

For the distribution of C. ohridella in Greece, results from two years of observations indicate that the

insect occurs at 36 locations. Among the 36 locations, 18 consisted of wild trees/stands and 18 were

ornamental plantings. The majority of those sites were located across the main mountain region of

Greece on a north-south axis as illustrated in Figure 3. All of the sites occurred at an Altitude of 520

to 1370 meters above sea level, at a Longitude from E 020°51 100 to E 023° 10.444, and at a

Latitude from N 38° 37 751 till 40° 50 683.

Observations to date indicate that:

1. The insect attacks wild as well as ornamental horse chestnut trees in parks, gardens and along

roads.

2. No difference was observed in the intensity of attacks from C. ohridella between wild and

ornamental trees. The infestation level after the flight of the adults of the second generation may

vary from a few mines per compound leave (0-5%) up to almost complete

infestation of leaflets with mines (more than 80% of the photosynthetic area per leave).

3. All the wild A. hippocastanum trees, wherever they were found in Greece, were attacked by

C. ohridella.

It has been suggested that second generation moths of C. ohridella may occasionally infest species of

Acer if there is a shortage of healthy A. hippocastanum foliage. Other authors reported development of

C. ohridella on the leaves of A. platanoides and A. pseudoplatanus (Krehan 1995, Pschorn-Walcher

1997, Skuhravy 1999). However, we did not find any infestation by C. ohridella on Acer foliage from

Grevena and Karitsa even if the infestation level on the adjacent A. hippocastanum trees was very high

(more than 80% of the total surface of the leaves). Other authors reported development of C.

ohridella on the leaves of A. platanoides and A. pseudoplatanus (Krehan 1995, Pschorm-Walcher 1997,

Skuhravy 1999).

So far, C. ohridella is not a serious problem in Greece because of the limited presence of A.

hippocastanum. However this situation may change in the future because in recent years, the horse

chestnut tree seems to be one of the most popular species for plantings in parks, gardens and along

avenues in many areas of Greece. In order to prevent this problem from worsening in the future, use

of the most resistant species (e.g. carnea) in plantings should be encouraged.

Figure 2.—Captures (%) of C.ohridella from ten pheromone

traps at Grevena

0.2 1.9

18.3

22.4

19.6

22.9

1.7 2.6

45.8

31.4

2.7 2.7

0.3

2.1 1.7 3.2

0.1 0.2

9.8 10.6

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

(%)

1 2 3 4 5 6 7 8 9 10

Number of traps

2001

2002
4 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

References Cited

Butin, H. und E. Führer. 1994. Die Kastanien-Miniermotte (Cameraria ohridella Deschka &

Dimic) an Aesculus hippocastanum. Nachrichtenbl. Deut. Pflanzenschutzd. 46 (5): 89-91.

Deschka, G. and N. Dimic. 1986. Cameraria ohridella sp. n. (Lep., Lithocolletidae) aus

Mezedonien. Acta Entomol. Jugosl. 22: 11-23.

Freise, J. and W. Heitland. 1999. A brief note on sexual differences in pupae of the horse-chestnut

leaf miner, Cameraria ohridella Deschka & Dimic (1986) (Lep., Gracillariidae), a new pest in

Central Europe on Aesculus hippocastanum. J. Appl. Ent. 123: 191-192.

Krehan, H. 1995. The horsechestnut leafmining moth Cameraria ohridella - incidence of attack in

Austria. Forstschutz Aktuell No. 16:8-11.

 Liska, J. 1997. Verbreitung der Roßkastanienminiermotte in der Tschechischen Republik.

Forstschutz-Aktuel, Wien 21: 5.

Pschorn-Walcher, H. 1994. Freiland–Biologie der eingeschleppten Roßkastanienminiermotte

Cameraria ohridella Deschka et Dimic (Lep., Gracillariidae) im Wienerwald. Linzer biol. Beiträge,

26/2: 633-642.

Pschorn-Walcher, H. 1997. Zur Biology und Populationsentwicklung der eingescleppten

Rosskastanien-Miniemotte, Cameraria ohridella. Forstschutz Aktuell. No. 21: 7-10.

Figure 3.—Localities in Greece where C. ohridella was found

attacking A. hippocastanum as of September, 2002
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 5

Puchberger, K.M. 1995. Zur Geschichte der ersten Ausbreitung von Cameraria ohridella Deschka &

Dimic 1986 in Österreich (Lepidoptera, Gracillariidae). Ent. Nacht. Blatt, Wien, 2 (1): 2-3.

Simova-Tosic, D. und S. Filev. 1985. Prilog poznavanju minera divljeg kestena (Contribution to

the Horse chestnut miner). Zastita Bilja (Belgrad) 36: 235-239.

Sivicek, P., P. Hrubik und G. Juhasova. 1997. Verbreitung der Roßkastanienminiermotte in der

Slovakei. Forstschutz-Aktuel, Wien 21: 6.

Skuhravy, V. 1999. Zusammenfassende Betrachtung der Kenntnisse über die Roßkastanienminiermotte, Cameraria ohridella Deschka & Dimic (Lep., Gracillariidae). Anz. Schädlingskunde,

72: 95-99.

Szaboky, C. 1997. Verbreitung der Roßkastanienminiermotte in Ungarn. Forstschutz-Aktuel, Wien

21: 4.
6 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

An optimized, patented lure for the larger pine shoot beetle, Tomicus piniperda has been developed

and tested in the United States, Poland, and Croatia. Seven different beetle attractants were tested: αpinene, α-pinene oxide, ethanol, nonanal, myrtenal, myrtenol, and trans-verbenol. α-pinene was

tested alone or in combination with two or more of the remaining compounds. Attraction of all

candidate lures was compared to attraction of Tomodor, a Polish commercial lure for T. piniperda,

using the InterceptTM Panel Trap (PT). A lure containing α-pinene, α-pinene oxide, nonanal,

myrtenal, myrtenol, and trans-verbenol was used to compare trap captures in Intercept PT with 12-

unit multi-funnel traps in USA, Theyson trap in Croatia, and IBL-3 trap in Poland. This study

demonstrated that at least a quaternary semiochemical combination, including α-pinene, nonanal,

trans-verbenol, and myrtenol is required to assure maximum trap captures. The best IPM Tech lure

was significantly more attractive than Tomodor when tested in Poland and Croatia. Catches of T.

piniperda in the Intercept PT were significantly higher than in the IBL-3 trap or Theyson trap.

Keywords: larger pine shoot beetle, Tomicus piniperda, attractant, Intercept Panel Trap (PT), insect

monitoring

Introduction

The larger pine shoot beetle, Tomicus piniperda, is native to Europe and Asia. In 1992, T. piniperda

was discovered in the United States (Haack et al. 1997). Czokajlo et al. (1996) demonstrated that the

beetle had been introduced to North America as early as the late 1970s or early 1980s. Since then, T.

piniperda has spread through 12 USA states and two Canadian provinces (NAPIS 2002). The

chemical ecology of T. piniperda is not well understood, and consequently, this pest is difficult to

monitor and manage. Presently in North America, only α-pinene is used as a commercial lure (Phero

Tech, Inc., Delta, BC, Canada). In Europe, Tomodor (Z.D. Chemipan, Poland) and Tomowit (Bio/

Technik/Chemie WITASEK, Austria) are the only known commercially available lures, however none

of these lures attract a satisfactory number of beetles. Several trap designs are used for monitoring

beetle populations. The multi-funnel trap (Phero Tech, Inc., Delta, BC, Canada) has been the most

common trap design used in North America. Several other trap designs have been used in Europe

and Asia, e.g. Theyson trap, drain-pipe trap, barrier traps, and multi-funnel trap. Forest managers

and land owners need an effective T. piniperda monitoring system.

IPM Tech has developed an improved lure for the larger pine shoot beetle based on previous research

(Czokajlo 1998, Czokajlo and Teale 1999, Teale et al. 2001) and unpublished field results. The main

objective of this study was to validate an optimal blend and optimal release rates of semiochemicals,

along with field test trap designs in order to determine the most effective system for trapping T.

piniperda during its reproductive flight in spring.

New Lure for the Larger Pine Shoot Beetle, Tomicus piniperda —

Attractant/Trap Design Combinations Tested in North America and Europe

D. Czokajlo1, B. Hrašovec2, M. Pernek2, J. Hilszczanski3, A. Kolk3, S. Teale4, J. Wickham4 and P. Kirsch1

1

IPM Tech, Inc. 4134 N. Vancouver Ave, Suite 105, Portland, OR 97217, USA

2

University of Zagreb, Zagreb, Croatia

3

Forest Research Institute, Warsaw, Poland

4

State University of New York, College of Environmental Science and Forestry, Syracuse,

 NY 13210, USA
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 7

Materials and Methods

Experiments were conducted in the United States,

Poland, and Croatia in the spring of 2002. In the

United States, the experiment was conducted in an

isolated (5 ha), unmanaged, 50-year-old Scots pine

stand near Syracuse, NY. In Croatia, the experiment

was conducted in a mixed 90% Pinus sylvestris, 10%

P. nigra uneven age (40 to 80-year-old) forest. In

Poland, the experiment was conducted in a 65-yearold, even-aged Scots pine forest near Suprasl.

Beetles were caught in InterceptTM Panel Trap (Int

PT, IPM Tech, Inc., Portland, OR, USA) and in: 12

unit multi-funnel trap in the United States, IBL-3

funnel trap in Poland, and Theyson trap in Croatia

(Fig. 1). Traps were spaced at 15 m or more, with

the collection cup or container about 30 cm above

the ground. The chemicals used were: α-pinene

(Berje, Inc., 98%), α-pinene oxide (Elf-Atochem,

96%), ethanol (Aaper Alcohol and Chemicals, Co.,

100%), nonanal (Polarome, 98%), myrtenal

(Aldrich, 98%), myrtenol (Aldrich 98%), and trans-verbenol (IPM Tech, Inc., 99%). The

compounds were released separately and combined into mesh bags for

different treatments (Fig 2). Lure combinations, release dispensers and rates

of release are provided in Table 1. There were eight treatments in the US

experiment and seven treatments in Poland and Croatia. Each treatment was

replicated ten times. Beetles were collected weekly.

The field data were subjected to a single factor ANOVA. Trap catches from

the United States were log transformed and trap catches from Croatia were

square root transformed to satisfy ANOVA assumptions. The HSD test was

used to compare means in Poland and LSD test was used to compare means

in Croatia and in the United States (Stat Soft, Inc., 1995).

Figure 2.—Tomicus

piniperda IPM Tech’s lure

(left) and Tomodor (right).

Figure 1.—Intercept PT (left), Multi-funnel trap

(center), IBL-3 trap (top right), Theyson trap

(bottom right).

Table 1.—Candidate semiochemicals for Tomicus piniperda.

* Treatment D was used to compare captures in Intercept PT, Theyson trap, and Multi-funnel trap.

Common Name Abbreviation Release device Release rate 

(mg/24h) 

Treatment* 

α-Pinene 

α-Pinene Oxide 

Nonanal 

(-) Myrtenal 

trans-Verbenol 

(-) Myrtenol 

Ethanol 

Tomodor 

α-P 

α-P-ox 

N 

M-al 

t-V 

M-ol 

E 

2 LDPE bulbs 

2 LDPE vials 

2 LDPE vials 

LDPE pouch 

LDPE pouch 

LDPE pouch 

LDPE pouch 

300 

4 

16 

12 

4 

4 

70 

A,B,C,D,E,F 

D,E 

B,C,D,E,F 

C,D,E 

B,C,D,E,F 

B,C,D,E 

E 

Tomodor 
8 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Results

The best IPM Tech lure was significantly more attractive than Tomodor and α-pinene lures when

tested in Poland (Fig. 3) and Croatia (Fig. 4). Data from the United States was inconclusive (Fig. 5).

In Poland, IPM Tech’s best lure attracted 638% more beetles than Tomodor and 176% more beetles

than α-pinene. In Croatia, the best IPM Tech lure attracted 650% more beetles than Tomodor and

233% more beetles than α-pinene. In the United States, captures in traps baited with the best IPM

Tech lure, Tomodor, or α-pinene were not different. However, the data collected in the United States

was probably inconclusive because in 2002, the reproductive flight of T. piniperda occurred unusually

late in the spring and was extended over a period of several weeks; in addition, population levels were

unusually low. Also, in Poland and Croatia, the Tomodor lure attracted significantly fewer beetles

than α-pinene (by 363% and 278%, respectively); however this was not the case in the United States.

Captures of T. piniperda in Intercept PT in Croatia were significantly higher than in the Theyson trap

(by 216%).

Conclusions

The new IPM Tech trap (Intercept PT) and lure for T. piniperda proved to be superior to those used

commercially in Europe. IPM Tech’s lure for T. piniperda performs better than commercially available

European lures and better than the α-pinene lures used in the United States. Our research indicates

that at least a quaternary semiochemical combination, including α-pinene, nonanal, trans-verbenol,

and myrtenol is required to assure maximum trap captures. Further, IPM Tech’s Intercept PT proved

to be the best trap compared to any of the European trap designs tested in this study.

Figure 5.—Trap captures of Tomicus piniperda in INT PT

and Multi-funnel traps baited with various IPM Tech lures

and Tomodor (Polish lure) near Syracuse, NY, USA, 2002.

	
	
	

 


	




 


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Figure 3.—Captures of Tomicus piniperda in Intercept

PT and IBL-3 traps baited with various IPM Tech lure

combinations and Tomodor (Polish lure) Poland, 2002.

Figure 4.—Trap captures of Tomicus piniperda in

INT PT and Theyson traps baited with various IPM

Tech lures and Tomodor (Polish lure) Croatia, 2002.

  



































	




	





	




	




	









	




	

























	





































	







 

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Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 9

References Cited

Czokajlo, D. and S.A. Teale. 1999. Synergistic effect of ethanol to α-pinene in primary attraction

of the larger pine shoot beetle, Tomicus piniperda. J. Chem. Ecol. 25(5): 1121-1130.

Czokajlo, D. 1998. Semiochemicals for the larger pine shoot beetle, Tomicus piniperda L. And its

clerid predators. Ph.D. Dissertation. State University of New York, College of Environmental

Science and Forestry. 164 pp.

Czokajlo, D., R.A. Wink, J.C. Warren, and S.A. Teale. 1997. Growth reduction of Scots pine,

Pinus sylvestris L. caused by the larger pine shoot beetle, Tomicus piniperda (L.)(Col., Scolytidae) in

New York State. Can. J. For. Res. 27, 1394.

Haack, R.A., R.K. Lawrence, D.G. McCullough, and C.S. Sadof. 1997. Tomicus piniperda in

North America: An integrated response to a new exotic scolytid. In Proceedings: Integrating

cultural tactics into the management of bark beetle and reforestation pests, J.C. Grégoire, A.M.

Liebhold, F.M. Stephen, K.R. Day, and S.M. Salom, Eds. (USDA For. Ser. Gen. Tech. Rep. NE236), pp. 62-72.

NAPIS. 2002. Website: www.ceris.purdue.edu/napis/pests/psb Stat Soft, Inc. 1995. Statistica for

windows (Computer program manual). Tulsa, Oklahoma.

Teale, S.A., D. Czokajlo, and F.X. Webster. 2001. Pine shoot beetle attractant composition. U.S.

Patent # US 6,203,786 B1.
10 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

In 1990 and 1999, heavy storms accompanied by the worst gales ever recorded in Switzerland, struck

Europe and left millions of cubic metres of windthrown Norway spruce trees; this provided breeding

material for the eight-toothed spruce bark beetle (Ips typographus L.) and led to mass attacks in

subsequent years which resulted in the additional loss of millions of cubic meters of standing spruce

trees. In addition to the ecological concerns, many forest owners were faced with a difficult financial

situation, resulting in a change in strategy that left some storm and bark beetle damaged areas

uncleared. Also, logistical issues made it sometimes impossible to remove all of the timber before a

new generation of beetles emerged. This situation forced forest services and land-owners to set

priorities. To address questions related to developing a new risk assessment, we initiated observation

projects about scolytid behaviour occurring in variously threatened storm areas and regions.

Keywords: storm damage, bark beetles, Scolytidae, Ips typographus, forest protection

Mass attacks of bark beetles following storm damage

In the last decade, two heavy storms struck Western and Central Europe; they were the worst gales

ever recorded in Switzerland. In 1990 storm “Vivian” caused a loss of 5 million cubic meters of

wood, representing a one-year regular cut in Switzerland. Norway spruce stands (Picea abies (L.)

Karst.) in the central and eastern Alps and Prealps were the most severely damaged. A total of about

four million cubic meters of spruce timber was blown down. In the following six years, the eight

toothed spruce bark beetle (Ips typographus L.) caused mass attacks which resulted in the death of

another 2 million cubic meters of standing spruce trees (Fig. 1). This phenomenon was also a record

for Swiss forests.

In 1999 storm “Lothar” produced 13 million cubic meters of windthrown wood, which included 8

million cubic metres of spruce. The worst storm damage occurred in the western and central Plateau

regions and in the Prealps. In addition to spruce, windthrows occurred also in many mixed and

broadleaf stands. The amount of subsequent bark beetle attacks that will follow this storm is not yet

known, but will certainly exceed the level of timber infested after “Vivian” (Meier et al. 2002).

During a period of 200 years prior to storm “Vivian,” no other Swiss bark beetle gradation produced

more than 500,000 cubic meters of timber loss.

Experiences from mass attacks abroad have demonstrated that spruce bark beetles are one of the most

effective natural factors that can quickly influence forest dynamics by killing large stands of conifers

(Nationalparkverwaltung Bayerischer Wald 1996, Wittwer et al. 1998). Bark beetle gradations follow

frequently after storm damage or when warm and dry periods occur during the growing season

(Weslien and Schröter 1996).

Outbreaks of bark beetles should be contained in order to maintain both forest sustainability and

protection against natural hazards. In Switzerland this is accomplished mainly through mechanical

forest practices especially by preventive clearing of devastated areas and by evacuating or debarking

freshly infested spruces. After the two big storms, the forest services realized that it was impossible to

clear all damaged stands in a timely manner and that there would be a high risk of bark beetle

outbreaks. Reasons and conditions were analyzed that enforce clearing practices in storm-damaged

areas and bark beetle infestation spots, as well as decisions to leave damaged areas uncleared. Priorities

had been established and new strategies in bark beetle management and risk assessment were

developed.

Bark Beetle Management After a Mass Attack — Some Swiss Experiences

B. Forster, F. Meier and R. Gall

Forest Insect and Disease Survey FIDS, Swiss Federal Research Institute WSL CH-8903 Birmensdorf
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 11

Knowledge about Ips typographus

Ips typographus is the best known forest insect in Central Europe. During the last 200 years,

numerous publications have dealt with its biology, epidemiology and management. Ips typographus

has a strong predilection for mass attacks, consequently after storm events, beetle populations build

up rapidly in wind thrown spruce stems and there is a high risk for subsequent attacks in

neighbouring spruce forests. There is a strong relationship between storm intensity and subsequent

bark beetle attacks (Fig. 2 and Fig. 3). In the first vegetation period after a storm, beetle populations

are able to multiply by a factor of more than 10 in only one generation (Wermelinger et al. 1999). In

later years, natural enemies help to control excessive propagation, but under favourable weather

conditions and if there are still plenty of susceptible host trees, mass attacks will often continue for

several years. Emerging bark beetles have dual strategy which allows a portion of the population to

stay in suitable infestation spots and allows other to spread to new areas (Duelli et al. 1997). Flight

distances can vary considerably. Active flight normally takes place within the first 500 metres however

some can get caught by updrafts and then transported over distances of several kilometres. In

mountain areas with steep slopes, passive wind transport of beetles seems to be more frequent because

the area of turbulence that occurs above tree crowns can easily be reached by horizontal flight.

At lower elevations, two generations of Ips typographus can normally be observed per year; above ca

1300 metres asl., only one generation is common. This is one of the reasons why mass attacks peak

normally earlier in the Plateau than in the Alps. In 2000, immediately after the storm “Lothar”,

breeding conditions for I. typographus were very favourable. An abundance of damaged spruce timber

was available as suitable breeding material, and very favourable weather conditions occurred,

resulting in an explosion of beetle populations (Fig. 1). In warmer areas, two and a half or even three

generations of beetles were observed and a second generation was recorded in areas up to about 1600

metres asl.

Figure 1.—Yearly infestation and sanitary felling of Ips typographus attacked spruce in Switzerland

0

200000

400000

600000

800000

1000000

1200000

1400000

1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

remainig infested timber

winter sanitary fellings

summer sanitary fellings

Storm Vivian

Storm Lothar

Infested timber in m3

Ips typographus situation

in Switzerland 1984-2001
12 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Figure 2.—Density of storm damage by forest district, caused by “Vivian” 1990

(dark colours indicate heavy windthrows)

Figure 3.—Density of bark beetle attack by forest district 1992-1996 (dark colours indicate heavy

attacks by Ips typographus)
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 13

Field experiences and new challenges

During the 1990s and after storm “Vivian”, there were only a few storm-damaged areas and

neighbouring spruce stands where bark beetle control activities were not implemented. In these

regions, secondary beetle attack on storm-damaged timber often exceeded 60% on average. In the

worst case, new spot infestations spread until almost the entire stand was killed (Forster 2001b);

similar phenomena have also been described in Germany (Niemeyer et al. 1995). Within some

regions where severe storm damage occurred and where adequate control measures could not be

taken in time, the percentage of secondary timber lost due to beetles approached 100%. Examples of

this are described from the Toggenburg Valley in the canton St. Gall (Schmidtke and Scherrer 1997)

and from the Schwanden region in the canton Glarus (Kantonsforstamt Glarus 1995). Conversely,

good experiences with efforts to remove storm damaged timber occurred in the severely devastated

eastern Bernese Oberland or in the canton Schwyz, where secondary beetle attacks were recorded on

only 20 to 40% of windthrown trees. The removal of damaged trees from storm areas affected by

“Vivian” and reduction of subsequent bark beetle attacks was also observed in the canton Wallis

(Metral 1995). These examples indicate that, even in a disastrous situation, forest protection

measures are effective in lowering subsequent bark beetle damage to about 50% of that which would

have occurred without intervention.

Today, the demands of forest owners and the public are changing considerably and more storm and

bark beetle damaged areas will remain uncleared. In addition to ecological concerns, the difficult

financial situation experienced by many forest owners has caused them to consider changing

strategies and leaving some damaged areas uncleared. Many mountain forest owners are unable to

cover their harvesting costs because of the decline in timber revenue. Logistical reasons (accessibility)

made it sometimes impossible to remove all timber before it was infested and before a new generation

of beetles emerged. These facts forced forest services and timber land owners to establish priorities

(Forster 1998). To address questions related to assessment of risk, the WSL initiated observation

projects of scolytid behavior in different threatened storm areas and regions (Forster 2001a).

As a result of these projects, we propose the following recommendations: an overview of a storm

disaster must be established and the regional forest functions must be known. The necessity for

clearing damaged stands to satisfy a given forest function needs to be assessed. Then the means

(harvest specialists, machinery, time) must be evaluated along with the financial situation and the

feasibility of hiring additional manpower. If the means are not insufficient to clear all areas in time,

or other objections against clearing exist, priorities must be established. Due to the mobility of the

beetles, a common strategy must be considered for entire valleys or landscape compartments

encompassing several square kilometres.

In order to reduce infestation levels in strict protection forests, disaster areas should normally be

cleared. In some cases, the stems can be debarked and then used in place as paravalanche

construction. If such compartments of at least two square kilometres can be cleared to prevent

potential attacks or to destroy infected breeding material in time, this will help to lower the risk of

secondary bark beetle attack on standing trees. In areas with appropriate forest protection measures,

mass attacks peak earlier than in other locations but fewer standing trees will be infested.

If all wind thrown trees cannot be removed or debarked in time, or in less important protection

forests, adapted management strategies should be used. The stated goal is to limit secondary damage

by bark beetles to such a degree that sustainable forest management can be realized. Because not all

windthrown trees on totally damaged areas will be infested before they dry out, we propose to first

clear the areas with a high proportion of thrown trees before clearing areas with mainly broken stems.

Fallen trees that still have some root contact with the soil and/or that are lying in the shade of

standing trees remain suitable for bark beetle colonization for a longer period of time. Therefore, this

will reduce the availability of potential breeding material in subsequent years. Despite new

recommendations about establishing priorities, a mixture of different management strategies are

observed quite often in damaged stands, especially within private forests. This is a result of
14 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

differences among owners, their means (manpower, finances, machinery) and their individual

interpretation of priorities and opportunities. Management conflicts arise along the borders of

different ownerships, especially if stands containing storm damage and bark beetle infestations border

on managed stands where control practices are being implemented. In these cases buffer zones of

some 100 to 1500 metres in width should be established (Niemeyer et al. 1995 and Heurich et al.

2001). However, frequently there is not enough space available for buffer zones and consequently the

edges of managed stands will be re-infested. It is almost impossible to determine to what degree

infestations in unmanaged stands contribute to new infestations that occur in neighbouring stands.

The actual “state of the art” on what is known about bark beetle behaviour and the effectiveness of

control measures was compiled and published a few years after the storm “Vivian” (Jansen and Duelli

1993). Later the Swiss Forest Agency and the WSL compiled a key on windthrow clearing based on

our initial experiences with “Vivian” (BUWAL 2000). Recommendations were again published after

the storm “Lothar” (Forster et al. 2000, Forster 2001c) and communicated further through training

courses and through the internet (www.pbmd.ch).

Conclusions

• There is a strong relationship between the intensity of storms and subsequent bark beetle attacks.

• In cases of disastrous storm damage in Norway spruce stands, subsequent bark beetle outbreaks can

not be avoided and secondary damage on standing trees must be accepted.

• If newly attacked standing trees can be detected and processed efficiently, the gradation will

generally subside sooner than in stands where the level of intervention is inadequate. Our experiences

indicate that even in a disastrous situation, the application of forest protection measures will

effectively lower subsequent bark beetle damage to about 50% of that which would occur without

intervention measures.

• By establishing priorities, the course of the gradation can be influenced regionally. It is very

important that resources should not be spent inefficiently or for punctiform control measures;

resources must be committed to the regions most at risk. The same management strategy must be

used within landscape compartments, throughout the affected region regardless of ownership.

• In Swiss mountain forests, the annual growth of timber has not been harvested for many years. This

practice has provided high stocks of timber which will be more at risk of storm and bark beetle

damage in future years. Additionally, bark beetles are likely to play an even more significant role in

forest dynamics if projections on climate change will lead to warmer vegetation periods.

References Cited

BUWAL (ed.), 2000. Entscheidungshilfe bei Sturmschäden im Wald. Schriftenreihe Vollzug

Umwelt. Bundesamt für Umwelt, Wald Landschaft (BUWAL), Bern. 100 p.

Duelli, P., P. Zaradnik, M. Knizek and B. Kalinova. 1997. Migration in spruce bark beetles (Ips

typographus L.) and the efficiency of pheromone traps. J. Appl. Ent. 121, 297-303.

Forster, B. 1998. Storm damages and bark beetle management: how to set priorities. In:

Methodology of Forest Insect and Disease Survey in Central Europe, Proceedings of the first

Workshop of the IUFRO WP 7.03.10 - Ustron-Jaszowiec, Poland, April 1998. Edited by Grodzki,

W. et al., IBL Forest Research Institute, Warszawa: 161-165.

Forster, B. 2001a. Bark beetle survey: Can monitoring of Ips typographus help to minimise control

measures? In: Knizek, M. et al. (eds.), 2001: Methodology of Forest Insect and Disease Survey in
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 15

Central Europe. Proceedings of the IUFRO WP 7.03.10 Workshop, Sept. 24-28 2000, Busteni,

Romania. Brasov, Forest Research and Management Institute (ICAS), Section of Brasov, 22-25.

Forster, B. 2001b. Chronologie der Borkenkäferentwicklung im Raum Schwanden 1990 bis 1997.

In: Sophie und Karl Binding Stiftung (ed.) 2001: Binding Preis für vorbildliche Waldpflege 2001.

Vivian als Chance. Gemeinde Schwanden GL. Basel, 115 p. 41-42.

Forster, B. 2001c. Käferholz erkennen und richtig handeln. Wald Holz 82, 8: 72-74.

Forster, B., B. Wermelinger and F. Meier. 2000. Sturmschäden und Borkenkäfer. Die Situation

nach ”Lothar”. Wald Holz 81, 2: 40-42.

Heurich, M., A. Reinelt and L. Fahse. 2001. Die Buchdruckermassenvermehrung im Nationalpark

Bayerischer Wald. In: Waldentwicklung im Bergwald nach Windwurf und Borkenkäferbefall.

Bayer. Staatsforstverwaltung Wiss. Reihe, Grafenau, Vol. 14, 9-48.

Jansen, E. and P. Duelli. 1993. Borkenkäfer: Was wissen wir, was vermuten wir, was sollten wir

wissen? Schweiz. Wald 129,7-8:31-33.

Kantonsforstamt Glarus (ed.) 1995. Sturmschäden im Glarner Wald vom 27./28.2.1990.

Schlussbericht. Glarus. 52 p.

Meier, F., R. Engesser, B. Forster and O. Odermatt. 2002. Forstschutz-Überblick 2001.

Birmensdorf, Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft. 18 p.

Metral, R. 1995. Bekämpfung des Borkenkäfers im Unterwallis. Der Aufwand hat sich gelohnt.

Wald Holz 76,6:20-21.

Nationalparkverwaltung Bayerischer Wald (ed.). 1996. Totholz im Nationalpark Bayerischer

Wald, Entwicklung des Anteils abgestorbener Fichten. Grafenau, 36 p.

Niemeyer, H., J. Ackermann and G. Watzek. 1995. Eine ungestörte Massenvermehrung des

Buchdruckers (Ips typographus) im Hochharz. Forst Holz 50,8:239-243.

Schmidtke, H. and H.-U. Scherrer. 1997. Sturmschäden im Wald. Schlussbericht NFP 31. Zürich,

vdf Hochschulverlag. 38 p.

Wermelinger, B., M.K. Obrist, P. Duelli and B. Forster. 1999. Development of the bark beetle

(Scolytidae) fauna in windthrow areas in Switzerland. Mitt. Schweiz. Entomol. Ges. 72, 3-4: 209-

220.

Weslien, J. and H. Schröter. 1996. Natürliche Dynamik des Borkenkäferbefalls nach Windwurf.

Allg. Forst Z./Der Wald 51,19:1052-1055.

Wittwer, D., K. Matthews, K. Zogas, L. Trummer, E. Holsten, B. Schulz, P. Hennon, M.

Schultz, J. Riggs and R. Burnside. 1998. Forest Insect and Disease Conditions in Alsaka – 1998.

Gen. Tech. Rep. USDA For. Serv. R10-TP-74. 57 p.
16 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

This paper presents the design of a regulation model of the little spruce sawfly that is based on

monitoring of defoliation. This method is based on the assessment of the percentage of defoliation of

each whorl from ca. 100+ trees, beginning from the top and using four classes of defoliation. The

critical value influencing the height of current increment of trees is six. Consequently 20 yellow

sticky boards installed in lines on every other tree could monitor the next spring abundance of sawfly

adults. Critical value is about 11 to 19 females per one sticky board (format A5). Impact of low

temperature on sawfly populations during swarming is still not clear. Possibilities for using chemical

measures for control are discussed.

Several outbreaks of the little spruce sawfly (Pristiphora abietina (Christ 1791)), covering thousands

of hectares of spruce forests, have occurred in Europe (Pschorn-Walcher 1982). Little spruce sawfly is

the most numerous tenthredinid in both young and older spruce stands from an altitude of 250 to

700 m a.s.l. in the eastern part of the Czech Republic (Holusa 1999, 2002). Every year spraying of a

portion of this region is necessary (e.g. Pschorn-Walcher 1982, Liska 1999, 2000, Liska et al. 1991),

because an integrated pest management (IPM) approach to address this problem is lacking.

In spite of this, the pest status of little spruce sawfly is not clear (Regulation no. 101/1996 Sb. dated

March 28th 1996 of Ministry of Agriculture, Czech Republic), because larvae feed only on current

year needles and therefore do not cause total defoliation of trees (Pschorn-Walcher 1982). Therefore

it suggests that some level of economic threshold should be established, however, we lack appropriate

methods to monitor this pest. Pristiphora abietina is usually monitored by estimating the density of

cocoons in the soil (Bogenschütz 1986, Pschorn-Walcher 1982); however this procedure is time

consuming, is not practical on a large scale, and is very unreliable (Janásek 1964). Thus, a new

method of evaluation is needed. (Bogenschütz 1986). An assessment of defoliation (i.e. larval

feeding) provides an indirect, objective method to determine the intensity of tenthredinid infestations

(see Svestka and Holusa 2000, Holusa and Holusa 2002, Holusa and Drápela in press.). In order to

work out an approach to develop an IPM system for P. abietina, the following questions needed to be

answered:

1. What degree of defoliation causes a decrease of height tree increment?

Pristiphora abietina population fluctuations are of the temporary-distractive type, thus causing

outbreaks that may last from a few years to several decades (Pschorn-Walcher 1982). Outbreaks of

the little spruce sawfly can be only eruptive, because cocoons lying 10 months in the litter can be

attacked by predators (in Neodiprion sertifer discussed by Larsson et al. 1993) and larvae that drop to

the ground to pupate can be attacked by fungi. There is also a possibility that cocoons can overwinter

in the soil for more than one year (Pschorn-Walcher 1982), however the first author found that this

occurs in less than 1% of overwintering cocoons in the eastern part of the Czech Republic (Holusa

1999).

2. What is the best method to assess the abundance of sawfly adults in the following spring?

Integrated Management of Little Spruce Sawfly (Pristiphora abietina):

Design Pattern

J. Holusa1 and K. Drápela2

1

Forestry and Game Management Research Institute Jíloviste-Strnady, Office Frýdek-Místek,

 Nádrazní 2111, CZ-73801 Frýdek-Místek

2

Mendel University of Agriculture and Forestry, Zemedelská 3, CZ-61300 Brno
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 17

1. Impact of defoliation on the height of current increment of trees

Introduction

Nageli (1936) found that P. abietina caused a loss of 33-40% height tree increment in 1917-1934 in

Switzerland. In Mooswald at Freiburg i.B., loss of height tree increment reached an average above 2

m (Niechziol 1958 in Pschorn-Walcher, H. 1982). In the case of very heavy defoliation, height tree

increment declines rapidly and after several years of repeated defoliation, it decreased to zero; the loss

is greater in younger forests. In spite of these observations no data exists that defines the relationship

between the density of populations and increment loss.

In the past, a method of assessing defoliation caused by Tenthredinids (without discrimination of

species) was prescribed but lacked precision (CSN 482718: Ochrana lesa proti pilatkám na smrku.

1958). The loss of needles was classified into four groups (loss of 1/3 of needles, 1/3 - 2/3, more than

2/3, and total defoliation). We have developed a scale of damage on spruce (Svestka and Holusa

2000, Holusa and Holusa 2002, Holusa and Drápela in press) which allows us to provide an

objective evaluation of insect defoliation. This method was used to establish the degree of defoliation

that can cause the decrease of tree height increment.

Method

About 100 trees in each plot were investigated to assess the percentage of defoliation of each whorl

beginning from the top of the tree using four classes of defoliation:

Rare (value 0,1) - very light defoliation of annual shoots – below 10% of shoots were eaten;

light defoliation (value 1) - 10-50% of annual shoots were eaten;

heavy defoliation (value 2) - 50–90% of annual shoots were eaten

total defoliation of annual shoots (value 3) –over 90%.

A damaged tree leader (terminal) is evaluated by 1 (no feeding by 0). The average defoliation of each

whorl was calculated per tree and then the results of all whorls were accumulated (this value is named

as the degree of defoliation in this work).

We have determined the mean height current increment of young forests. We have measured height

current increment of young forests 4-5 m (i.e. 6-12 years old) using a special measuring pole with 1

dm scale. In all places a set of 100 trees was investigated. Forests were separated according to

condition of growth. Three types of potential habitats (Querceto-Fagetum, Fagetum, Abieto-Fagetum)

were examined. Statistical analyses including correlation and regression analyses of the influence of

defoliation on height current tree increment were

performed using Statistica 6.0 (a = 0.05).

Results

Defoliation data sets are non-normal, because they

are positively skewed and leptokurtic or platykurtic.

Because Box-Cox transformation on normality was

often not successful, the median value of defoliation

distribution is used. The method is easy and fast; on

average it is possible to evaluate 100 trees in less

than half an hour, which is an important

consideration for forestry applications.

The forests of the habitat Querceto-Fagetum were

very weakly defoliated, therefore no correlation was

found between the degree of defoliation and mean

of height current increment. In the other two

habitats, positive correlations were found however it was necessary to confirm the relation due to

other statistical calculation (Figures 1, 2). The parabola was used to characterize the relationship

Figure 1.—Correlation between the degree of defoliation

and current height tree increment (habitat Fagetum)

y = -0.0294x2 + 0.0582x + 5.8131

R2

 = 0.4829

0

1

2

3

4

5

6

7

8

0 2 4 6 810

Degree of defoliation

Height current increment
18 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

because it corresponds better to the consideration that

only more intensive defoliation should negatively

influenced the tree height current increment.

No correlation was found between the degree of

defoliation and the height tree current increment in the

next year.

Based on this result, we can conclude that a degree of

defoliation equal to six can negatively influence tree

height current increment. There is an exception as e.g.

the point in Fig. 2, which is probably caused by drought

or fungus (or an unknown factor).

Discussion

The impact of defoliation on the height current

increment of trees is the most important factor in assessing the economic injury level though we need

to determine also the impacts of treatment on non-wood-producing values of the forest, ecosystems,

selection, and on the population dynamics of the pest (contraction of amplitude). The impact of

control measures on the ecosystem could be reduced by using insecticides based on ecdysoids (growth

regulators), whose impact on ecosystem health is minimal.

In the case of other stresses (mainly fungi in the habitat Querceto-Fagetum), the critical degree of

defoliation should be decreased. Forest health condition will be a much more important factor than

the decrease in height tree increment.

The defoliation of an entire young spruce stand (up to 40 years old) may be evaluated using a

modified method. For the entire stand, a scale with four levels was deployed using a critical mean

defoliation value of approximately 50% of trees (see Fig. 3). The degree six of critical defoliation

corresponds approximately with the total defoliation of

forests if three or more of the top whorls are consumed

on over one half of the trees. Defoliation can be

displayed graphically on a grid map (Central European

System) in which the map fields are delimited by

parallels of latitude (6 by 6 minutes) and meridians (10

by 10 minutes) with an approximate size of 11.2 x 12.0

km in Central Europe. Circles of different size in the

map field can be used to designate the degree of

defoliation for an entire forest. The range and intensity

of infestation and the change in defoliation from year to

year are easily observed (Holusa and Holusa 2002).

Using the present method and maps in conjunction with

GIS, and including information on altitude, total annual

precipitation, average annual temperature, moisture, and

characteristics of the habitat, pest risk assessment maps

can be established.

2. Monitoring adult sawfly abundance

Introduction

Sawfly adults are generally attracted to yellow traps

(Murhead-Thompson 1991). For monitoring of spruce

web-spinning sawflies (Cephalcia spp.), some authors

Figure 3.—The infestation caused by tenthredinids

to young spruce forests in the eastern part of the

Czech Republic in 2000 (marks: point - throughout

the stand, only a single shoot on trees is consumed;

small circle - half of trees with one or two top whorls

consumed; mid-size circle - more than half of the

trees with three and more top whorls consumed

[this infestation reduces the growth of trees in the

following year], circle of one quarter the size of the

map field - stunted trees; fat line - margin of studied

area) (Holusa and Holusa 2002)

Figure 2.—Correlation between the degree of

defoliation and current height tree increment

(habitat Abieto-Fagetum)

y = -0,0208x2 - 0,0228x + 5,701

R2 = 0,2757

0

1

2

3

4

5

6

7

8

02468

Degree of Defoliation

Height current increment
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 19

used yellow sticky boards (Jensen 1988, Cescatti and

Battisti 1992) and correlated trap captures with the

density of prepupae in the soil (Battisti and Rodeghiero

1998). Berger (1992) found that Pristiphora abietina

adults could also be attracted to yellow traps. The number

of adults captured in traps correlated with the density of

cocoons in the soil.

In recent years, we have acquired positive results and

experience in studies using yellow sticky boards. A

statistically significant relationship was found between

captures in Malaise traps and those on yellow sticky

boards, and a highly significant relationship was found

between the number of captured adults (on five sticky

boards) and the degree of defoliation in seven localities.

To estimate the abundance of adults, it is sufficient to

install yellow sticky boards before swarming and then

check them after swarming is completed. We did not

observe statistically significant difference between samples

taken at different intervals (Holusa and Drápela in press).

The relationships between catch number and defoliation has yet to be confirmed, however there is

another important question that needed to be answered.

3. What number of traps is necessary to ascertain a statistically significant abundance of

sawflies?

Method

The traps consisted of yellow plastic boards 14.8 x 21 cm, coated on both sides with entomological glue,

that were suspended from the top of trees or from a branch at about 2 m above the ground. They were

exposed in lines of 20 boards on the southeastern side of every other tree. All traps were installed in

mid April (prior to adult emergence) and kept in place until mid-June (after the end of swarming).

The number of localities studied in 2001 and 2002 were 30 and 20 respectively. The localities

consisted of young spruce forests in Silesia and eastern Bohemia at an altitude 300 to 500 m a.s.l.

Captured sawfly adults were preserved in 70% alcohol (leg. J. Holusa, coll. VÚLHM JílovisteStrnady). Because of the inequality of variance and non-normality (tested using D ́Agostino

normality test) of the sets in the majority of cases, the Box-Cox transformation on normality was

used to represent the mean capture. Correlation and regression analyses were performed with

Statistica 6.0 (a = 0.05). The sample size necessary to achieve the desired level of precision in

estimating a population mean is given by the following formula (Zar 1984):



 



 





  

 α − β − ν =

s

2

 is the sample variance with n degrees of freedom;

d is the half-width of the desired confidence interval (this accuracy is subjectively chosen

until we have used approximately one third of catch mean);

1- α is the confidence level for the confidence interval;

1- β is the assurance that the confidence interval will not be greater than specified;

t- is the two tailed critical value of t-distribution with (n-1) degrees of freedom;

F is the one tailed critical value of F-distribution with (n-1) and n degrees of freedom.

The degree of defoliation was estimated using the same procedures that were deployed in the previous

study.

Figure 4.—The infestation caused by

Tenthredinids to young spruce forests in

the eastern part of the Czech Republic in

2001(dashed line - area of measures)

(Holusa and Holusa 2002)
20 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Results

We found a highly positive correlation between catch mean of females and subsequent defoliation

(Fig. 5) in nine localities in 2002 (The majority of localities were treated chemically therefore they

could not be used in the regression). No correlation was found when male sawflies were used.

Based on data on the distribution of females on sticky boards, we have established that from 20 to 40

yellow sticky boards are needed to obtain an accuracy equivalent to one third of the mean. If less

efficiency is acceptable, about 20 boards are needed. (Tables 1, 2). In 2001, in the majority of

localities, the numbers of females captured were too low for analysis.

Discussion

A positive correlation was found only between the mean catch of females and subsequent defoliation

possibly because the distribution of females in forests is more equal, resulting in data sets that are

much more homogeneous. This is related to the bionomics and behavior of this species. Female

sawflies actively search along the twigs looking for suitable places to oviposit; on the other hand, male

sawflies are much more active and vagile and fly around the tops of trees mainly on sunny sites.

Therefore the distribution of males is more aggregated. If the defoliation degree of six is critical,

about 11 to 19 females would correspond to this value.

Based on the experiments in 2001 and 2002, the number of boards sufficient to obtain an accuracy

equivalent to one third of the catch mean varies between 20 and 30. The number varies between 20

and 30 because it depends strongly on the sample variance, which differs from place to place. The use

of this number is practical because the time required for the installation of 20 boards is about 30

minutes. Counting the number of captured sawflies depends, of course, on the total number of adults

captured and is sometimes time consuming.

Figure 5.—Relationship between the number of captured Pristiphora abietina

females and the subsequent defoliation of forest stands (y=-1.2604+0.49x; —

confidence interval of model)

Mean catch

Degree of damage
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 21

Table 2.—Number of yellow sticky boards for monitoring of sawfly abundance in 2002.

(A...accuracy, NB...number of boards)

Longitude; Female catch Transformed female Accuracy NB A NB

Latitude mean ± SD catch mean ± SD - ca 1/3 of mean

Kabátice hill 18°16'; 49°39' 3.11±2.7 1.0 21

Paskovský les wood 18°17'; 49°43' 4.13±4.36 2.83±3.69 1.5 35 2.0 21

Slavíè Mt. 18°35'; 49°34' 3.15±3.53 1.95±2.90 1.2 36 1.7 19

Rovná wood Nr. 1 18°41'; 49°38' 13.16±10.65 10.14±8.34 4.0 30 5.0 20

Rovná wood Nr. 2 18°41'; 49°38' 8.20±5.48 3.0 16

The village of Pustá Polom Nr. 1 17°58'; 49°51' 12.38±11.80 8.78±8.41 4.0 36 6.0 18

The village of Pustá Polom Nr. 2 18°00'; 49°51' 18.76±15.00 14.61±13.15 6.0 27 8.0 16

The village of Pustá Polom Nr. 3 18°00'; 49°51' 7.14±7.67 5.26±5.86 2.5 37 .5 21

Kubalánky place 18°19'; 49°36' 8.78±9.38 5.51±8.12 3.0 41 4.3 21

Na horách hill 16°09'°; 50°23' 4.15±2.85 1.4 19

The village of Pøibyslav 16°10'°; 50°22' 25.91±15.76 22.48±13.34 8.0 18

The village of Brná 16°20'; 50°05' 10.10±8.40 7.63±5.44 3.3 28 4.0 20

The village og Nýdek Nr. 1 18°44'°; 49°39' 17.30±11.24 6.0 16

The village og Nýdek Nr. 2 18°44'°; 49°40' 1.15±2.43 failed 0.4 145 1.2 19

The village of Nýdek Nr. 3 18°44'°; 49°40' 13.35±11.33 11.33±7.33 4.0 21

Locality Longitude; Female catch Transformed female catch A NB A NB A NB

Latitude mean ± SD mean ± SD

Metylovická hùrka hill 18°21'; 49°37' 4.30±3.05 2 12 1 39

Paskovský les wood 18°17'; 49°43' 51.20±21.20 35 6 25 9 15 20

Slavíè Mt. Nr. 1 18°35'; 49°34' 6.31±9.74 4 13 3 21

Slavíè Mt. Nr.2 18°35'; 49°34' 29.00±41.61 15 15 20 29

Rovná wood 18°41'; 49°38' 64.00±45.57 30 12 20 23 15 38

The village of Pustá 17°58'; 49°51' 21.73±13.55 19.40±12.67 10 10 7 17 5 30

Polom Nr. 1

The village of Pustá 18°00'; 49°51' 11.85±21.79 0.60±2.81 10 21 7 40

Polom Nr. 2

Kubalánky place 18°19'; 49°36' 16.11±30.98 0.43±2.27 15 19 12 29 8 60

Stoláøka Mt. 18°19'; 49°36' 3.38±5.15 0.12±0.63 3 14 2.5 20 2 29

Table 1.—Number of yellow sticky boards sufficient for monitoring sawfly abundance in 2001.

(A...accuracy, NB...number of boards)

Conclusion

According to these results, we suggest the following model of regulation. Two main criteria are the

degree of defoliation and the abundance of adults in the following spring.

Model of regulation

S (step) 1 Monitoring of forest defoliation

Criterion: If the degree of defoliation exceeds the value 5, go to S2 otherwise continue

monitoring of defoliation.

S2 Monitoring of swarming adults next spring

Criterion: if an average of 15 females or more are caught on yellow sticky boards, go to S3

otherwise continue monitoring of defoliation.
22 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

S3 Coincidence of sawfly swarming with spruce budbreak

Cool and rainy weather can directly influence the swarming of adults, or fecundity of females

could be decreased by low temperature as reported by Gruppe (1998) for Cephalcia abietis

(Linnaeus 1758). Both cases resulted in a weaker attack of shoots by larvae. We do not know

any exact criterion and the decision is based only on field observations. In the case of high

abundance of eggs on shoots, go to S4.

S4 Chemical (biological) measures

There is no effective biological control for P. abietina so that only chemical treatments are

available. However, there is a possibility of using fungal spores against mature larvae before they

fall into the litter (Führer et al. 2001). To eliminate negative impacts on the ecosystem, the

following recommendations should be considered:

1. We should prefer using ecdysoid-based insecticides; synthetic pyrethroids should be

considered for use only against strong insect infestations. On the foothill of the

Moravskoslezske Beskydy Mountains (Czech Republic), three insecticides (Dimilin 48 SC,

Mimic 240 LV, Trebon 10 F) were sprayed on 25 ha plots using ULV aerial application. Results

from this experiment suggest that ULV aerial applications of both Trebon 10 F and Dimilin 48

SC are effective in protecting stands against sawfly larval feeding (Svestka and Holusa 2000).

2. Chemical treatments should be applied in mid-May when P. abietina larvae are in the first to

second instars. However, it is very difficult to determine the timing of application. During the

period 1997-1999 the forests in the hills (altitudes around 300 m a.s.l.) were sprayed from May

19 to 22 (i .e. the period when the larvae of 1st and 2nd instars are most numerous), stands in the

highlands (500 m a.s.l.) about one day later, and stands at an altitude of 700 m a.s.l. until May

26 (Holusa and Svestka 2000) (Fig. 4).

3. Criteria for selecting forests for treatment are as follows:

– Spruce stands should be younger than 40 years, when the impact on height tree increment is

most severe. Only very heavily damaged older forest stands should be considered for spraying.

– Prevalence of spruce must be more than 70%, otherwise the percentage of spruce could be

eliminated by tending and other planting measures.

– Aerial application should be used to spray only those spruce stands that are larger than 1 ha.

However smaller areas must be treated from the ground to prevent the increase and spread of

populations to adjacent areas.

In forests situated in broken highlands, it is necessary to use helicopters that can maneuver

better under flight speeds of 80 km/hour and therefore provide more precise applications.

Further studies are needed to confirm parameters in the proposed regulation model:

– Confirm the degree of defoliation that influences height current increments of trees.

– Assess the impact of fungal infestation on the incidence of defoliation.

– Confirm the relationship between the number of captured females and defoliation.

– Determine the coincidence of sawfly swarming and budbreak of spruce.

– Determine the impact of low temperatures on female fecundity.

– Establish an economic threshold level (which will be based on a comparison of increment

loss and costs of control measures.

– Evaluate the use of fungi for biological control.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 23

References Cited

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Berger, R. 1992. Gelbtafeln: eine Methode zur Kontrolle von Fichtenblattwespen. Mitt. Dtsch.

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Cescatti, A. and Battisti, A. 1992. Distribution and ecology of Lymantria monacha and Cephalcia

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Führer E., Rosner A., Schmied A. and Wegensteiner R. 2001. Studies on the significance of

pathogenic fungi in the population dynamics of the Lesser Spruce Sawfly, Pristiphora abietina

Christ. (Hym., Tenthredinidae). J. Appl. Ent. 125: 235-242.

Gruppe, A. 1998. Influence of genotype and temperature on the fitness of the webspinning sawfly

Cephalcia abietis (Hymenoptera: Symphyta, Pamphilidae), pp. 439-440. In: Brunnhofer V. &

Soldán T. (eds.): Book of abstracts, VIth Eur. Congr. Ent. Ceské Budejovice, August 23-29, 1998,

760 pp.

Holusa, J. 1999. Bionomie pilatky smrkové (Hymenoptera:Tenthredinidae) na severní Morave a ve

Slezsku v letech 1998-1999. Zprávy lesnického výzkumu 44: 19-27.

Holusa, J. 2002. Species composition of spruce tenthredinids (Hymenoptera: Tenthredinidae) in the

eastern part of the Czech Republic. Biologia, Bratislava 57: 213-222.

Holusa, J. and Drápela, K. In press. Yellow sticky boards: a possible way of monitoring the little

spruce sawfly (Pristiphora abietina) (Hymenoptera: Tenthredinidae). J. Appl. Ent.

Holusa, J. and Holusa, O. 2002. Monitoring of sawfly (Hymenoptera: Tenthredinidae) infestation on

spruce. J. For. Sci. 48: 219-224.

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Jensen, T. S. 1988. Phenology and spatial distribution of Cephalcia (Hym., Pamphilidae) imagines

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Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 25

Abstract

The spread of bark beetle outbreaks in the Tatra Mountains was explored by using both terrestrial

and remote sensing techniques. Both approaches have proven to be useful for studying spatial

patterns of bark beetle population dynamics. The terrestrial methods were applied on existing forestry

databases. Vegetation change analysis (image differentiation), digital elevation model, and stand

characteristics have been integrated in the remote sensing part of the study. Results have revealed that

the spatial pattern of bark beetle spread depends on the phase of the outbreak and on the insolation

(amount of incoming solar radiation) of stands on mountain slopes and, specifically on the bark

beetle spots themselves.

Introduction

The Tatra Mountains are located in the Western Carpathians on the border between Slovakia and

Poland. The entire area of the Tatra Mountains has been designated as a protected area – comprising

two National Parks: Tatrzański Park Narodowy (TPN) in Poland and Tatranský Národný Park

(TANAP) in Slovakia.

In 1995-97, a serious outbreak of the spruce bark beetle Ips typographus (L.) (Col.: Scolytidae)

occurred in the Norway spruce stands of the Tatra Mountains, on both the Polish and Slovak sides of

the border (Fig. 1). This insect, recognized as the most serious pest associated with Norway spruce

stands, caused dramatic tree mortality in the region of Łysa Polana – Morskie Oko – Tatranská

Javorina. On the Polish side, in stands which are under a strict protection regime, mature Norway

spruce stands died over large areas; on the Slovak side, where several different forest protection

strategies were applied, many entire stands of Norway spruce had to be felled.

Materials and Methods

We used both terrestrial and remote sensing techniques to conduct spatial analyses of the spread of I.

typographus outbreaks.

Terrestrial Approach

We initiated our research by creating rich databases which contained detailed information about the

characteristics of stands and bark beetle populations. Information on site characteristics, stand

composition and age, and annual tree mortality during the period 1990-1999 was acquired from the

administrative offices of the Tatrzński Park Narodowy (TPN – Poland) and Tatranský Národný Park

(TANAP – Slovakia). The smallest units of data that were used in our research consisted of forest

sub-compartments. The data concerning tree mortality was transformed into tree mortality indices

(TMI) and expressed as the mean volume of infested trees per one hectare in the sub-compartment

(m3

/ha). The data were ranked according to a somewhat adjusted scale developed by Capecki (1981),

with the following ranges of mortality in m3

/ha: 0.01-0.4 – normal, 0.41-1.2 – premonitory, 1.21-

2.4 – intensive, 2.41-10.0 – very intensive, >10.0 – catastrophic.

The digital map with a DTM, covering the research area (Koreň et al. 2002), and the layers

concerning tree mortality, were constructed using a vector oriented software ArcView 3.1. The layers

on tree mortality (TMI) in successive years were used to produce a visualization of spread of bark

Definition of Spatial Patterns of Bark Beetle Ips typographus (L.)

Outbreak Spreading in Tatra Mountains (Central Europe), Using GIS

Rastislav Jakuš 1, Wojciech Grodzki2, Marek Ježík1, Marcin Jachym2

1

Institute of Forest Ecology, Slovak Academy of Sciences, Zvolen, Slovakia

2

Forest Research Institute, Kraków, Poland
26 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

beetle outbreaks. The total area of attacked stands, i.e. the area of all sub-compartments with

recorded trees attacked by bark beetles in a year, were derived from the database.

Remote Sensing Approach

The time series of LANDSAT images for years 1991, 1993, 1995, 1997, 1999, a digital elevation

model, and other GIS data obtained from Koreň et al. (2002), were processed by using by a raster

oriented GIS program IDRISI 32.

Identification of Bark Beetle Spots

Based on the summarized data, we prepared a mask of spruce forest cover on the geographical area

under study. This mask was used for localization of work to spruce stands. First we tried to identify

bark beetle spots on the time series of LANDSAT images with the aid of standard classification

methods, however this approach was not successful. Later we used the vegetation change analysis and

the method of image differentiation (Eastman et al. 2000). This research was applied during the

periods: 1991 - 1993, 1993 - 1995, 1995 - 1997, 1997 - 1999.

The work was intricate, which was caused by the presence of shadows cast within the mountain

environment. We tried to resolve this problem by applying an approach which integrated remote

sensing and GIS tools. A pilot study comparing areas with cast shadows and areas containing bark

beetle spots showed that there was no overlay between these two categories. I. typographus did not

attack forests that occurred on steep North - oriented slopes (Fig. 3) with cast shadows. This

determination allowed us to exclude the areas with cast shadows from our interest in bark beetle spot

identification.

 The selection of suitable vegetation indices was obtained through our conduct of a special literature

review. We selected the following indices: Normalized Difference Vegetation Index, Specific Leaf Area

Vegetation Index, Vegetation Condition Index , Greenness Condition Index, and Normalized Ratio

Vegetation Index. The change analyses were performed using the maps of all the above vegetation

indices. The resultant maps were compared with several forest compartment maps and with the data

obtained on bark beetle damage (Fig. 2). Only the Vegetation Condition Index (TM7 / TM4;

Jakubauskas, Price 1997) was found to be a usable characteristic. The resultant maps were then

compared with aerial infrared photographs of the study area taken by the Research Station of the

Tatra National Park in 1999.

Figure 1.—Intensity of bark beetle

outbreaks in the Tatra Mountains

expressed through mean tree mortality

(m3

/ha) caused by bark beetle attacks

in 1991-2000 in Polish (TPN) and

Slovak (TANAP) parts of the study

area.

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

TPN

TANAP

m3/ha

Year

Tree mortality (m3/ha)
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 27

Figure. 2 a-c.—Spatial development of the bark beetle outbreak

in the Tatra Mountains in 1991 (a), 1995 (b) and 1999 (c), with

the degree of tree mortality (m3

/ha) in the individual forest

sub-compartments.

Spatial analyses

We used spatial analyses to investigate the

processes of spot initiation and spot

spreading. Our analyses of vegetation change

allowed us to distinguish three phases in the

development of bark beetle outbreaks

(progradation: 1991 - 1993, 1993 - 1995;

culmination: 1995 - 1997; retrogradation

1997 - 1999.)

a) Spot initiation: By examining images

indicating areas of bark beetle damage, we

were able to differentiate between new

(initiated in the current year) and old

(initiated in any of the previous years) spots,

and to calculate the areas of both. We then

measured the shortest distances between the

new and old spots. The data obtained were

transferred into the statistical software

STATISTICA for further analyses.

b) Spot spreading: Direction and speed of

spreading were calculated for increasing bark

beetle spots. The calculations were

performed with the use of surface functions

(IDRISI) and trigonometry for every pixel of

the areas examined. Speed of spreading was

measured only on the active (increasing)

spots; spots with no expansion were

excluded from consideration. Further

analyses were performed using raster data at

the pixel level, meaning we measured

parameters for pixels belonging only to

particular spots (one spot could be covered

by several pixels). Then the data were

subjected to the statistical analyses using

STATISTICA software.

Results

Terrestrial research

The well-designed and developed database

was used for assessing the course of I.

typographus outbreaks over time on both

sides of the state boundary (Table 1). The

level of tree mortality remained relatively

constant during the entire outbreak period

(Spearman’s rank correlation rs=0.91***);

however, both the degree of mortality and

the area of stands attacked changed more

dramatically on the Slovak portion of the

area studied, especially during the period

1995-1996 when intensive sanitary cuttings

were deployed.

2c. 1999

2b. 1995

2a. 1991

 0.01-0.4

 0.41-1.2

1.21-2.4

 2.41-10.0

>10.0 
28 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

The outbreak began on several sites that were separated geographically and distributed throughout

the entire study area (Fig. 2a); during the culmination phase, most of the stands in the entire study

area were attacked (Fig. 2b), whereas during the retrogradation phase, attacks receded to certain

stands close to the state boundary and to the initial outbreak

area (Fig. 2c). The distribution of the most seriously

attacked stands based on their exposition is shown in Figure

3. Data on the localization of I. typographus spots provided

by TPN services and based on terrestrial estimations, and

data on the distribution of attacked sub-compartments, had

been overlaid on the map with vegetation types. However,

the classification of vegetation types currently used in

Poland was very simplified as compared to the much more

elaborate differentiation of forest vegetation types used in

Slovakia. Consequently, use of this classification was

possible only in Poland. In the Polish stands attacked by I.

typographus and belonging to only two forest types

(Abietetum and Piceetum tatricum) occurring in two

altitudinal zones (upper and lower mountain zone), we

observed no distinct differences in attack intensity related to

vegetation type/altitudinal zone.

Remote sensing approach

The map of damage caused by the spread of bark beetle

populations is provided in Fig. 4. The comparison between

this map and infrared aerial photographs demonstrated that

99% of bark beetle spots visible on the aerial photos had also been identified by vegetation change

analysis of the LANDSAT time series. Therefore, the map was used in further analyses.

a) Spot initiation: Spatial analyses have shown that the area of new spots was larger than the area of

old spots during the progradation phase (Fig. 5). Incidence of tree mortality was linked mainly with

spot initialization. During the culmination and retrogradation phases, the area of new spots was

considerably smaller than the area of old spots. In this case, the mortality was caused primarily by the

expansion of old spots. The distances between new and old spots decreased during the course of the

outbreak (Fig. 6).

b) Spot spreading: The spots were spread in all directions except south (Fig. 7). The speed of active

spot spreading increased during the outbreaks (Fig. 8).

Table 1.—Area (ha) of stands attacked by bark beetles, derived from the database

year TPN TANAP

1991 387.92 297.22

1992 544.58 224.30

1993 567.55 364.91

1994 672.80 897.34

1995 712.24 1435.29

1996 816.64 1453.52

1997 727.77 1216.60

1998 768.60 92.02

1999 741.53 306.40

0

5

10

15

20

25

30

35

40

45

N

NE

E

SE

S

SW

W

NW

TANAP

TPN

Figure 3.—Distribution of the volume of

infested trees (% of total) on mountain slopes

in the Slovak (TANAP) and Polish (TPN)

parts of the study area.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 29

Figure 5.—Area of new and old bark beetle spots in different phases of bark beetle

outbreaks

Figure 6.—Minimum distances between new and old spots.

0

20

40

60

80

100

120

140

I (91-93) Prog. II (94-95) Prog. III (95-97) Culm. IV(97-99) Retrogr.

Period

Area (ha)

old new

Figure 4.—Map of the spread of bark beetle outbreaks based

on satellite image analysis

Non-Outlier Max

Non-Outlier Min

75%

25%

Median

Median=183.586-32.918*x+eps

0

100

200

300

400

500

II (93-95) Prograd.

III (95-97) Culmin.

IV (97-99) Retrog.

Distance (m)

PERIOD
30 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Discussion

Methodology

Both approaches utilized (terrestrial & remote sensing) have demonstrated their usefulness for

studying the spatial dynamics of bark beetle populations. The terrestrial approach can be applied using

data acquired through common forestry practices used in both Poland and Slovakia and therefore is

relatively inexpensive. Digital maps of forest stands will be made available to foresters in the near future.

The main disadvantage of this approach is its low spatial resolution (compartment). The remote sensing

approach requires the use of spatial methods for processing satellite images and the availability of digital

elevation models and thematic maps. All these technologies are quite expensive, however the remote

sensing approach provides a much higher spatial resolution (30 m for LANDSAT images).

A fairly high accuracy in identifying bark beetle spots (about 99%) was achieved by combining

information obtained from both LANDSAT images and from the thematic databases. Zemek at al.

(1999) achieved 89% accuracy in classifying an area affected by a bark beetle outbreak in the NP

Šumava, using classical remote sensing data. We have achieved relatively good results with our

method, however it places a higher demand on the quality and quantity of thematic information and

time series of LANDSAT images.

The Expansion of Bark Beetle Outbreaks

The general pattern in which I. typographus outbreaks spread agrees with descriptions of other authors

(Schwerdtfeger 1955, Stolina 1970, Capecki 1978). The distribution of most frequently attacked

stands based on their exposure reflects the general distribution of slopes in both parts of the studied

area. Nevertheless, attacked stands are distributed more southward and eastward, which agrees with

observations of I. typographus outbreaks from other mountain areas (Grodzki 1997). Our results have

shown that during progradation phase of the outbreak, the spread arises mainly from new bark beetle

spots. In the culmination and retrogradation phases, outbreaks spread by further expansion from old

spots. Lohberger (1993) revealed that 69% of the spots studied during the period 1988 - 1991 in the

NP Bayerischer Wald were spread from old spots while only 6% of spots were attacked only in the

first year. Thus, the dominance of continuous growth of spots could be characteristic of I. typographus

outbreaks and could explain the dominance of old spots that we observed in later outbreak stages in

the Tatra Mountains.

We have recorded time-dependence of a decrease in the distances between old and new spots. In the

first stage of the outbreak, the beetles migrated over fairly long distances and explored available

resources. The area containing stressed trees that were susceptible to being attacked was quite large. In

later stages, the available resources were more limited, thus the beetles were more likely to attack only

less suitable resources adjacent to old spots. We found that the distances that we measured between

old and new attacked spots were similar to those measured by Wichman and Ravn (2001). Otto and

Schreiber (2001) recorded almost equal distances between the currently attacked spots and the spots

attacked in the preceding years, however, the distances were almost two times further than the

Period II (93-95) Prograd.

0

2

4

6

N

NE

E

SE

S

SW

W

NW

Period III (95-97) Culminat.

0

5

10

15

N

NE

E

SE

S

SW

W

NW

Period IV (97-99) Retrograd.

0

5

10 N

NE

E

SE

S

SW

W

NW

Figure 7.—Direction of spread of spots (ha of damaged area).
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 31

distances that we measured in the Tatra Mountains Time-dependent differences in distances can be

explained by the existence of a lower outbreak intensity, consequently beetles probably had not

utilized the majority of the resources available. The aforementioned authors recorded their distances

in an outbreak that occurred at lower elevations and under climatic conditions that were optimal for

bark beetle development. The outbreak in the Tatra Mountains took place at relatively high elevations

and in an area that is not suitable for outbreaks. The smaller distances that we recorded in the Tatra

Mountains can be explained by the fact that the outbreak area was characterized by high mountain

chains without vegetation that provided a separation between the attacked spots.

The direction in which spots spread was in agreement with Lohberger (1993). Beetles preferred to

attack trees at forest edges exposed to solar radiation. According to Schopf and Köhler (1995), the

main factor influencing the spread of outbreaks is the stress on trees caused by an abrupt increase in

the level of solar radiation. This increase of solar radiation can result from cutting, downing or

defoliation of neighboring trees. Trees on forest edges with a northern exposure were not stressed.

Thus there were almost no attacks spreading in a southerly direction (that means attacks at forest

edges exposed to the North) from initial bark beetle spots.

The increase in the rate of spread of active bark beetle spots during of the course of the outbreak

could be explained by the expansion of old spots over time.

Conclusions

1. The spatial pattern of the spread of bark beetle outbreaks is related to the phase of the outbreak, to

the insolation (incoming solar radiation) of stands on mountain slopes, and – primarily – the

insolation of the individual bark beetle spots.

2. The integration of vegetation change analysis (image differentiation), a digital elevation model,

and information about stand characteristics, provides a reliable method that can be used for mapping

intensive bark beetle outbreaks in mountainous conditions.

3. These results demonstrate the usefulness of such approaches for conducting research on bark beetle

outbreaks in mountain conditions, and for applying forest (nature) protection practices.

Acknowledgments

The research was supported by EU-INCO project: Integrated risk assessment and new pest

management technology in ecosystems affected by forest decline and bark beetle outbreaks, and by

the Grant Agency for Science of Slovak Academy of Sciences (2/1162/21). The authors wish to thank

foresters from both national parks and Eva Lajzová for help with data acquisition and Dr. Kúdelová

for correction of the English grammar.

Figure 8.—Speed in which

active spots spread.

Mean+SD

Mean-SD

Mean+SE

Mean-SE

Mean

Mean=17.268+2.198*x+eps

Period

m / year

0

5

10

15

20

25

30

35

40

II (93-95) Prograd. III (95-97) Culmin. IV (97-99) Retrog.
32 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

References Cited

Capecki Z. 1978. Badania nad owadami kambio- i ksylofagicznymi rozwijającymi się w górskich

lasach świerkowych uszkodzonych przez wiatr i okiść. Prace Inst. Bad. Leśn., 563: 39-117.

Capecki Z. 1981. Zasady prognozowania zagrożenia oraz ochrona górskich lasów świerkowych

przed owadami na tle szkód wyrządzanych przez wiatr i okiść. Prace Inst. Bad. Leśn. Nr 584: 3-44.

Eastman, J. R.; McKendry, J. E.; Fulk, M. A. 2000. Change and Time series analysis. (United

Nations Institute for Training and Research, Explorations in Geographic Information Systems

Technology, Volume 1), Clark University, Worcester, CD.

Grodzki W. 1997. Changes in the occurrence of bark beetles on Norway spruce in a forest decline

area in the Sudety Mountains in Poland. Pp 105-11 in J.-C. Gregoire, A.M. Liebhold, F.M.

Stephen, K.R. Day, and S.M. Salom (Eds.), Proceedings of the IUFRO conference, Integrating

cultural tactics into the management of bark beetles and reforestation pests, Vallombrosa 1-4 september

1996. USDA, Forest Service General Technical Report NE-236.

Jakubauskas, M. E.; Price, K. P. 1997. Empirical relationship between structural and spectral

factors of Yellowstone lodgepole pine forests. Photogrammetric Engineering & Remote Sensing.

63 (12): 1375-1381.

Koreň et al. 2002. Building of a GIS database. In: Integrated risk assessment and new pest

management technology in ecosystems affected by forest decline and bark beetle outbreaks. (Final

report from INCO-Copernicus European research project).

URL: http://www.vsv.slu.se/schlyter/tatry_pr/tatrypr.htm

Lohberger, E. 1993. Zur Populationsdynamik von Ips typographus L. im Nationalpark Bayerischer

Wald: Entstehung und Entwicklung von ausgewählten Befallsflächen im Lusengebiet.

Diplomarbeit der Forstwissenschaftlichen Fakultät der Ludwig-Maximilians-Universität München.

80 pp.

Otto, L. F.; Schreiber J. 2001. Spatial patterns of the distribution of trees infected by Ips typographus

(L.) (Coleoptera, Scolytidae) in the National Park „Sächsische Schweiz” from 1996 to 2000.

Journal of Forest Science, 47 (Special Issue No. 2): 139 - 142.

Schopf, R.; Köhler, U. 1995. Untersuchungen zur Populationsdynamik der Fichtenborkenkäfer im

Nationalpark Bayerischer Wald. In: Biberlriether, H. at al.: 25 Jahre auf dem Weg zum Naturwald.

Passavia Druckerei GmbH, Passau, p. 88-109.

Schwerdtfeger, F. 1955. Pathogenese der Borkekäfer-Epidemie 1946 - 1950 in

Nordwestdeutschland. Schriftenreihe der Forstlichen Fakultät der Universität Götingen und

Mitteilungen der Niedersächsischen Forstlichen Versuchsansstalt. 13/14. 133s.

Stolina, M. 1970. On the problem of indifference of Ips typographus. Zborník vedeckých prác

Lesníckej fakulty VŠLD vo Zvolene. 12 (3): 61-76. (In Slovak).

Wichmann L., Ravn, H. P. 2001. The spread of Ips typographus (L.) (Coleoptera, Scolytidae) attacks

following heavy windthrow in Denmark, analysed using GIS. Forest Ecol. Mgmt, 148: 31-39.

Zemek, F., Heřman, M., Klouda, Z. 1999. Bark beetle calamity assessment from remotely sensed

data. Silva Gabreta. 3: 191-172.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 33

Abstract

Curculionidae developing in the soil of birch stands in an air-polluted region were classified using the

method of soil photoeclectors on the basis of their population dynamics (1986 – 2000) and

phenology of their emergence from where they developed. In the course of 15 years we saw two

evident culminations in the population density of Polydrusus undatus, while the population density of

the other species – Polydrusus (Metallites) impar, Phyllobius arborator, P. argentatus, P. calcaratus,

Rhinomias forticornis and Strophosoma capitatum culminated only once. We derived the sum of

effective temperatures, which characterise the start of activity of a wide range of weevils. Based on the

phenology of emerging from where they developed, the dominant species were those weevil species

that are active in the spring.

Key words: Curculionidae, weevils, photoeclectors, population and seasonal dynamics, birch stands,

Betula pendula Roth

Introduction

The Curculionidae, the most abundant family of beetles in the Czech Republic (900), are generally

found among the phytophagous fauna of birch stands (Betula pendula Roth) (Kula 1990/1991).

Their harmful effect in the study region has not yet made itself felt to such an extent as the willow

leaf beetle, mottled umber moth and winter moth, miners of the genus Eriocrania or the case-bearers

(Kula 1988a, 1988b, 1989, 1990a, 1990b, 1995, 1998, 2000; Kula and Vaca 1995). Despite this,

they include a number of species whose gradation potential is well known so we cannot exclude the

impact of their heavy feeding and clear eating (e.g. of the genus Phyllobius – P. pyri L.) on birch trees

(Axelsson et al. 1973).

Ioannisiani et al. (1970) indicated that humidity had a dominant effect on the population dynamics

of weevils, although the site, stand density, soil quality, degree of coverage of the soil and light

conditions are also important factors.

According to Schauermann (1987), the population density of weevils which develop in the soil is

generally higher under conditions where moderate acid rain occurs. In heavily polluted localities,

birch stands are damaged by Phyllobius arborator (Herbst.), P. calcaratus (Fabr.) and P. pyri, and in the

moderately polluted birch stands by Strophosoma capitatum (Deg.), which undergoes gradation under

these conditions and damages up to 50% of the entire assimilation area (Chlodny 1982, Chlodny

and Styfi-Bartkiewicz 1982). These are not, however, the only species that appear as they could be

accompanied by other species e.g. Polydrusus cervinus L. (Tomkow 1976).

The objective of the present study was to evaluate the population and seasonal dynamics of weevils

which develop in the soil of birch stands that occur in the air-polluted regions of the Děčín

Sandstone Upland (northern Bohemia). Data were collected in the years 1986 – 2000 using the

method of photoeclectors.

Material and Methods

Weevils were collected in six birch stands (Betula pendula Roth) in the forest district Sněžník. In

1986 – 2000, we placed seven soil photoeclectors (1 X 1 X 0.3 m) in each of the 5-7 year old stands;

The Population and Seasonal Dynamics of Weevils Developing in

the Soil of Birch Stands

E. Kula

Institute of Forest Ecology, Faculty of Forestry and Wood Technology, Zemědělská 3, 613 00

 Brno, Czech Republic, e-mail: kula@mendelu.cz
34 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

every year in late March they were moved under the projection of crowns of other birch trees. The

weevils were collected at seven-day intervals during the entire vegetation period (15 April – 30

October) and were preserved in 75% ethanol.

During the 15 years of our investigations, we used several methods of collection (photoeclectors,

ground traps, shaking trees, Moericke’s dishes) and collected 41,686 imagoes of 122 species of

weevils; using photoeclectors we collected 20,131 weevils of 83 species, of which 16,862 specimens

(73 species) were collected in the birch stands. The sum of effective temperatures (SET) applied to

evaluate the onset of activity of the weevils was calculated as the sum of positive temperatures from

the beginning of the calendar year.

Identification of the weevils was accomplished with the assistance of Dr. O. Majzlan, CSc. from the

Faculty of Teaching of Komensky University in Bratislava, Ing. J. Fremuth from Hradec Králové and

R. Stejskal from Znojmo.

Description of the Study Area

The forest district Sněžník is a part of the Děčín Sandstone Upland (northern Bohemia, 14o04 E,

50o

46 N, number of square of net fauna mapping 5250) which for many years had been exposed to

SO2 concentrations of more than 60 μg/m3

. The region lies in a cold mountain climate (average

annual temperature 6o

C, average annual precipitation is 800 mm, length of the vegetation period 110

– 120 days, altitude 450 – 700 m), and is currently under a moderate pollutant load. Large areas of

spruce stands died in 1979 and were subsequently replaced by stands dominated by birch (Betula

pendula Roth).

Results

In the study region, the following weevils were the eudominant species: Polydrusus (Metallites) impar

Des Gozis (10.5%), P. arborator (11.7%), Polydrusus undatus (Fabr.) (12.7%) and P. argentatus (23%).

The dominant weevil species were P. calcaratus (5.6%), Rhinomias forticornis (Boh.) (5.02%) and S.

capitatum (5.17%). Four species were classified as sub-dominant, i.e. Barypeithes mollicomus (Ahrens)

(4.79%), Otiorhynchus (Dorymerus) subdentatus Bach (3.16%), Hylobius abietis (L.) (4.63%) and

Otiorhynchus niger (Fabr.) (2.39%). The other weevils are recedent (3) and sub-recedent species (111).

Population Density of Weevils in the Soil

The imagos of weevils whose larvae develop in the soil emerge from where they developed during the

vegetation period, usually in the spring. The method of soil photoeclectors made it possible to specify

the species spectrum of weevils, their abundance, and the population and seasonal dynamics.

In 1986-2000, using the method of photoeclectors placed in the birch stands, we collected 16,862

specimens of 73 species which is 59.8% of all the fauna of the region. Two species of the genus

Phyllobius (i.e. P. argentatus 34.9% and P. arborator 15.18%) and the species P. undatus (14.81%)

were eudominant. Two species, i.e. P. calcaratus and Strophosoma melanogrammum (Forst.), were

dominant (6.71% and 6.48%, respectively). Only two species, i.e. Otiorhynchus singularis (L.)

(2.61%) and O. subdentatus Bach (3.68%), were classified as sub-dominant (Table 1).

Generally 22 weevil species occurred in the soil in the study region. In some places the incidence of

some of the sub-recedent species (B. mollicomus, P. impar, Simo horticornis Herbst., Otiorhynchus

scaber) was higher.

P. argentatus was the species most frequently captured in the photoeclectors (5,908). Since 1988, the

abundance of individuals leaving emergence sites had increased and culminated in 1993-1996 (21.10

– 32.95 specimens/m2

). After the culmination in 1996, the number of weevils decreased to 1.36

specimens/m2

 and then increased to 7.57 specimens/m2 in 2000 (Table 1).
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 35

Table 1.—Population dynamics of Curculionids in birch stands (1986-2000, photoeclectors, spec/m2)

Species 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 Sum % Avg. 

Barypeithes mollicomus (Ahrens, 1812) 0.00 0.00 0.00 0.00 0.07 0.00 0.07 1.40 0.36 0.83 0.55 0.14 0.17 0.07 0.33 168 1.00 0.267Ceutorhynchus floralis (Paykull, 1792) 0.00 0.00 0.00 0.00 0.07 0.07 2.50 1.05 0.67 0.33 0.02 0.02 0.40 0.00 0.02 217 1.29 0.344

Metallites impar Des Gozis, 1882 0.00 0.00 0.00 0.12 0.02 0.00 0.14 0.24 0.83 0.05 0.36 0.14 0.29 0.12 0.33 111 0.66 0.176Otiorhynchus niger (Fabricius, 1775) 0.00 0.02 0.07 0.26 0.00 0.62 0.43 0.33 0.19 0.31 0.26 0.00 0.00 0.00 0.02 106 0.63 0.168

Otiorhynchus scaber (Linnaeus, 1758) 0.00 0.00 0.00 0.02 0.02 0.17 0.00 0.45 0.38 0.62 0.33 0.24 0.45 0.60 0.93 177 1.05 0.281Otiorhynchus singularis (Linnaeus, 1758) 0.00 0.00 0.00 0.00 0.26 0.19 0.40 1.52 0.86 1.26 0.98 0.71 1.81 1.19 1.29 440 2.61 0.698Otiothynchus subdentatus Bach, 1854 0.02 0.07 0.31 0.60 0.38 1.02 1.36 1.40 1.74 1.40 2.05 1.14 1.31 0.71 1.24 620 3.68 0.984

Phyllobius arborator (Herbst, 1797) 0.05 5.10 1.05 2.26 10.79 5.52 4.67 14.81 8.64 4.17 3.19 0.07 0.10 0.12 0.43 2560 15.18 4.063

Phyllobius argentatus (Linnaeus, 1758) 0,17 1.43 0.00 0.14 0.40 2.76 8.00 21.10 30.79 27.33 32.95 1.36 3.69 2.43 7.57 5885 34.90 9.341Phyllobius calcaratus (Fabricius, 1792) 0.02 3.19 0.50 2.90 0.12 2.71 4.55 2.17 3.83 1.57 2.10 0.05 0.88 1.00 1.33 1131 6.71 1.795

 Polydrusus cervinus (Linnaeus, 1758) 0.00 0.00 0.00 0.00 0.00 0.02 0.05 0.10 0.33 1.10 0.95 0.36 0.17 0.10 0.17 140 0.83 0.222

Polydrusus undatus (Fabricius, 1781) 0,00 0.45 1.02 0.62 0.31 1.14 4.48 2.40 7.55 7.52 4.40 0.52 7.43 6.55 15.07 2498 14.81 3.965

Rhinomias forticornis (Boheman, 1843) 0.00 0.00 0.02 0.02 0.00 0.00 0.00 0.12 0.17 0.29 0.31 0.02 0.83 0.31 1.12 135 0.80 0.214

Rhynchaenus rusci Herbst, 1795 0.00 0.29 0.57 0.45 0.00 0.00 0.00 0.00 0.50 0.10 0.00 0.02 0.21 0.02 0.29 103 0.61 0.163

Simo hirticornis (Herbst, 1795) 0.00 0.00 0.00 0.07 0.07 0.05 0.02 0.31 1.00 0.93 0.67 0.31 0.79 0.71 0.52 229 1.36 0.363

Strophosoma melanogrammum (Forster, 

1771) 0.00 0.02 0.02 0.02 0.00 0.07 0.33 0.71 2.67 2.50 1.14 0.71 1.83 2.88 13.10 1093 6.48 1.735

Tachyerges decoratus Germar, 1827 0.00 0.00 0.00 0.00 0.43 0.24 0.62 0.90 0.00 0.05 0.29 0.00 0.00 0.19 0.00 114 0.68 0.181Trichapion simile Kirby, 1811 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.19 0.14 0.14 1.69 1.76 1.17 214 1.27 0.34

Total 0.57 11.60 4.21 9.98 13.38 15.14 28.71 50.76 63.55 51.52 54.40 6.48 24.26 20.29 46.62 16862 100 26.77
36 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

P. arborator (Herbst) is one of the most abundant species and its population density was very high.

The level of abundance increased in 1987 to 5.1 specimens/m2

 and was followed by a decrease;

during the three-year interval we saw a culmination of 10.79 specimens/m2

 in 1990 and 14.81

specimens/m2

 in 1993. From 1994 the population density of the weevil in the region decreased to

0.07 – 0.43 specimens/m2

 in 2000 (Table 1).

During the 15 year period, no important culmination levels of P. calcaratus (Fabr.) were recorded; the

population density ranged between 0.02 and 4.55 specimens.m-2, although it varied irregularly in

individual years and its abundance was the highest during the period 1991 – 1994 (2.71 – 4.55

specimens.m-2).

After a balanced and low population density in 1987 – 1991 (0.3 – 1.14 specimens/m2

), P. undatus

(Rabr.) was the first species to reach the culmination period in 1992 (4.48 specimens/m2

) and in

1994 – 1995 (7.55 specimens/m2

). After a sudden decrease in 1997, we observed a continuous

growth to a maximum density of 15.07 specimens.m-2 in 2000. This species is a typical representative

in birch stands whose population density varies among respective localities.

S. melanogrammum (Forst.) was captured in the photoeclectors only sporadically during the period

1986 – 1991. Its population density was the highest in 1994 – 1995 (2.67 and 2.50 specimens/m2

respectively) and after two years of recession it culminated at a population density of 13.1

specimens/m2 (Table 1).

O. singularis (L.) was not captured in the photoeclectors until 1990; in 1993 – 2000 its population

density was balanced and ranged between 0.71 and 1.81 specimens/m2

 (Table 1).

O. subdentatus Bach appeared in the study region in each of the 15 years; its population density

increased slightly from 1986 to 1996 (0.02 to 2.05 specimens/m2

) and after that its level was

balanced (0.71 – 1.31 specimens/m2

) (Table 1).

Seasonal Dynamics of Weevils

In terms of phenology, Schauermann (1973) separated the weevils according to the length of life of

the imagos and larval ontogenesis. Based on weevils captured in soil photoeclectors in the Sněžník

forest district, we can distinguish species active in the spring with an evident culmination and

subsequent disappearance of imagos: Hylobius abietis L. (no weevils were reported in the region in the

summer due to the limited number of coniferous stands); Coeliodes rubicundinus (Herbst.),

Rhynchaenus rusci (Herbst.), P. undatus, Anoplus roboris Suffr., Tachyerges decoratus Germ., Trichapion

simile Kirby, P. argentatus, P. calcaratus, O. niger appearing sporadically during the entire vegetation

period; weevils active in the summer include Polydrusus cervinus (L.), B. mollicomus, P. impar, P.

arborator, Simo hirticornis Herbst.; weevils active in the autumn (Acale camelus Fabr.); and weevils

with no evident culmination, but with a changing activity when leaving the soil during the entire

vegetation period (Otiorhynchus singularis (L.), O. subdentatus Bach). In spite of the low population

density of Strophosoma melanogrammum (Forst.) we can define its appearance in spring and autumn

with only a hint of culmination.

Weevils Leaving the Soil Regulated by the Sum of Effective Temperatures

The sum of effective temperatures (SET) differentiates the respective weevil species at the start of

their activity on leaving the soil environment. We saw some differentiation also within the framework

of genera in species that move up into birch crowns. Ioannisiani et al. (1970) reported that the SET

from the egg until the imagoes of P. arborator leave the soil was 1929o

C but they did not define the

individual developmental stages. Based on the results of 15 years of collections using soil

photoeclectors, this species can be expected to appear under an average ambient SET temperature of

574o

C. P. argentatus and P. calcaratus began to be active at SET 456oC and 463oC, respectively, and

the later activity of P. clorpus is expressed as SET 619o

C. The population density of P. pyri in the soil

was not high enough and showed a separate period of activation at SET 255 – 865o

C and 1410 –
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 37

1981oC. The increased incidence of this species in birch crowns did not correspond with its

population density in the soil. Species of the genus Polydrusus belong to the early spring species, i.e. P.

undatus at SET 236o

C (109 – 360oC), while a higher SET characterises the species P. impar (784oC).

A considerably different SET of the species Acalles camelus (Fabr.) and A. commutatus Dieckmann

(480o

C and 1832oC) indicated that both hatching and the subsequent activity were disharmonious.

Only the spring activity of the species A. echinatus (Germar) was derived from the low population

density (388o

C). Members of the genus Anoplus (A. roboris Suff. 280oC) and A. plantaris Naeyen

293o

C) have an identical activity. The imagoes of the species Barypeithes mollicomus (Ahrens) have a

high SET value (903o

C). The early spring species with a low SET value are Ceutorhynchus floralis

(Paykull) (282o

C), Coeliodinus rubicundus (Hbst.) (236oC), Deporaus betulae (L.) (259oC) and

Otiorhynchus niger (Fabr.) (296o

C).

Discussion

The broad spectrum of weevils that develop in the soil of birch stands no doubt create a potential

complex of pests of the root system of plants, but due to the high degree of weed infestation of the

stands, they do not present a very grave danger for the root system. However, insect infestation may

increase and cause defoliation due to the site conditions, which are particularly favorable for the

development of species subsequently moving up into the birch crowns (Phyllobius, Deporaus,

Polydrusus). Members of the genus Phyllobius differed not only in the population density, for instance

23% of the weevil fauna was P. argentatus, but also in the start and duration of increased population

density in the study region in contrast to P. arborator (Kula et al. 2000). With the exception of P.

undatus, no repeatedly increased population density of weevils appeared in the period 1986 – 2000.

In 1997 the incidence of weevils in the soil decreased, and this was confirmed by the limited activity

both over the soil surface and in the crown fauna. In Denmark the hatching of the species

Otiorhynchus singularis takes place from late May to late June (Nielsen 1974), while in Germany the

weevils hatch continuously from April to October and their culmination is quite evident in May and

June (Grimm 1973). The period of hatching in the investigated area corresponded with the data of

Grimm (1973), only the culmination was not so evident. The year-round activity with no

culmination from mid-April to mid-September was confirmed when we used ground traps (Kula et

al. 2000). Spring activity is associated with a relatively low sum of effective temperatures (338o

C).

Nielsen (1974) explained the phenology of the incidence of weevils and stated that P. argentatus

adults made their appearance in late April and early May when the temperature of the soil at a depth

of 3 cm is 7-9o

C. According to Schauermann (1973) activity does not begin until late May to early

July at a soil temperature of 8o

C. The defined shift in the appearance of P. arborator corresponds with

data of Urban (1998). The sum of effective ambient air temperatures defined for the weevil fauna in

birch stands (Kula et al. 2000) contributes to their control and to prognoses of their incidence.

Conclusion

 The weevil fauna (73 species) developing in the soil of birch stands in the air-polluted region

included important phytophagous insects of the genera Phyllobius, Deporaus and Polydrusus, which

damage the assimilation area of birch trees. The population dynamics (1986 – 2000) indicated that,

with the exception of P. undatus, the periodicity of increased population density was greater than five

years. Based on the sum of effective ambient air temperatures, which characterizes the initiation of

weevil activity, we can derive a prognosis of the culmination of weevil incidence in spite of minor

differences due to the discordant development of the larvae.

Acknowledgments

This study was supported with the grant research project No. 308/98:434100005 from the Ministry

of Education and VaV/830/3/00 funded by Ministry of Environment of the Czech Republic and by

the following firms and companies: SCA Packaging ČR s.r.o. in Jílové, Netex and Alcan Děčín

Extrusions s.r.o. in Děčín, District Offices in Děčín, Setuza in Ústí nad Labem, CEZ a.s. Prag,

Čižkovice Lafarge Cement Works, North-Bohemian Mines in Chomutov, Dieter Bussmann in Ústí

nad Labem.
38 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Literature Cited

Axelsson B, Larsson S., Lohm U., Persson T. 1973. Production of larvae of Phyllobius piri L. (Col.,

Curculionidae) in an abandoned field. Ent. scand., 4: 21-29.

Chlodný J. 1982. Uwagi o zagrozeniu przez szkodliwe owady drzewostanów i zadrzewien GOP w

latach 1976-1980. Sylwan, 5: 19-26.

Chlodny J., Styfi-Bartkiewicz B. 1982. Oddzialywanie skazen przemyslowych na zageszczenie

populacji owadów zasiedlajacych mlodniki brzozy brodawkowatej (Betula verrucosa Ehrh.).

Sylwan, 4: 31-39.

Ioannisiani T.G., Lavrova N.K., Birg A.V., 1970. Ecological peculiarities of some species of the

genus Phyllobius Germ. (Coleoptera, Curculionidae) from Byelorussia. Ent. Obozrenye, 49 (4):

800-809.

Kula E. 1988a. Hledisko ochrany v náhradních porostech břízy. Les. práce, 8: 362 - 367.

Kula E. 1988b. The willow leaf beetle (Lochmaea capreae L.) in birch stands. Acta univ. agric., 1-4:

261-307.

Kula E. 1989. Bázlivec vrbový na bříze. Les. práce, 2: 68 - 71.

Kula E. 1990a. Bedrohung der Birkenbestände mit Gelben Weidenblatkäfer (Lochmaea capreae L.).

Wissenschaft Theorie und Praxis, Kolloquium Tharandt-Brno „Ökologie von Schlagflächen und

ihre Weideraufforstung im Immissionsschadgebiet des Erzgebirges“, Neuhausen, 21.-23.9. 1990,

p. 192-199.

Kula E. 1990b. Bázlivec vrbový (Lochmaea capreae L.). Folia, řada B, 64 pp.

Kula E. 1990/1991. The weevil beetles (Curculionidae, Coleoptera) in birch stands. Acta univ. agric.,

řada C, No. 1-4: 5-17.

Kula, E. 1995. Notes on bionomy and control of case-bearer (Coleophora serratella L.). Mitt. Dtsch.

Ges. allg. angew. Ent. 10: 83 - 86.

Kula, E. 1998. Crown fauna of birch stand caterpillars in a pollution area and their population

dynamics. In: M.L. McManus and A.M. Liebhold (eds.) Proc. „Population Dynamics Impacts,

and Integrated Management of Forest Defoliating Insects. USDA Forest Service General

Technicial Report NE-247: 303-310.

Kula, E. 2000. Minovači rodu Eriocrania škůdci břízy s gradačním potenciálem. J. For. Sci. 46 (1):

27-33.

Kula, E., Vaca, D. 1995. Pouzdrovníček stromový (Coleophora serratella) v porostech břízy imisní

oblasti. Les - Lesnická práce, 10: 12-13.

Schauermann J. 1987. Tiergesellschaften der Wälder im Solling unter dem Einfluss von

Luftschadenstoffen und künstlichem Säure- und Düngereintra. Verhandlungen der Gesellschaft

für Ökologie (Giessen 1986), Band XVI: 53-62.

Tomkow M.J. 1976. Entomofauna olszy szarej i czarnej (Alnus incana Mnch. i Alnus glutinosa

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53-58.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 39

Abstract

The larvae of Tomostethus nigritus F. (Hym.: Tenthredinidae) began causing severe defoliation on ash

along avenues and tree lines in Zagreb, Croatia since 1997. The phenomenon of population

outbreaks in periurban and urban environments is known but poorly documented in the literature;

the fact that it has not yet been recorded in Croatian forests has spurred authors to investigate further

into this natural event. Populations achieved outbreak levels in the second year after defoliation was

first recorded. Although only Fraxinus excelsior L. was attacked; palatability tests indicate that larvae

show no preference among several ash species, larval development in situ and their dispersion in the

field suggest that phenology of the host tree was the dominant factor in host selection. Based on

foliage availability, F. excelsior proved to be the most suitable species for females during their

oviposition period. Detailed study of all developmental stages, especially the late larval and prepupal

stages, confirmed earlier published knowledge on this sawfly but provided also some new facts and

practical solutions that can be utilized for monitoring and managing this species. Parasitoid fauna

have also been studied and, despite the relatively small impact that was recorded from laboratory

rearings, it is assumed that parasitoids and floods are the most important natural controlling factors

affecting this species in forests. Based on the spread and intensity of the recent outbreak and its

similarity to European outbreaks, we presume that environmental factors, mainly the impact of late

fall and early spring floods, are the most important trigger mechanism involved in this phenomenon.

Introduction

In terms of their ecological and economic value, the lowland forests of pedunculate oak (Quercus

robur L.), narrow leaved ash (Fraxinus angustifolia Vahl), and several other hardwood species are the

most valuable components of forests in Croatia. Based on the tree species composition and forest

structure, these forests are natural or very close to natural as is the fauna that thrives in them.

Common ash (Fraxinus excelsior L.) grows on drier and higher sites, and along with F. pennsylvanica

Marshall is commonly planted as an amenity tree. Periodic outbreaks of common forest pests are well

monitored in the area so the first dramatic signs of ash defoliating caused by T. nigritus aroused

interest among forest entomologists who were concerned about the threat it could pose to these

valuable tree species.

After the initial taxonomic problem due to absence of adult stages, it was identified as T. nigritus F.

(Hym.: Tenthredinidae). It was first detected on F. excelsior planted along an avenue in Zagreb,

Croatia in 1997 and has not appeared in forest stands as was the case in some European countries

(Liška 2000, Holuša pers. comm.). Mrkva (1965) reported that it completely defoliated up to 50 ha

of mixed or pure ash stands while Liška (2000) and Liška and Holuša (2001) reported that T. nigritus

defoliated almost 800 ha of mixed and pure ash stands during the years 1999 and 2000. However,

Austara (1991) and Hrašovec and Diminić (2000) documented that this species occurs in urban

areas. In a recent faunal review of Croation sawflies Perović and Leiner (1991) include this species in

the checklist with available loci occurring in only a part of the country. As noted in some older

European works (Escherich 1942, Mrkva 1965) T. nigritus is a widely distributed Euroasian species

which occurs at very low densities and occasionally reaches higher population levels.

Our research on this species was stimulated by the occurrence of new outbreak loci in urban areas

and by some reports that a similar pest was causing serious damage on ash species in forest and

Spread and Character of Tomostethus nigritus F. Outbreaks in Croatia

During the Last Decade

Dinka Matošević1, Boris Hrašovec2 and Milan Pernek1

1

Forest Research Institute, Jastrebarsko, Croatia

2

Faculty of Forestry, University of Zagreb, Croatia
40 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

periurban stands in northern Italy (Stergulc, pers. comm.) The main goal of our research was to

devise monitoring techniques, possibly predict population trends, determine why outbreaks were

initiated in urban habitats, and to test available suppression methods in the urban environment.

Material and Methods

The biology and development of the sawfly was studied both in the laboratory and in the field. In

order to monitor closely some details of embryonic, larval and prepupal development, freshly laid

eggs, larvae and cocooned eonymphs and pronymphs were brought to the laboratory and reared

under various ambient conditions.

In the laboratory, palatability tests were conducted whereby young leaves of three ash species, F.

excelsior, F. angustifolia and F. pennsylvanica were offered to young larvae of T. nigritus in petri dishes

(20 larvae/dish); leaves were changed daily. A total of 100 larvae were reared on each tree species. The

same trial was conducted in larger insectariums where 100 larvae were reared collectively on foliage of

each of the three ash species. F. angustifolia was included in this experiment because of the relative

importance of this species; F. pennsylvanica was chosen because it was obviously not being attacked in

the area of massive outbreak, whereas F. excelsior, the most severely attacked ash species in the field,

served a s a control.

Laboratory and field trials were conducted on various larval stages using applications of four

chemical pesticides (two IGR products, a pyrethroid, and neem oil) in order to determine the most

appropriate method of suppressing this pest in urban and possibly forest environments.

The incidence of parasitism and species involved were checked in the field and by rearing various

developmental stages but mainly the cocooned eonymphs or pronymphs. One hundred earthen

cocoons were collected during February 2002 and placed in glass vials. After parasitoids emerged, the

rest of the apparently non-parasitized cocoons were dissected to determine the occurrence of other

possible mortality causing factors. Also, insect nets were used to capture the massive swarming of

parasitoids that occurred in the ash crowns during the peak of larval feeding.

Results

Most of the findings of Mrkva (1965) regarding the biology and development of T. nigritus were

verified by our research. There are expected differences regarding phenology since in our climate, the

adults started swarming much earlier and larval feeding peaked and was completed by the beginning

of May throughout our period of monitoring. This is approximately one month earlier than what

was reported in central Europe. In Croatia we consider that T. nigritus is a monophagous species

because F. excelsior is the only species of ash with which it is synchronous phenologically; the

perfectly conditioned leaves of F. excelsior are attractive to the swarm of T. nigritus and to the females

which oviposit on the margins of newly emerged foliage. Both visual and chemical clues could be

involved in the selection of oviposition sites by female sawflies.

We made observations on larval development and conducted morphmetric studies to determine the

number of larval instars. Color of the larva changes through its development. First instar larva,

whitish or almost hyaline, during eclosion emerges from the swollen chamber on the leaf margin, and

molts soon after into the second larval instar which has a greenish cast as the gut fills with leaf

chloroplasts. Later instars become more light green with even light coloured ventral parts. The most

conspicuous change happens after the last larval molt when larva changes to an olive green color just

before descending from the tree and prior to spinning its cocoon. Dynamics of defoliation is typical

and quite dramatic as the developing larvae consume proportionately more foliage; what appears

initially as a moderate episode of defoliation becomes total defoliation over a period of several days.

Under these conditions, a large number of larvae are often unable to complete their development and

die due to starvation. It is interesting to note that even under these conditions, larvae would not

disperse and feed upon the foliage of nearby F. pennsylvanica.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 41

A plot of the measurements of head capsule width and larval length indicate that there are five

distinctive larval instars (Fig. 1). In this research we did not distinguish between male and female

developing larvae as Mrkva did (1965), nor are we certain that he included the measurement of the

last descending instar in his study. The head capsule widths for the 5th larval instar in Mrkva (1965)

vary between 1.87 and 2.06 mm which is clearly larger than our results for the last feeding instar,

therefore there is a need for additional measurements in order to clarify the description of larval

instars.

The last larval instar observed (in this study it was referred to as the 5th larval instar), olive green in

colour, stops feeding, descends the trunk and enters the soil. Larvae don’t go too deep into the soil

which, in our study site was a compacted managed grassland. As described by Mrkva (1965), they

concentrate in the vicinity of the root collar and form shiny, black parchment-like cocoons covered

on the outside with earth. They transform into enonymphs and most of them later become

pronymphs. Pupae were found by mid March and adult emergence began in late March and early

April. The period of massive swarming varied from year to year but usually peaked in mid April.

Palatability tests indicated that there were no preferences among the three ash species tested and that

all larvae reared in both series of tests devoured the foliage and completed their development

successfully. It should be noted however that because of difficulties in obtaining the first instar larva,

only second and partially third larval instars were collected and fed. Mortality of reared larvae could

not be observed.

Beginning in 1998, laboratory and field trials were conducted in order to determine the best possible

way of suppressing T. nigritus populations with chemical pesticides. All tests conduced under

laboratory conditions gave satisfactory results and results differed only in the time lag between the

application of the products and first symptoms of larval intoxication. Four commercially available

chemicals were tested: NOMOLT SC (a.s.teflubenzuron 150 g/l), BONUS SC

(a.s.alphacypermethrin/teflubenzuron 40/120 g/l), SOxJA (neem oil) and FASTAC SC

(a.s.alphacypermethrin 100g/l) which was used as the control. Based on operational success, market

availability, and legislative restrictions on the use of chemical treatments in urban areas, we selected

NOMOLT SC for field use and since 1998 it has been applied annually. The success of the

applications has varied. It was influenced by the efficiency of the equipment, in terms of good crown

coverage and droplet distribution, and correct timing of application. In the context of this research

the applications are considered as additional impact factors which obscured the otherwise more

natural dynamics of the population.

On February 21, 2002, 100 cocoons were collected in the field and placed individually into glass

vials. After a period of three month, they were dissected and provided the following results: 57

cocoons were empty of filled with earth, 19 cocoons were parasitized, 8 contained live enonymphs or

pronymphs and 16 contained dead and dried enonymphs (due to fungi and other unidentified

Figure 1.—Body length and head

capsule width of 199 selected T.

nigritus larvae.





















  	 
    	























	
























42 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

causes). The parasitism rate, calculated on the basis of 43 cocoons bearing either dead or live sawfly

or parasitoids was 44%. All emerged parasitoids belong to the Ichneumonoidea and are not yet identified.

Taxonomic identification of the parasitoids collected in earlier years (netted during swarming in the

crowns) is still in the progress, however preliminary results revealed that two ichneumonids, Synoecetes sp.

Főrster and Ctenopelma sp. Holmgren were most numerous; less numerous were other ichneumonids

belonging to the subfamily Ctenopelmatinae and three species of braconids.

Discussion

Information on the biology of T. nigritus combined with the results of the palatability tests so far,

support our suggestion that this sawfly can be regarded as a monophagous pest of F. excelsior in

Croatia. For this research, it was important to determine if T. nigritus larvae feed equally well on F.

angustifolia. Narrow leaved ash is an important tree species in valuable lowland forests in Croatia and

the threat of defoliation by T. nigritus could pose a serious threat. Though larvae reared in the

laboratory fed well on all three ash species the situation was markedly different in the field. The most

important determining factor based on our observations was the synchrony in phenology of the

insect with that of its candidate host plant. Successful oviposition was critically dependant on the

availability of emerging foliage. At the time of adult eclosion and later swarming, only the F. excelsior

trees provided foliage at the required development stage. Even within the same tree species, there was

a significant variation in individual phenology which resulted in variation in the oviposition rates and

subsequent defoliation. It is suggested that the pronounced variation in tree phenology within the

same ash species is caused by the induced effect of the prior years defolition. We observed that trees

which were totally defoliated in previous years leafed later in the following year. Other ash trees that

occurred in proximity to the attacked F. excelsior trees were left almost untouched. Although we are

not sure of the different scenarios that may exist in other locations, in the area where the outbreak

took place during the past 6 years, only F. excelsior was affected. It is still possible that T. nigritus

could successfully thrive on F. angustiflia at other locations but in that case some other suppressive

factors might be involved in keeping the insect population at low levels.

Regarding the spatial and temporal distribution of larval stages and postembryonic development, it is

of practical interest to note that it is quite common to have almost all larval instars present at the

same locality at the same time. This is due to the intraspecies diversity in tree phenology. This

complicates the timing of application of suppression tactics and is the most important factor that

contributes to inconsistent results of the treatments. Early appearance of the egg laying females and

insufficient leaf area available for spray deposits also contribute to application problems. Among the

chemicals tested, both IGR compounds appeared to be effective however the treatments had little

impact on the ongoing outbreak and complicated interpretation of the research data. Investigation of

the parasitoid community was expected to reveal some clues into the regulation of T. nigritus

specifically what causes the decline in populations. However the parasitism rates were not as high as

was reported by Mrkva (1965). He reported parasitism rates as high as 80% and stated that even a

20% rate was considered as adequate to cause the population decline and eliminate the need for

spraying. The parasitism rate obtained in our monitored population was less than 50% and this level

did not seem to have any effect on sawfly populations. It’s very possible that repetitive chemical

treatments had detrimental effects on the parasitoid community. At the same time, ineffective

treatments only partially reduced T. nigritus populations which might have contributed to the

continuation of the outbreak itself (Speight and Wainhouse 1989).

Although flooding was not a regulating factor in our study site, it has been documented to be an

important factor by other authors (Mrkva 1965, Liška 2000, Liška and Holuša 2001). In all

described cases of T. nigritus outbreaks occurring in forests, one thing was common-they were al

semi-natural or natural forest types located in riparian zones. In the undisturbed and periodically

flooded forests of this type, it is normal to have at least two flood seasons-late fall to winter and in the

spring. Species of Fraxinus are naturally accustomed to this excessive surface water and thrive well in

these conditions. It is also known that the floods can have a negative impact on some populations of

forest arthropods that occur in the soil or litter including some serious forest pests (Schowalter 2000).

Excessive moisture in the soil during a portion of the year could heighten the impact of pathogenic
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 43

fungi thus enhancing the mortality of arthropod populations. Presumably, the high levels of flood

water during adult emergence in spring could also serve as a source of mortality; all of these parameters

might have a significant role in regulating some other pest populations in these forests (Hrašovec

1993). Competitive adaptation is a mechanism that enables insect populations to escape the niche

during the flood period through its adaptive biology (as is the case with another tenthredinid sawfly,

Apethymus filiformis Klug). Absence of floods in these habitats might alter the existing equilibrium

and, in the case of T. nigritus populations, could be the triggering mechanism for outbreaks.

In conclusion we emphasize that we lack considerable knowledge about population dynamics of this

sawfly, especially the role of natural enemies. The fact that it rarely (if ever) occurs in Croatian forest

habitats and thrives obscurely at low population levels, hinders the pace of research. Additional

studies of the dynamics of the natural populations will be needed in order for us to assess the

potential threat of this sawfly on Croatian forests.

Acknowledgments

We would like to thank Franjo Perović, Croatian Natural History Museum in Zagreb, for his help

during taxonomic validation of the T. nigritus, Csaba Thuroczy, Systematic Parasitoid Laboratory in

Koszeg, for his help in parasitoid identification, Jaroslav Holuša, Forestry and Game Management

Research Institute in Jílovišté-Strnady, on supplying the valuable literature references, and Suzana

Videc, for her valued contribution in the field and laboratory work.

References Cited

Austara, O. 1991. Severe outbreaks of the ash sawfly Tomostethus nigritus F. (Hymenoptera,

Tenthredinidae) on ornamental trees in Oslo. Anzeiger für Schadlingskunde, Pflanzenschutz und

Umweltschutz 64 (4): 70-72.

Escherich, K. 1942. Die Forstinsekten Mitteleuropas. Bd. 5, Paul Parey Verlag, Berlin.

Hrašovec, B. 1993. Prilog poznavanju bioekologije insekata iz roda Balaninus Germ., štetnikažira

hrasta lužnjaka (Quercus robur L.). Glasnik za šumske pokuse 29: 1-38.

Hrašovec, B. and D. Diminić. 2000. Pests and diseases of trees in continental urban areas in

Croatia – current status and future trends. In: International Symposium on Plant Health in Urban

Horticulture; Braunschweig, Germany, May 22-May 25 2000, Mitteilungen aus der Biologischen

Bundesanstalt für Land- und Forstwirtschaft, Heft 370: 63-68.

Liška, J. 2000. Listožravý hmyz, pp.24-31. In M. Knížek and P. Kapitola [eds.], Výskyt lesních

škodlivých činitelů v České republice v roce 1999 a jejich oekávaný stav v roce 2000. Zpravodaj

ochrany lesa 2000 (suplementum): 1-62.

Liška, J. and J. Holuša. 2001. Listožravý hmyz, pp.28-38. In P. Kapitola and M. Kní•ek [eds.],

Výskyt lesních škodlivých činitelo v České republice v roce 2000 a jejich očekávaný stav v roce

2001. Zpravodaj ochrany lesa 2000 (suplementum): 1-74.

Mrkva, R. 1965. Prispevek k morfologii, bionomii a poznani parazitu pilatky jasanove (Tomostethus

nigritus F.). Prace vyzkumnych ustavu lesnickych, ČSSR, svazek 30, Zbraslav-Strnady: 35-64.

Perovič, F. and S. Leiner. 1996. Index of the Sawflies Sensu lato (Hymenoptera, Symphyta) of

Croatia. Natura Croatica 5(4): 359-381.

Schowalter, T. D. 2000. Insect Ecology – an Ecosystem Approach. Academic Press. San Diego.

Speight, M. R. and D. Wainhouse. 1989. Ecology and Management of Forest Insects. Clarendon

Press, Oxford.
44 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

The significance of microsporidian pathogens as mortality agents of gypsy moth (Lymantria dispar

L.) in Europe frequently is overlooked. Collections of isolates from 10 different countries suggest that

three genera and several biotypes are extant. It is important that the taxonomic placement and

phylogeny of currently described genera and species be clarified and that regulatory issues be

addressed before exotic entomopathogens are introduced into North America to regulate L. dispar

populations.

Introduction

Microsporidia are a diverse group of obligate intracellular parasites that use most animals and

humans as hosts. They are among the oldest eukaryotes and have many primitive yet uncommon and

complex characteristics. At the molecular level, they possess a ribosomal RNA structure that is

thought to be more prokaryotic than eukaryotic. Microsporidia have no mitochondria and undergo a

primitive nuclear division (Vossbrinck et al. 1987), though sequence analysis of several

microsporidian genes suggest that they are fungi (Weiss et al. 1999; Van de Peer et al. 2000).

Microsporidia were elevated to the phylum Microspora by Sprague (1977) and amended to the

Phylum Microsporidia by Sprague and Becnel (1999). According to Larsson (1999), about 1,300

species have been described but a substantial number of identified genera and species have not been

studied or named. The genus Microsporidium was introduced by Sprague (1977) as a temporary

designation for species that have been excluded from other genera and are awaiting proper taxonomic

classification based on new information.

The taxonomy of microsporidia—specifically, their identification in field collections—has been

hampered by their size (typically 2-10m) and because few species have been described adequately and

placed in appropriate genera (Larsson 1999). It is estimated that about half of microsporidian genera

contain only a single species. The advent of electron microscopy and recent advances in molecular

technology have improved the systematics of microsporidia but also raised questions about the

taxonomic placement and phylogeny of currently described genera and species.

According to Maddox et al. (1999), six species of microsporidia have been described from gypsy

moth populations in Europe, and several isolates that have not been described or identified are

recorded in the literature. Despite a rich microsporidian complex in European gypsy moth

populations, microsporidia have not been reported from gypsy moth populations in North America

(McManus et al. 1989). Table 1 is an updated version of the information provided initially by

Maddox et al. (1999).

Of the listed species, probably only N. lymantriae (Weiser 1957) and N. serbica (Weiser 1964,

Pilarska and Vavra 1991) satisfy the diagnostic criteria defined by the International Code of

Zoological Nomenclature (1985) for describing a new taxon. With respect to the identification of the

other species, it should be noted that ultrastructural and molecular information was not available to

the authors at the time these microsporidia were described as new species

Microsporidian Pathogens in European Gypsy Moth Populations

Michael L. McManus1and Leellen Solter2

1

United States Department of Agriculture, Forest Service, Northeastern Center for Forest Health

 Research, 51 Mill Pond Rd., Hamden, CT USA

2

Center for Economic Entomology, Illinois Natural History Survey, 607 E. Peabody Dr.,

 Champaign, IL USA
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 45

Importance of Microsporidia in Gypsy Moth Population Dynamics

In Central Europe, the gypsy moth is considered a periodic pest, with outbreaks occurring every 7-10

years. Further south in the Mediterranean and Balkan regions, where the climate is more conducive

to gypsy moth development and survival, outbreaks are reported every 3-4 years (Weiser 1987).

In Europe, several entomopathogens have been reported from L. dispar populations particularly

during outbreak years (Weiser 1987). These include the baculoviruses (nuclearpolyhedrosis virus

(NPV) and granulosis virus (GV), cytoplasmic polyhedrosis virus (CPV), microsporidia, fungi,

bacteria, and nematodes. In North America, where the gypsy moth was introduced in 1869, NPV is

the dominant pathogen causing outbreak populations to collapse. Bacteria, nematodes, and CPV are

recovered only occasionally; microsporidia have not been recovered. In 1989, the fungus

Entomophaga maimaiga, which was introduced in 1910-11 from Japan but never reported as

established, was found simultaneously in several locations in the northeastern United States and

subsequently caused a regional epizootic in U.S. gypsy moth populations (Hajek et al. 1995). Since

then, E. maimaiga has been the most dominant mortality factor in preoutbreak populations and acts

in a density-independent manner, which is atypical of most entomopathogens.

Among the pathogens in European gypsy moth populations, NPV is primarily responsible for the

termination of L. dispar outbreaks whereas microsporidia are prevalent during the gradation period

prior to outbreaks and then persist at low levels among gypsy moth populations in the years between

outbreaks. Whereas the NPV causes acute disease and results in dramatic epizootics among mid-and

late-instar larvae, microsporidia usually produce a chronic disease state that results in the death of

some larvae and pupae and prolongs the developmental period of larvae, possibly lengthening the

window of opportunity for early-instar parasitoids such as Cotesia melanoscela and Glyptapanteles sp.

Weiser and Novotny (1987) reported that hymenopteran parasitization of the gypsy moth was 58%

higher in plots treated with N. lymantriae than in control plots.

Different microsporidian species that infect the gypsy moth target different tissues within their host,

including the silk glands, midgut epithelium and associated muscle tissue, fat body, Malpighian

tubules, nerve tissue, and reproductive organs. Species in the genus Nosema infect the gonads and

ovarioles, reducing fecundity and killing overwintering embryos. Zelinskaya (1980) reported that the

Table 1.—Microsporidia Described or Reported from European Gypsy Mothsa

Microsporidian species Location Reference

Nosema lymantriae Czechoslovakia Weiser (1957)b

Nosema muscularis Czechoslovakia Weiser (1957)b

Nosema muscularis Spain Romanyk (1966)

Nosema muscularis USSR, Ukraine Zelinskaya (1980)

Nosema serbica Yugoslavia Weiser (1964)

Nosema serbica USSR, Ukraine Zelinskaya (1981)

Nosema serbica Bulgaria Pilarska and Vavra (1991)

Thelohania disparis Russia Timofejeva (1956)

Thelohania similis Czechoslovakia Weiser (1957)b

Nosema portugal Portugal Maddox et al. (1999)b

Nosema sp. Portugal Cabral (1977)

Nosema sp. Yugoslavia Sidor (1979)

Nosema sp. Romania Saftoiu et al. (1978

Endoreticulatus Portugal, Bulgaria, Hungary Solter et al. 1997

a

Modified from Maddox et al. (1999).

b

Species descriptions.
46 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

mortality of overwintering eggs laid by severely infected females was 58.5% compared to 34.2% in

healthy females. Survival rates for neonates that emerged from infected egg masses also were reduced

significantly.

According to Weiser (1987), microsporidian infections become more prevalent in the progradation

period prior to a gypsy moth outbreak and may infect 15-30% of the population during an

outbreak’s peak period. As soon as the NPV appears in the population, microsporidian prevalences

decline. However, many researchers suggest that microsporidia might have a more significant role in

the population dynamics of L. dispar. Purrini and Skatulla (1978) reported that the prevalence of N.

lymantriae in Sardinia reached 60% in1977. Sidor and Jodal (1983) studied the prevalence of a

microsporidia identified as N. serbica, and NPV in the Acacia Forest “Bagremara” during a gypsy

moth outbreak in 1978-81. The average larval mortality attributed to N. serbica exceeded that caused

by NPV in each of the 4 years of the investigation and reached a maximum of 72% in 1978 when the

estimated density of L. dispar was 16,000 egg masses/ha. Zelinskaya (1980) concluded that a complex

of four microsporidian species was the major cause of a decrease in the population of I-III instar

gypsy moth larvae in forest plantings along the lower Dnepr River in the Ukraine during 1976-77,

and that 26-60% of egg-laying moths were infected during the outbreak phase. Sierpinska (2000)

reported a prevalence of infection of 91% among late-stage L. dispar larvae that were sampled from

the Biebrza National Park in Poland. Larvae were infected by a Nosema-like microsporidium.

Strong evidence that microsporidia are significant mortality factors in the dynamics of gypsy moth

populations in Central Europe was the motivating factor behind a foreign exploration program that

was initiated in 1985. The long range objective was to explore the feasibility of introducing candidate

microsporidia from Europe as classical biocontrol agents to enhance the natural control of gypsy

moth in North America.

Published Description of Species

In 1986, the USDA Forest Service supported a foreign exploration trip to Europe by J. Maddox and

M. Jeffords (Illinois Natural History Survey) to search for microsporidian isolates from gypsy moth

populations (McManus et al. 1989). Isolates were recovered from Portugal and the Czech Republic; a

description of the microsporidium recovered from Portugal was published (Maddox et al. 1999).

Included was a tabular listing for six species of microsporidia that were described or reported from

European gypsy moth population at that time (Table 1).

The original description of these microsporidia contained few ultrastructural details and little data on

life cycles. This lack of information led to confusion in identifying microsporidia isolated from

Lepidoptera because some species are dimorphic (Maddox and Sprenkel 1978), i.e., they produce

two different types of spores. Unfortunately, the microsporidia from the gypsy moth in Europe were

described before dimorphism was recognized. Consequently, species reported in the literature as

mixed infections of Thelohania sp. and Nosema sp. probably represent a single dimorphic species in

the genus Vairimorpha. According to Sprague et al. (1992), the formation of uninucleate spores in an

octosporous sporulation cycle is characteristic of Vairimorpha. Figure 1 shows the probable

relationships among the described species of gypsy moth microsporidia.

Nosema lymantriae: Probably a valid species as described by Weiser (1957). Mention in the

literature of mixed infections of Nosema and octosporous Thelohania, though probably refers to

a different species in genus Vairimorpha.

Thelohania similis: Probably not a valid species and always was reported as mixed with

diplokaryotic spores (Nosema type) spores, suggesting a Vairimorpha sp. No Thelohania sp. has

been recovered in our surveys of microsporidia in European gypsy moth populations.

Thelohania disparis: Close examination of the description in Timofejeva (1956) leads us to

believe that this is a Vairimorpha sp.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 47

Nosema muscularis: Its description matches the characteristics of “primary spores,” an

autoinfective stage that apparently occurs in all lepidopteran Nosema and Vairimorpha species as

well as in other microsporidia genera (Solter and Maddox 1998a).

Endoreticulatus sp: The status of this species and its synonomy with Pleistophora schubergi, which

was described from Euproctis chrysorrhoea (L.), is being investigated. The isolate from Portugal

was first referred to as Vavraia sp. (McManus et al. 1989), but later was called Endoreticulatus

sp. (Solter et al. 1997). It has since been recovered from L. dispar populations in Bulgaria and

Hungary.

Nosema serbica: It is not known whether this species is similar to or conspecific with N.

Lymantriae; unfortunately, neither isolates nor stained slides are available for analysis. Pilarska

and Vavra (1991) discussed the similarities and differences between N. serbica and N.

lymantriae. Attempts are being made to isolate this microsporidia from gypsy moth populations

in the Balkans from where it was described originally.

Nosema portugal: First reported by Cabral (1977) and later isolated and described in detail by

Maddox et. al. (1999) this species is closely related to other Nosemas isolated from gypsy moth

populations. However, on the basis of molecular data, it may stand as a distinct species.

Ultra structural and molecular studies have been completed on isolates of Vairimorpha sp. recovered

from gypsy moth populations in Bulgaria. A report is being prepared that describe this species and

clarifies the taxonomy of the species listed in Table 1.

Foreign Exploration in Search of Microsporidian Isolates

As mentioned earlier, a foreign exploration program was initiated by the Forest Service in 1993 with

support provided by the USDA Foreign Agricultural Service, International Cooperation and

Development Research and Scientific Exchange Division, to search for microsporidia among gypsy

moth populations in several countries in Europe, to compare these isolates with previously described

species, and to evaluate isolates that might be candidates for introduction as classical biological

control agents against L. dispar populations in North America. Although gypsy moth populations

were at low densities throughout most of Europe during the period of exploration, we recovered

microsporidian isolates representing three genera from more than 20 locations in seven countries. All

of the isolates are stored in liquid nitrogen at the Illinois Natural History Survey laboratory of the

junior author.

Figure 1.—Relationships of gypsy moth microsporidia.
48 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Since 1994, an ad hoc team of 10 scientists from six countries has conducted research on various

aspects of several of the isolates that we recovered: ultrastructure and life cycle, modes of

transmission, effects of infection on the gypsy moth host, impacts on nontarget Lepidoptera, and

molecular sequencing of small subunit rDNA. A synthesis workshop was held in Prague in October

1997 and attended by 12 scientists from the United States and Europe to report results of individual

studies, exchange relevant data, and identify laboratory and field research that is needed to realize

accomplishments in a reasonable period of time. Much of the progress that is documented here

resulted from the combined efforts of workshop participants.

Related Research

Since the stated goal of the research program was to evaluate the feasibility of introducing

microsporidia into U.S. gypsy moth populations as a classical biological control agent, a basic

knowledge about their host specificity is fundamental in resolving safety and regulatory issues

(Maddox et al. 1992). A series of laboratory bioassays was initiated in 1994 that elucidated the host

range of five of the biotypes listed in Table 1 by testing larvae of 49 lepidopteran species that are

indigenous to North America and sympatric with gypsy moth larval populations (Solter et al. 1997).

The microsporidia produced a variety of responses in the nontarget hosts such that the latter were

placed in one of three categories: (1) no infection (refractory); (2) a typical infection in which few or

no typical environmental spores were produced and horizontal transmission is unlikely; (3) heavy

“host-like” infections in which mature environmental spores are formed that may be infective to

conspecific individuals. On the basis of the response of nontarget species to the five microsporidian

biotypes, Solter et al. (1997) concluded that N. portugal was the least infectious to nontarget

Lepidoptera, and that Endoreticulatus sp. was most infectious, producing a “host-like” infection in 15

different species. The other isolates, Nosema-like isolates from Slovakia and Romania and N.

lymantriae, were intermediate in infectivity to lepidopteran larvae, but host ranges and responses of

hosts to infection were closer to those of N. portugal than to Endoreticulatus sp. The infectivity of

Endoreticulatus sp. is not surprising. Although it has been recovered from gypsy moth populations in

Portugal, Hungary, and Bulgaria, Endorecticulatus sp. is considered a generalist; its taxonomic

placement is under study.

Solter and Maddox (1998b) conducted studies to determine the usefulness of laboratory studies in

predicting ecological host specificity by feeding microsporidia isolated from other Lepidoptera to L.

dispar larvae and then comparing the horizontal transmission between infected and uninfected L.

dispar larvae to that which occurs among individuals of the natural hosts. Although nine

microsporidian species infected L. dispar larvae, only one was transmitted to uninfected L. dispar

larvae. This supports the concept that there is a much higher level of ecological host specificity

among Lepidoptera microsporidia than laboratory host-range studies might predict.

Although laboratory bioassays provided a method to assess the host range of microsporidia in

sympatric populations of Lepidoptera, there was a need to accumulate supporting data on the

presence and prevalence of L. dispar and other microsporidia from natural populations of

Lepidoptera in the field. Long-term monitoring of L. dispar populations in several sites in central and

western regions of Bulgaria revealed that three species were present (Endoreticulatus sp., Nosema sp.,

Vairimorpha sp.) and that the same species were recovered repeatedly from the same site (Solter et al.

2000). Eleven microsporidia isolates from the same three genera were recovered from 1494 insect

larvae representing 12 families of Lepidoptera. However with one possible exception, none of these

isolates produced a typical host-like infection when fed to L. dispar larvae. The infective isolate was

genetically different from the local endemic microsporidium. That no L. dispar microsporidia were

found in Lepidopteran larvae feeding sympatrically with gypsy moth larvae on the same host-tree

species supports predictions from laboratory studies that the ecological host specificity of L. dispar

microsporidia is much narrower than physiological (laboratory) host specificity.

More definitive studies being conducted in Slovakia to evaluate the infectivity of N. portugal and

Vairimorpha sp. against nontarget Lepidoptera when the isolates are applied to control gypsy moth
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 49

larval populations. In this multiyear study, suspensions of each isolate are applied via ULV spray in

replicated 500-m2

 plots to which gypsy moth larvae had been introduced previously. There were

intensive collections of all larval Lepidoptera 7 and 14 days after spraying. Preliminary results suggest

that the Vairimorpha isolate is more infectious to nontarget Lepidoptera, particularly certain genera of

noctuids, than N. portugal. These results corroborate the results of laboratory studies of Solter et al.

(1997), though additional field studies will be conducted in subsequent years to better clarify the

impacts of these two isolates.

As mentioned earlier, a recurring dilemma concerning microsporidia, including the gypsy moth

isolates, is related to their taxonomic placement. Many of the morphological and life-cycle characters

that traditionally were used in microsporidian systematics are not holding up to molecular scrutiny,

and other new techniques are elucidating characters such as multiple spore types in some species that

understandably confused early taxonomists. Nevertheless, pathogens identification is a necessary

component of a classical biological control program where exotic organisms are being considered for

release into the environment. From analyses of ribosomal DNA sequences we know that the gypsy

moth Vairimorpha and Nosema species are taxonomically distinct from the type species (Nosema

bombycis from silk moth and Vairimorpha necatrix from the true army worm), and that gypsy moth

Nosema and Vairimorpha isolates are more closely related to each other than to other members of the

genera to which they are assigned. While there are sufficient differences between the gypsy moth

Nosema and Vairimorpha isolates to designate them as good species groups, the Nosema group

continues to be difficult to analyze. The rDNA sequences (both large and small) are nearly identical

between isolates but most differ by one base pair. The rDNA sequence may be too conservative to

analyze differences in closely related species or distinguish differences between populations. The

problem is twofold: to which of the previously described species are they most closely related (or are

they synonymous), and do they represent one variable species or several species?

We will need to rely on the extant records (the literature and Giemsa-stained specimen slides) to

determine whether our isolates are synonymous with previously described species. However, to

evaluate relative differences between our viable isolates, we are experimenting with PCR-RAPDs. In

preliminary studies we have been able to distinguish definitive differences between Vairimorpha sp.

and Nosema spp. as well as certain differences between the Nosema isolates. We are not yet certain that

this method will yield the information we seek and will consider using AFLP or protein analysis in

future studies. Overcoming the taxonomic difficulties within these groups will allow us to take more

positive steps toward satisfying the regulatory issues that must be addressed before an exotic

entomopathogen is introduced into North America to control gypsy moth populations.

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52 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

Analysis of data on the population dynamics of foliage browsing insects in time and space was

conducted in the Ukraine. For each of the main species, correlation indices were calculated between

outbreak characteristics (mean and specific foci area, outbreak probability), weather elements (air

temperature, precipitation), indices (hydrothermal coefficient, winter severity) and the dates of air

temperature transition over and below different limits (0, 5, 10, and 15°C).

The population dynamics of insects with different types of seasonal development depends on

peculiarities in insect seasonal development and in particular, on weather conditions of the region.

For insect species which hibernate in the egg stage (Tortrix viridana, Neodiprion sertifer, Lymantria

dispar), the initiation of outbreaks occurs more often in years when larval feeding begins early.

Outbreaks of insect species that hibernate in the larval stage (Dendrolimus pini, Euproctis chrysorrhoea)

often follow years when dry and hot weather occurs during the period when young larvae are feeding

at the end of the summer.

Outbreaks of insect species that hibernate in the pupal stage begin in years following after the

occurrence of an early spring (Panolis flammea) or a dry and hot June (Bupalus piniarius) and are

associated with conditions that promote the rapid development of young larvae.

The occurrence of outbreaks of insect species whose feeding takes place at the end of the season are

also associated with warm and dry weather during the feeding period which promotes synchrony in

the completion of their seasonal development with completion of the period of vegetation by the host

tree.

Introduction

Analysis of many years of data suggests that not all foliage browsing insects cause outbreaks of mass

propagation (Meshkova 2002a) and that the dynamics of different geographical and ecological

populations is not the same (Meshkova 1999, 2001b, 2001e).

Differences in the spread of geographical population foci indicate that it depends on certain indices

which are rather stable for separate regions (Meshkova 1999). In our opinion, such indices are not

only air temperature, precipitation and hydrothermal indices, but also the dates and rates of the

annual course of air temperature (Meshkova 2001c; 2001d).

Our observations on the foci of different foliage browsing insects show that occurrence of an early

spring is favorable for survival of the spring complex of larvae (Meshkova 2002b; 2002c).

According to phenological theory (Meshkova 2002a), the most frequent and intensive outbreaks of

foliage browsing insects in the South are associated with an early production of host-tree vegetation

in the Spring and acceleration of insect development due to temperature. In conditions of a more

continental climate (that is evaluated as the difference in air temperature between July and January)

east of the Ukraine, air temperature increases rather fast in the spring however soil temperature

increases rather slowly. Hatching of larvae is dependent on air temperature but bud break begins only

after the soil thaws and translocation of water in the stems begin. Therefore in the East, larval hatch

Dependency of Outbreaks Distribution from Insects-defoliators’

Seasonal Development

Valentina Meshkova

Ukrainian Research Institute of Forestry & Forest Melioration, meshkova@u-fri.kharkiv.com
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 53

coincides with the occurrence of the youngest leaves which have a high nitrogen content and almost

no protective substances (phenols, tannins). In the West, larval hatch coincides with more developed

foliage that has accumulated protective substances, due in part to high availability of water in stands

in these regions.

Differences in the intensity and frequency of outbreaks of different insect species were supposedly

dependent on peculiarities in their seasonal development. The main foliage browsing insect species

were classified into four groups (Meshkova, 2001a) that differ mainly by their overwintering stage:

group 1 – egg (larvae feeding in spring), group 2 – larvae (feeding in spring and at the end of

vegetation (autumn)), for example Dendrolimus pini L., Euproctis chrysorrhoea L.), group 3 – pupae

(feeding in spring or in summer-autumn), and group 4 – eonymph (feeding in summer-autumn, for

example, Diprion pini L.). Subgroups differ by the terms of diapause: subgroup 1a – development

from egg to egg without diapause, summer diapause of eggs transits to winter diapause (Tortrix

viridana L.); subgroup 1b – summer diapause of pupae or eonymph, swarming in autumn, winter

diapause of eggs (Operophthera brumata L., Neodiprion sertifer Geoffr.); subgroup 3a – summer

diapause of pupae transits to winter diapause (Panolis flammea); subgroup 3b – winter diapause of

pupae transits to summer diapause (Bupalus piniarius L.).

The objectives of this study were to analyze the history and geography of insect outbreaks in the

Ukraine and to determine what combinations of weather conditions are most favorable for different

insect species.

Methods

We assumed that if weather conditions that are favorable for certain insect populations can occur in

some years in one point, then there are regions where such situations occur more often.

We calculated the correlation coefficients between climatic indices including air temperature,

precipitation, hydrothermal coefficients for different months, indices of winter severity, dates of late

spring and early autumn frosts, dates of stable transition of air temperature over and below different

limits (0, 5, 10, and 15°C) and indices that characterize foliage browsing insects outbreaks, the

probability of outbreaks, mean annual foci area, and specific annual foci area (Meshkova 1999,

2002c).

Such correlation indices were calculated on the one hand for mean data for many years on weather

elements and on insect outbreaks for 25 points within the Ukraine, and on the other hand for a

single point, Kharkiv for the period 1894 –2001.

Data on the history and geography of insect outbreaks were obtained from the literature, archives of

the Ministry of Forest Management (later – State Committee of Forest Management of Ukraine), the

laboratory of forest protection of Ukrainian Research Institute of Forestry & Forest Melioration, and

from our own investigations. Meteorological indices were obtained from respective electronic data

bases. Data for 1894–1999 were obtained from the Kharkiv regional meteorological Center.

Statistics were calculated with the help of standard computer programs (Microsoft Excel 5.0. and

Statistica 4.3 for Windows). The reliability of coincidence for insect outbreak years and certain

weather elements was estimated using c2

 criteria (Rokitskij 1973).

Results

The foci area for Tortrix viridana L. covers more than half of the area that contains foci from all leafbrowsing insects. There is a significant correlation in the probability of its outbreaks with latitude

(r=-0.41; P=0.05), longitude (r=-0.67; P=0.01), continentality (r=-0.57; P=0.05), suggesting that

outbreaks occur more often in regions with higher air temperature and lower precipitation during the

vegetation period. There is also a high correlation with indices that characterize the integral influence

of temperature and precipitation (r=-0.75; P=0.01).
54 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

The probability of T. viridana outbreaks is higher in regions where the dates of the last spring frost

occur earlier (r = -0.49; P=0.05) and there is a stable transition of air temperature over 10° (r = -0.58;

P=0.05) with a shorter interval between the dates of stable transition of air temperature over 0° and

15° (r = -0.51; P=0.05), 5° and 10° (r = -0.54; P=0.05); This means that outbreaks are more frequent

in the regions that experience more early springs and shorter periods of larval feeding.

When we take into account data over many years at one point (Kharkiv, 1894–2000), we often see

the coincidence of years with earlier larval hatching and years of high larval density (r=-0.53;

0.01<P<0.05) as well as an increase in foci area (r=-0.42; P=0.05). This means that the early hatch of

larvae is favorable for T. viridana populations.

For Lymantria dispar L. there is a negative relationship between latitude and foci area (r= -0.64;

P=0.05), latitude and outbreak probability (r= -0.63; P=0.05). Dependence of outbreak probability is

reliable for longitude (r=0.54; P=0.05) and the continentality index (r=0.52; P=0.05). This means

that the more favorable conditions for gypsy moth populations occur in the East and South of

Ukraine.

There is a positive correlation between gypsy moth foci area and air temperature in January (r=0.62;

P=0.05) and in Autumn – in September (r=0.44), October (r=0.56; P=0.05), November (r=0.57;

P=0.05), December (r=0.59; P=0.05). This suggests that the most favorable conditions for gypsy

moth populations occur in those regions with a warm autumn. These conditions are favorable for

eggs to complete their embryonation and to enter diapause.

The most high and reliable (P=0.01) correlation of gypsy moth outbreaks probability is related to the

months from May to September (r=0.7; r=0.8; r=0.82; r=0.8; r=0.72), and then becomes lower for

October (r=0.54; P=0.05). Negative dependence of outbreak probability with latitude agrees with its

positive dependence on temperature. This means that warm conditions in the south are favorable for

gypsy moth populations.

There is an explanation for the positive correlation of specific foci area with the sum of negative

temperatures for the period with negative air temperature (r=0.52; P=0.05). The natural selection of a

specimen, that enters a deep diapause earlier is more intensive in regions with colder winters.

The negative correlation of mean (r= -0.49; P=0.05) and specific (r= -0.62; P=0.05) foci areas with

precipitation for periods with negative air temperature and a positive correlation with index of winter

severity (r=0.46 and r=0.4 respectively) can be associated with a weakening of host plants that occurs

in frosty dry winters.

There are negative correlations between annual precipitation, for periods with positive temperature

and monthly temperature over 10°C and gypsy moth specific foci area (r=-0.62; r=-0.50 and r=-0.55

respectively) and with probability of outbreaks (r=-0.68; r=-0.67 and r=-0.7 respectively). This

suggests that conditions are more favorable for gypsy moth outbreaks in regions with less

precipitation.

There is a negative correlation between gypsy moth foci area and precipitation in almost all months

except December and January, but the correlation is highest in August (r= -0.53). The correlation

coefficient between specific areas and monthly precipitation are highest for July (r = -0.7) and August

(r = -0.67) but they are also reliable at P=0.05 for April (r = -0.64), May (r = -0.6), June (r = -0.6),

and September (r= -0.53). The most significant (P=0.01) correlation coefficients between

precipitation and probability of gypsy moth outbreaks occur for the months of July (r= -0.8), August

(r= -0.8) and September (r= -0.78), but they are rather high also for April (r= -0.63), May (r= -0.6),

June and October (r= -0.56). The high correlation between air temperature and precipitation in JulyAugust and indices characterizing gypsy moth foci is probably related to the influence of weather

conditions during the period of oviposition and embryonation.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 55

It is clear that integral indices which characterize periods of drought are also correlated negatively

with the spread of gypsy moth foci (correlation indices for mean, specific foci area and outbreak

probability with hydrothermal coefficient of vegetation period are r = -0.4; r = -0.62 and r = -0.79

respectively).

A negative correlation was found between the probability of gypsy moth outbreaks and the date air

temperature over 10° stabilizes in the spring (r=-0.62; P=0.05). This means that occurrence of an

early spring is favorable for development of gypsy moth outbreaks.

For Neodiprion sertifer Geoffr., a reliable but moderate positive correlation was found between

specific area and air temperature during the vegetation period (r=0.55–0.58; P=0.01). The correlation

of mean, specific foci area and outbreak probability with precipitation is negative. The correlations

are negative between mean area and April precipitation (P=0.05; r = -0.47), and highly significant

(P=0.01) between specific area with precipitation in April (r = -0.64) and July (r = -0.59). The

correlation between mean area and precipitation in other months is reliable at P=0.05. Negative

correlation coefficients were calculated between Neodiprion sertifer mean and specific foci area and

precipitation for the year and vegetative season, and for the hydrothermal coefficient.

The negative correlation calculated between specific foci area and outbreak probability with the dates

when stable air temperatures over 5° occurs in spring (r=-0.61 and r=-0.47) and 10° (r = -0.56 and r

= -0.58) suggests, conditions are favorable for N. sertifer survival in regions where spring begins

earlier.

The correlation is positive between the date when the transition of air temperature below 15° in

autumn is stable with both specific area (r=0.58; P=0.05) and outbreak probability (r=0.58; P=0.05).

This means that conditions are more favorable for outbreaks of N. sertifer in areas where the

transition of air temperature below 15° occurs late in the autumn. The correlation between outbreak

probability and intervals between the transition of stable air temperature in autumn below 15° and

10° (r = -0.64; P=0.05), 15° and 5°C (r = -0.66; P=0.05) is higher. This suggests that shorter intervals

are better for Neodiprion sertifer populations. It is during this time that the pronymphs change into

pupae, and when adults swarm and lays eggs.

Outbreaks of N. sertifer in the Kharkiv region coincide with those years when the date of stable

transition of air temperature over 10°C is earlier than 23.IV (χ2

=10.6; P<0.01). The reliability is even

higher when this occurs earlier than 16 April (χ2

=11.3; P<0.01).

The probability of Euproctis chrysorrhoea L. outbreaks is higher in the south (r=-0.53 with latitude). A

positive dependence with longitude is calculated for specific foci area (r=0.64) and outbreak

probability (r=0.67; P=0.05); this means that outbreaks of this pest occur more often and with

greater intensity in the East of Ukraine. The same dependence is determined for continentality index

which increases from the West to East (r=0.74 and r=0.58 for specific foci area and outbreak

probability respectively).

The probability of E. chrysorrhoea outbreaks correlates reliably with air temperature in May (r=0.67;

P=0.05), June (r=0.76; P=0.01), July (r=0.80; P=0.01), August (r=0.77; P=0.01) and September

(r=0.6; P=0.05). Influence of air temperature on E. chrysorrhoea outbreak probability increases from

spring to summer, and is maximal during the period of moth flight and when neonate larvae appear.

This can be explained by the fact that survival of neonate larvae is essential in the life cycle of this

species, which appear almost simultaneously in different points of area (Meshkova 2001). Rapid

development of eggs within a short time period promotes species survival. At locations with higher

July temperatures, insect development accelerates and therefore from a geographical perspective, we

see such changes of correlation coefficients by months. The beginning of larval feeding (that

coincides with initiation of spring) and completion of larval feeding (that coincides with completion

of the vegetation period) varies strongly in different regions. Therefore the correlation of air

temperature with E. chrysorrhoea outbreak probability is less for the early spring or autumn months.
56 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

A negative essential correlation is determined between E. chrysorrhoea outbreak probability and

precipitation for the vegetation period (P=0.01). Correlation indices for July, August and September

(r = -0.71; r= -0.8; r = -0.8) indicate that conditions are more favorable for the development of young

larvae in locations where there is less precipitation during this period.

The correlation index for E. chrysorrhoea outbreak probability and hydrothermal coefficient for

vegetation season is -0.79 (P=0.01). This supports the notion that the growth of outbreak probability

occurs under dry conditions. The negative influence of winter severity coefficient on outbreak area

(r=-0.51) suggests that E. chrysorrhoea foci spread more in regions with low winter precipitation and

low temperature, that is in the regions characterized with low host plant resistance.

The probability of E. chrysorrhoea outbreaks is higher in the regions where the date of air temperature

transition below 15° (r=0.64) occurs later.

Analysis of many years of data for Kharkiv (1894–2000) shows that the mean hydrothermal index for

July is equal to 0.1±0.006. It is equal to 0.09±0.01 in the years of outbreaks and to 0.07±0.01 in

previous years. Coincidence of E. chrysorrhoea outbreaks with the years following after years when the

hydrothermal index for July is less than 0.09 is significant with a probability of 99.9% (χ2

=10.3).

For Dendrolimus pini L, there is a positive correlation with foci area and April air temperature

(r=0.71; P=0.05) (this is the period when larvae begin feeding after hibernation) as well as with air

temperature during August–October (r – 0.65–0.68), which is the period of young larval feeding. We

found a high correlation of specific foci area with annual year temperature (r=0.69).

There is a negative correlation of specific foci area with precipitation for most months (March – -

0.72; April – -0.68; June – -0.65; July – -0.67; August – -0.68; October – -0.71; November – -0.7;

December – -0.69). There is also a negative correlation of specific foci area with the hydrothermal

coefficient (r=-0.69). This suggests that localities with low precipitation are more favorable for

D. pini.

The reliable correlation of winter precipitation with D. pini foci specific area (r=0.67) can be

explained by the fact that high water content in the litter during thaws causes the spread of infection

by fungi among larvae. On the other hand, when the snow layer is dense, thaws occur slowly and

larvae begin feeding later.

We determined that there is a negative correlation of indices that characterize D. pini outbreaks with

the date of the last spring frost (r = -0.63; P=0.05) and a positive correlation (r=0.64) with the date of

the first autumn frost. There is also a positive correlation (r=0.69) between mean and specific foci

area with the number of days with air temperature over 5°C. This suggests that weather conditions

are more favorable to D. pini survival in those regions that are characterized by an early beginning

and late completion of warm weather. These conditions promote the rapid development of older

larvae after winter and neonates at the end of the season.

A high correlation index was estimated for the interval between dates of air temperature transition

over 5° and 10°C with D. pini mean (r=0.63; P=0.05) and specific (r=0.71; P=0.05) foci area. It is

during this period that larvae initiate feeding after hibernation. The correlation between specific foci

area and the interval between the dates of air temperature stable transition below 5° and 0°C in

autumn is also reliable (r=0.68; P=0.05). This is during the period when winter diapause of D. pini

caterpillars begins.

The correlation of indices that characterize dates and rates of spring development in the Kharkiv

region (1894–1999) with the dynamics of D. pini populations in the Kharkiv region indicates that

85.7% of outbreaks begin in the years when the stable transition of air temperature over 0°C occurs

before 21. (χ2

=4.0; P>0.1), and 92.9% of outbreaks occur in the years when stable transition of air
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 57

temperature over 5°C occurs before 10.IV (χ2=3.7; P>0.1). This means that 78.6% of outbreaks

occur in the years when the interval between stable air temperature transition over 0 and 5°C is not

less than 16 days (χ2

=3.7; P>0.1); 71.4% of outbreaks occur in the years when the interval between

stable air temperature transition over 5 and 10°C is not less than 18 days (χ2

=6.5; P=0.04). This

means that an early spring with slow development and uniform soil thawing and initiation of pine

vegetation in the stand promotes high quality forage for caterpillars and is favorable for survival of D.

pini populations.

Years with higher air temperature are favorable for D. pini populations because a greater portion of

larvae will begin hibernation in later instars. During 1894–2001 in the Kharkiv region, 92.9% of D.

pini outbreaks began in years when the sum of positive air temperatures during July-September was

over 1664°C (χ2

=11.9; P<0.01), and 71.4% outbreaks began in years when the July temperature was

over 20.7°C (χ2

=4.2; P>0.1).

For Panolis flammea L., there is a positive correlation of mean foci area with the date of stable air

temperature transition over 0°C (r=0.58) and a negative correlation with the date of such transition

in autumn. The correlation is higher for mean foci area and when the interval between dates of air

temperature stable transition is over 0° and 5°C (r=-0.81), and between dates of air temperature

stable transition over 0° and 10°C (r= -0.77. This suggests that a rapid increase of air temperature in

the spring is favorable for swarming, mating, egg laying and their development.

It was stated that 77.8% of P. flammea outbreaks in the Kharkiv region between 1894–2001 occur in

cases when air temperature transition over 0°C in the previous year occurred not later than 17.

(χ2

=5.5; P>0.05). Thus 88.9% of outbreaks begin when stable air temperature transition over 5°C in

the previous year occurs before 5.IV (χ2

=6.9; P=0.03), and transition over 10°C occurs before 23.IV

(χ2

=8; P>0.02).

The influence of high temperatures on caterpillar development and their survival is confirmed by the

fact that 88.9% of P. flammea outbreaks in the Kharkiv region occur after years when the mean air

temperature in May is over 15°C (χ2

=4.5; P>0.1) and 55.6% of outbreaks began in the years

following those years when the hydrothermal coefficient for June was less than 0.05 (χ2

=6.3; P<0.05).

The length of P. flammea larval development varied from 26 to 44 days in different years. In 1998

(before the last outbreak), it was 30 days, while in 1999 it was 32 days. In 2000, development

required 36 days because of relatively cold temperatures in May; the mean air temperature was

approximately 13°C. The larval feeding period did not exceed 34 days in years when outbreaks were

initiated (x2

=4.6; P=0.01).

For Bupalus piniarius L., there is a reliable correlation (P-0.01) of specific foci area with precipitation

in the winter months of December, January and February (r=0.89; r=0.98; r=0.76). This can be

explained by the beneficial effect of additional snow cover on the survival of pupae. There is a

moderate correlation (P=0.05) between the probability of B. piniarius outbreaks and precipitation of

other months (r=-0.51 – r=-0.74). This is indicative of the preference by this species for mesophytic

conditions. B. piniarius outbreaks occur more often in areas with more humid conditions unlike

most other foliage browsing insects; in the Ukraine, outbreaks occur in the background of other

species i.e. pine sawflies and are of short duration.

The correlation between B. piniarius specific foci area with the date of air temperature transition over

0° is positive (r=0.73; P<0.05). This suggests that conditions are more favorable for B. piniarius

outbreaks in regions where spring begins later. This may be related to the requirement by larvae for a

certain soil humidity that is optimal for their survival.

An analysis of the change in autumn temperatures in different regions indicates that a later decline in

temperature is favorable for B. piniarius populations (r=-0.82).
58 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

The absence of a significant correlation between B. piniarius outbreaks and the change in spring

temperature for many years observations in the Kharkiv region (χ2

<1) can be explained. Larvae of B.

piniarius browse the previous year’s foliage which is suitable for feeding long before the swarming of

moths occurs. Therefore a shift in the date of swarming does not have an effect on the conditions

required for larval feeding.

A positive correlation (P=0.05) of Diprion pini L. was found between specific foci area and air

temperature in March and April (r=0.51 and r=0.53 respectively); this may be related to the influence

of spring conditions affecting the termination of diapuse and on the emergence of imagos.

There is good correlation (r=0.59; P=0.05) between specific foci area with air temperature during the

vegetation season (period with air temperature over 10°C); this is explained by the occurrence of two

D. pini generations per year in the south, while there is only one generation in the north. A negative

correlation was found between specific foci area with the date of air temperature stable transition over

5° (r=-0.63) reflecting the beneficial effect of an early spring for D. pini.

There was a significant positive correlation between the probability of D. pini outbreaks with

precipitation in January (r=0.6; P<0.01); this may be related to the fact, that snow cover is favorable

to the survival of cocoons the litter. There is a negative correlation between specified foci area with

the hydrothermal coefficient for the vegetation period (r = -0.48) suggesting that there is an increase

in D. pini populations in regions with less humidity.

In the Kharkiv region, 76.5% of D. pini outbreaks occur in those years when the transition of stable

air temperatures over 10°C occurs before 23.IV (χ2

=8.2; P=0.015); 100% of outbreaks occur in those

years when the transition occurs before 30.IV (χ2

=5.1; P>0.05), and 88.2% of D. pini outbreaks

occur in the years when the transition is before 20.V (χ2

=12.8; P<0.01).

The initiation of outbreaks occurs when air temperature in May and June (16.3°C and 20°C

respectively) exceeds the mean data for many years (15.4°C and 19°C respectively). For the period of

1984–2001 in Kharkiv, 94.1% of D. pini outbreaks began in years when the air temperature in May

exceeded 14°C (χ2

=3.7; P>0.1), and 82.4% of outbreaks began in years when the air temperature in

May exceeded 18°C (χ2

=2.3; P>0.1).

In the years when outbreaks began, first generation of cocoons of D. pini were formed before 17.VI

in 88.2% cases (χ2

=12.2; P<0.01). The majority of first generation larvae complete feeding before the

solstice (when photoperiodic reaction begins to have a dominant influence on developmental temps).

The larvae that do not complete their development before this date often continue development after

the monovoltine type. The occurrence of a larval diapause in summer allows larvae to complete their

development in September simultaneously with larvae from the summer generation.

We did not find a reliable correlation between outbreaks and hydrothermal indices for the summer

generation feeding period. However in 70.6% of the years when D. pini outbreaks occurred, the

hydrothermal index in August did not exceed 0.08 (χ2

=2.0; P>0.1).

All D. pini outbreaks in the Kharkiv region occurred in years when the stable transition of air

temperature below 5°C occurred after 20 October (χ2

=5.9; P=0.05).
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 59

Discussion

A reliable correlation was found between the beginning of outbreaks caused by foliage browsing

insects and terms and temperature during the seasonal development of these species.

For species that hibernate in the egg stage (1st group – Tortrix viridana, Lymantria dispar, Neodiprion

sertifer), the beginning of outbreaks coincide with the time when larval feeding begins.

For the 2nd group (hibernate as larvae), the initiation of Dendrolimus pini outbreaks coincides with

high air temperature in June-September of the current year, while for Euproctis chrysorrhoea, it

coincides with low hydrothermal coefficient in July of the previous and current years.

Panolis flammea outbreaks (the 3rd group, which hibernate as pupae) occur in years following after

those years with an early transition of air temperature over 0, 5 and 10°C. High air temperature in

May (over 15°C) of the current year and low hydrothermal coefficient in June (below 0.1) of the

previous year are less coincident with outbreaks of Panolis flammea. Outbreak of Bupalus piniarius

coincide with high air temperature in July of the previous year and to a lesser degree with high air

temperature in September of the current year.

The beginning of Diprion pini outbreaks (the 4th group, hibernate as enonymphs) reliably coincide

well with years when an early transition of air temperature over 10°C occurs.

Estimated correlation of dates and rates of the course of annual temperature with the dissemination

of foliage browsing insects in different regions of the Ukraine allows us to obtain data to support a

suggested phenological theory of population dynamics (Meshkova 2002a). The dates and rates of the

development of all foliage browsing species that feed during first part of the vegetation period (before

the solstice) depend on the course of temperatures. Dates and rates of the development of those

foliage browsing insects that feed during the last part of the vegetation depend on the photoperiodic

reaction of organisms which complete their seasonal development coincident with completion of the

vegetation period of their host.

Foliage browsing insect outbreaks occur more often and are intensive in the South because:

–insects develop more rapidly at higher temperature

–tree resistance (general, and to insects) declines at low humidity

–at the absence or insignificant soil chilling to the date when larval feeding begins, the sap of

host plants begins to move earlier in spring; therefore the needles of the previous year become

more suitable for larvae of Neodiprion sertifer and Dendrolimus pini, while the development of

current needles (for Panolis flammea ) and budbreak of deciduous trees (for leaf-feeding larvae

of the spring complex) is accelerated.

Outbreaks of foliage browsing insects occur more often and are more intensive in the East because:

–stands are more resistant in the East regions that have high precipitation, which causes slowing

of larval development and a decline in their survival

–in the East regions with high continentality index, the occurrence of colder winters and hotter

summers ( as compared to West regions) cause a rapid increase in air temperature in the spring

which results in acceleration of larval development. This is favorable for insect populations

–in the East regions there is optimal difference in the rates of air and soil heating, which allows

larvae to consume the most suitable foliage immediately after hatching.
60 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

References cited

Meshkova V. 1999. Forest pests outbreaks prognosis on the base of climatic factors analysis, pp.74–

79. In Beat Forster, Milos Knizek, Woiciech Grodzki [eds.], proceedings, Methodology of Forest

Insect and Disease Survey in Central Europe (Second Workshop of the IUFRO Working Party

7.03.10. April 20–23, 1999, Sion-Chateauneuf, Switzerland). Swiss Federal Institute for Forest,

Snow and Landscape Research, Birmensdorf, Switzerland.

Meshkova V. 2001a. Classification of forest pests-defoliators in ukraine by the types of their seasonal

development. Biology & Valeology: Scientific papers. Kharkiv: Kharkiv State Pedagogical

University. 4: 81–87 [In Ukrainian].

Meshkova V. 2001b. Global and local factors in the forest insect defoliators eruptions in Ukraine,

pp.72–77. In Methodology of Forest Insect and Disease Survey in Central Europe: Proc. Third

Workshop of the IUFRO WP 7.03.10. Romania.

Meshkova V. 2001c. Phenological prognosis of Neodiprion sertifer Geoffr. for different zones of

Ukraine. Problems of forest ecology and forest use in Polissya of Ukraine. Zhitomir: Volin 2 (8):

125–130 [In Ukrainian].

Meshkova V. 2001d. Prediction of the seasonal development of the gold-tail moth Euproctis

chrysorrhoea L. Proceedings of National Agrarian University. 46: 164–171 [In Ukrainian].

Meshkova V. 2001e. Spatial dynamics of forest insects-defoliators in Ukraine. Third Balkan

Scientific Conference «Study, Conservation and Utilisation of Forest Resources»: Proceedings (2–6

October 2001, Sofia).– Sofia. –V.III: 78–85.

Meshkova V. 2002a. History and geography of foliage browsing insect pest outbreaks. Kharkiv:

Majdan. – 244 p [In Ukrainian].

Meshkova V. 2002b. Spring development dates and Tortrix viridana L. population dynamics.

Proceedings of Kharkiv National Agrarian University («Entomology & Phytopathology») 3: 133–

140 [In Ukrainian].

Meshkova V. 2002c. The role of spring beginning dates in pest-defoliators outbreaks development.

Forestry & Forest Melioration 101: 15–19 [In Ukrainian].

Rokitskij P.F. 1973. Biological statistics. Visheisha Shkola, Minsk.– 320 p.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 61

Abstract

Procedures for obtaining data about the sanitary state of forests in Russia are discussed briefly. The

single parameter of official statistical accounts is the area of forests that have been killed or that serve

as foci for pest and disease outbreaks. However, this scant information allows us to observe the

variation over time of forested areas that have been killed by several unfavorable factors: insects, wild

fauna (ungulates and rodents), diseases, weather, and human activity. The dynamics of outbreaks of

the most important needle- and leaf-eating insects in the Russian territory from 1990-2001 are

discussed.

Materials and Methods

Forms of Compulsory Statistical Accounts Related to Forest Pathology

The composition of generalized data about disturbances in the state of Russian forests is determined

by the form of statistical accounts approved by the State Statistical Committee of Russia. All subjects

of the Russian Federation (RF) are obliged to provide information on the use of forest protection, the

areas of forests that have been killed in total and by individual causal agents, along with the data on

areas of foci of forest pests and diseases. This form, “the dynamics of areas of killed stands and foci of

pests and diseases (ha) in the territory of the Russian Federation,” designated as “Form No. 12”

(within the list of all affirmed forms of statistical accounts) must be utilized by all forestry enterprises.

These data are published annually in the “Protection of Environment” issued by the State Statistical

Committee of Russia, in the State Reports about the Condition of Environment of Russia and its

Regions, issued by the Ministry of Natural Resources, and are also presented periodically on the web

site of the Ministry.

This information is the only official source available and is absolutely necessary for one to understand

the general ecological situation in Russian forests and to document areas of distribution of all

disturbances caused by biotic, abiotic and anthropogenic factors. The value of these data can be

enhanced further by adding data about monitoring the impact of forest pathogens; these data will be

collected in the future.

Table 1 is a shortened version of the compound table containing statistical data on areas of stands

killed by different factors of unfavorable impact (FUI) and areas of foci of pests and diseases over last

12 years (1990-2001). Data about forest protection measures (lines 01-11), and some other lines

which contain no useful information (for example, line 20, area of foci of pests + diseases, line 35, the

total area of foci of certain pests including such different species as wood-eating pests, chafers, bark

bugs, and others) have been eliminated.

Some explanation about the rules for filling out Form Νο. 12 is necessary in order to interpret that

data that are presented. Line 12, the total area of stands killed, also includes the area of killed forest

plantations, the area of dead stands to be felled in the course of a clear sanitary cutting, and stands

destroyed by forest fires and other FUI; (lines 13-19) the main causes of dieback in stands; line 16

includes the area of stands killed by unfavorable weather conditions (drought, frosts, changing the

water-table level, wind throw, snow breakage); in the last case instead of “ wind throw, snow

Dynamics of Foci of Forest Pest Insects in Russia over the Last Decade

E. G. Mozolevskaya1, I. A. Utkina2*and L. S. Matusevich3

1

Department on Ecology and Forest Protection of the Moscow State University of Forest

2

The Institute for Forest Science of the Russian Academy of Sciences

3

Department for Forest Fund Protection of the Administration of Conservation, Protection

and Reproduction of Forest Fund, Ministry for Natural Resources of the Russian Federation
62 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 Table 1.—The area of stands killed and the area of pest and disease foci, by years (103 ha)* Parameters 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 12. All dead stands, including those killed by 158.5 419.3 492.1 171.2 274.5 162.1 515.1 254.3 279.2 299.5 699.8 486.4 13. ... pest insects 2.4 8.9 19.2 13.2 25.4 78.4 194.5 3.0 3.1 3.6 20.3 15.5 14. ... wild animals. 13.3 9.3 9.3 3.9 5.3 4.5 1.0 1.5 1.1 0.2 1.2 0.7 15. ... diseases 0.7 1.9 1.4 0.8 1.1 1.9 3.5 2.2 5.1 6.0 5.5 11.3 16. ... weather conditions 45.0 184.7 86.9 19.6 15.9 22.9 24.2 18.6 15.3 20.1 33.6 11.0 17. ... forest fires 95.4 213.4 313.1 131.6 225.3 53.1 291.0 227.8 245.9 268.4 637.4 127.1 18. ... anthropogenic factors 1.6 1.2 62.2 2.2 1.4 1.5 0.8 1.1 8.7 1.2 1.9 161.4 19. ...including industrial pollution 0.6 0.3 61.8 1.1 0.3 0.6 0.2 0.1 0.1 0.1 0.1 159.5 The area of foci of pests and diseases 20. Needle-eating insects, including 292.7 868.4 342.3 198.5 458.5 892.1 449.8 333.0 358.7 373.6 6518.4 10181.5 21. ...Dendrolimus sibiricus 4.2 84.6 140.9 12.2 145.1 574.8 245.6 81.7 120.8 152.3 6257.6 6858.5 23. ... Dendrolimus pini 5.2 12.0 7.0 6.3 11.4 11.0 8.4 10.4 8.7 9.3 23.8 3.2 24. ... Lymantria monacha 59.7 23.5 53.0 37.7 27.6 24.4 24.3 41.2 49.6 61.9 73.7 36.9 25. ... Bupalus piniarius 11.7 12.0 11.0 16.7 149.9 36.2 5.3 21.1 17.7 5.6 4.6 140.1 26. ... Panolis flammea 0.6 0.3 0.4 0.3 0.2 0.6 0.3 3.3 11.2 3.0 31.0 45.1 27. ... Diprion pini 18.0 9.0 22.3 22.3 18.9 34.9 21.4 24.2 10.8 14.7 11.9 9.6 28. ... Neodiprion sertifer 105.3 55.4 40.6 53.9 35.8 67.5 29.5 85.4 56.6 50.2 39.4 51.4 29. ... Acantholyda stellata 27.3 32.8 32.4 35.9 42.5 8.1 ... Boarmia bistortata 67.8 4.0 0 0 0 0 30. Leaf-eating insects, including 1021.4 1832.5 716.0 1045.5 1351.9 1070.4 1624.8 1671.2 1084.1 974.1 623.2 1217.9 31. ... Lymantria dispar 479.7 1379.6 265.9 421.3 1078.7 855.2 1427.1 1310.8 755.8 571.5 238.6 985.4 32. ... Euproctis chrysorrhoea 27.9 7.8 6.2 4.9 1.3 0.8 5.7 12.3 1.2 1.6 1.5 6.4 33. ... Tortrix viridana and 

 other leaf rollers 475.7 416.2 375.2 545.9 220.9 184.9 121.3 123.7 98.9 78.6 84.0 

123.9 

36. Wood-eating insects 36.1 39.8 48.4 50.0 33.7 19.3 34.8 58.2 278.6 191.7 201.7 183.4 37. Melolontha and other  chafers 107.7 106.9 105.7 107.5 101.5 99.9 93.4 83.4 77.5 76.2 79.0 

76.3 

38. Aradus cinnamomeus 20.6 19.3 19.7 17.2 16.8 15.5 12.7 10.2 9.7 9.0 7.7 5.5 39. Rodents 5.3 3.2 2.2 3.7 5.5 59.6 3.5 2.7 5.7 3.4 2.5 2.4 41. Diseases, including 79.2 163.4 207.8 239.1 1467.0 273.6 943.5 808.7 852.8 954.1 966.3 1081.1 42. ... root rot 44.0 49.7 72.0 87.9 99.4 115.1 136.1 136.7 134.8 138.9 145.4 160.8 

*All data in the Form No. 12 must be given in ha, here they are presented in thousands ha to be more convenient for consideration 
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 63

breakage” which is the consequence of the impact it would be more correctly to say “the impact of

wind and snow”; line 20 includes data about needle-eating pests, and line 30 includes data about leafeating insects. The sum of columns attributed to certain pest species can be less than the figures

provided in lines 20 and 30, because the total areas can include damage by other species that are not

listed; the instructions allows us to add new lines with data about the foci of pests that are important

in certain years for certain regions, for example, the data provided for Boarmia bistortata.

Line 41 contains data about forest diseases in addition to the root rot mentioned in line 42: these

include Armillaria mellea root rot, the canker (pathogen Peridermium pini), the Dutch elm disease

(pathogen Ceratocystis ulmi), the oak wilt (pathogen C. roboris) which affect predominantly adults

stands of various species, the pine shoot rust (pathogen Melampsora pinitorqua), disease of pine

underwood and young plants in nurseries and plantations.

If stands, forest plantations, and nurseries are infected by several species of pests or diseases, it is

recommended to mention the area infected by the dominant species.

Another supplementary form, Form No. 22 for forest-pathology information and accounting is

prepared in November for forest management administration. It is then used for planning forest

protection activities for the coming year. This form presents information about the area of foci at the

beginning of the year, the area that is newly infested, the area of foci that was abolished including

that which was eliminated by natural factors, the area of foci at the end of year, and what portion of

it “needs to be treated”. However, these kinds of data are not adequate for use for scientific purposes.

Table 2 presents data transformed from Table 1 followed by the contribution (in percent) of each

group of factors that cause the death of forests. These data suggest that forest fire is the most

dominating factor and that their impact is catastrophic: 51 to 91% of forests were killed between

1990—2001; the proportion killed by fire was less than 50% only in 1995 and 2001.

The contribution of insects in the death of forests seems to be insignificant as compared to fire and

caused less than 10% mortality during the period of this report. The exception occurred in 1995-

1996 after an outbreak of Dendrolimus sibiricus in Siberia, which caused 38-48% mortality of trees. It

is likely that in current and succeeding years, the area of forests killed may increase significantly as a

result of recent outbreaks of D. sibiricus and other needle-eating insects in the Asian part of Russia.

Table 2.—Areas of Russian forests killed by groups of factors (103

 ha / percentage)

Year Factors of unfavorable impact

insects wild animals diseases weather Fires anthrop.

1990 2.4 / 1.5 13.3 / 8.4 0.7 / 0.4 45.0 / 28.4 95.4 / 60.2 1.6 / 1.0

1991 8.9 / 2.1 9.2 / 2.2 1.9 / 0.4 184.7/ 44.0 213.4 / 50.9 1.2 / 0.3

1992 19.2 / 3.9 9.3 / 1.9 1.4 / 0.3 86.9 / 17.7 313.1 / 63.6 62.2 / 12.6

1993 13.2 / 7.7 3.9 / 2.3 0.8 / 0.5 19.6 / 11.4 131.6 / 76.9 2.2 / 1.3

1994 25.4 / 9.3 5.3 /1.9 1.1 / 0.4 15.9 / 5.8 225.3 / 82.1 1.4 / 0.5

1995 78.4 / 48.3 4.5 / 2.8 1.9 / 1.2 22.9 / 14.1 53.1 / 32.8 1.5 / 0.9

1996 194.5 / 37.8 1.0 / 0.2 3.5 / 0.7 24.2 / 4.7 291.0 / 56.5 0,8 / 0,2

1997 3.0 / 1.2 1.5 / 0.6 2.2 / 0.9 18.6 / 7.3 227.8 / 89.6 1.1 / 0.4

1998 3.1 / 1.1 1.1 / 0.4 5.1 / 1.8 15.3 / 5.5 245.9 / 88.1 8.7 / 3.1

1999 3.6 / 1.2 0.2 / 0.1 6.0 / 2.0 20.1 / 6.7 268.4 / 89.6 1.2 / 0.4

2000 20.3 / 2.9 1.2 / 0.2 5.5 / 0.8 33.6 / 4.8 637.4 / 91.1 1.9 / 0.3

2001 15.5 / 3.2 0.7 / 0.1 11.3 / 2.3 11.0 / 2.3 127.1 / 26.1 161.4 / 33.2
64 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

These two forms, No. 12 and No. 22, are prepared for forests of all subjects of the RF and separately

for certain especially preserved territories. The territory of Russian forests are divided into 12 regions

(Lesnoi Fond Rossii, 1999): Pribaltiiskii (the Baltic region), Severnyi (the Northern region), SeveroZapadnyi (the North-Western region), Tsentral’nyi (the Central region), Volgo-Vyatskii (the VolgaVyatka interfluve region), Tsentral’no-Chernozyomnyi (the Central Black Soil region), Povolzhskii

(the Volga region), Severo-Kavkazskii (the Northern Caucasus region), Uralskii (the Ural region),

Zapadno-Sibirskii (the Western Siberia region), Vostochno-Sibirskii (the Eastern Siberia region), and

Dal’nevostochnyi (the Far East region). The classification of separate subjects of the RF to these

regions is made in the above-mentioned reference rather conventionally, but it insight about the

distribution of certain disturbances within different regions of Russian forests.

Dynamics of foci of insect defoliators

Table 1 presents data about areas of outbreak foci of the most important needle- and leaf-eating

insects included in the form of compulsory statistical accounts. The remaining tables provide

information about the distribution of foci of defoliators by regions. Only data for infested areas

exceeding 100 ha are included.

Table 3.—Dynamics of foci of Dendrolimus sibiricus by region,

103

 ha

Year Regions

Ural West Siberia East Siberia Far East

1990 0.0 2.6 0.8 0.8

1991 0.9 27.1 45.4 11.2

1992 0.9 76.8 62.0 1.2

1993 0.0 6.8 5.4 0.0

1994 0.0 13.7 131.4 0.0

1995 0.0 5.1 569.7 0.0

1996 0.0 7.7 107.3 130.6

1997 0.0 10.8 70.0 0.9

1998 0.0 34.6 85.8 0.4

1999 0.0 54.3 76.2 21.7

2000 0.7 238.6 77.7 5940.7

Table 4.—Dynamics of foci of Dendrolimus pini by region, 103 ha

Year Regions

Black Soils Volga Northern Caucasus Ural West Siberia East Siberia

1990 0.0 0.1 1.1 4.0 0 0.0

1991 9.0 0.1 2.8 0.1 0 0.0

1992 2.9 0.1 3.9 0.1 0 0.0

1993 3.1 0.1 3.0 0.1 0 0.0

1994 2.4 3.7 5.2 0.1 0 0.0

1995 0.2 3.5 7.2 0.1 0 0.0

1996 1.8 1.3 5.2 0.1 0 0.0

1997 0.6 0.6 8.9 0.0 0 0.0

1998 1.2 0.5 6.8 1.1 0 0.0

1999 1.1 0.2 3.8 1.3 0 3.0

2000 0.8 0.2 0.9 1.3 18.7 2.0
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 65

Table 5.—Dynamics of foci of Bupalus piniarius by region, 103 ha

Year Regions

Northwestern Volga Northern Caucasus Ural West Siberia East Siberia

1990

1991 0 0 0.4 3.4 0.1 0

1992 0 0 0.4 4.8 0.1 0

1993 0 0.1 1.4 2.6 12.5 0

1994 0.2 0 1.4 2.6 16.3 0.4

1995 1.6 0 1.4 1.2 1.1 0

1996 2.2 1.8 1.4 24.0 0 0

1997 2.2 1.8 3.0 113.6 0 0

1998 2.2 1.8 2.2 3.6 3.0 0

1999 0.2 1.8 2.1 2.3 3.0 1.2

2000 0 1.8 3.3 3.8 3.0 0

2001 0 1.8 0.8 6.0 3.0 0

Table 6.—Dynamics of foci of Panolis flammea by region, 103 ha

Year Regions

Centr. Black Soil Volga Northern Caucasus Ural

1990 0.0 0.0 0.0 0.0 0.4

1991 0.0 0.0 0.0 0.0 0.4

1992 0.0 0.0 0.0 0.0 0.4

1993 0.0 0.0 0.0 0.0 0.3

1994 0.0 0.0 0.0 0.0 0.2

1995 0.4 0.0 0.0 0.0 0.2

1996 0.1 0.0 0.0 0.0 0.2

1997 0 0.0 0.0 3.2 0.1

1998 0.0 0.7 10.4 0.0

1999 1.3 0.7 1.1 0.0

2000 6.2 6.1 18.7 0.0

Table 7.—Dynamics of foci of Neodiprion sertifer by region, 103 ha

Year Regions

North Central Black-Soils Volga Volga-Vyatka Northern Caucasus Ural West Siberia

1990 0.0 1.7 10.1 15.8 2.0 9.1 8.3 59.9

1991 6.7 1.6 4.8 11.4 0.7 2.1 14.8 13.3

1992 5.5 0.0 1.4 13.4 0.0 6.7 10.5 3.1

1993 5.4 0.0 2.4 20.7 0.0 10.2 9.5 5.7

1994 0 0.0 4.1 12.2 0.0 7.6 3.5 8.3

1995 0.1 0.0 2.6 7.5 0.0 7.4 1.3 48.8

1996 0.1 0.0 2.4 16.2 0.0 9.3 0.8 0.7

1997 0.1 0.0 20.3 29.8 0.0 23.8 0.6 10.8

1998 0.0 0.0 11.6 24.8 0.0 12.8 1.9 5.3

1999 0.0 0.0 8.2 16.4 0.0 17.7 2.1 5.7

2000 0.0 0.0 6.9 13.3 0.0 8.9 6.5 3.9
66 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Table 8.—Dynamics of foci of Lymantria dispar by region, 103 ha

Year Regions

Baltic Central Volga Northern Caucasus Ural West Siberia East Siberia Far East

1990 0.0 0.0 40.9 248.2 12.2 0.0 9.9 0.0

1991 0.0 0.0 25.9 64.9 10.6 0.0 1205.6 0.0

1992 0.1 0.0 9.9 77.5 128.5 3.3 0.0 0.1

1993 0.6 0.0 3.7 100.1 77.0 13.4 0.0 0.2

1994 0.2 0.0 4.1 192.8 304.6 67.1 0.0 0.1

1995 1.6 0.0 5.3 180.8 295.7 122.9 0.4 0.0

1996 1.4 0.0 24.9 327.1 588.0 52.9 128.1 0.0

1997 0.2 48.8 22.6 283.0 80.5 197.8 322.4 0.0

1998 0.0 118.0 19.6 176.5 40.0 170.5 84.6 0.2

1999 0.0 63.7 0.3 165.2 94.5 172.9 0.0 0.2

2000 0.0 8.3 0.2 41.1 46.0 104.7 2.5 0.2

Forest pathology monitoring (FPM) in the Russian Federation

In the document “The Concept of Forest Protection and the Basis for the Organizing Structure of

the Service for Forest Protection in the Russian Federation,” developed by Russian specialists in

entomology and phytopathology by order of the Russian Federal Service for Forest Management, it

was mentioned as early as 1993 that the structure, content, and reliability of official statistical data

about the condition of Russian forests both totally and by regions are inadequate for preparing

analytical reviews and forecasts, and consequently for providing opportunities for effective forest

management. Data on tree mortality in forests caused by pests and diseases were considered by

authors as the least reliable. The situation will be improved only by implementing the specialized

system for assimilating data on FPM that has been developed by workers from the Russian Center on

Forest Protection in recent years. Since the beginning, this process requires a more detailed

interpretation of data on the influence of pests, diseases and other FUI on the condition and death of

forests from the statistical accountings.

The system of FPM in Russia has developed rapidly in recent years. The Statement on FPM in

Russian forests (1997) proclaims as its goal the development of a system for an operative and

permanent survey on the condition of forests, disturbance of their stability caused by pest organisms

and other natural and anthropogenic factors over time, so that timely information can be provided

about the condition of stands and the need for planning and applying forest protective measures.

The National Center for the forest pathology monitoring established in 1990 by the All-Union

Scientific Center for Forest Resources, issued regular reports on the sanitary condition of Russian

forests in 1991, 1992, and 1993. In 1994 the report was issued by the Moscow specialized enterprise

for forest pathology. After a brief interruption caused by the re-organization of the Service on Forest

Protection, the reports of the sanitary condition of Russian forests have been issued by the Russian

Center for Forest Protection in 1999—2001.

The Service of Forest Protection has recently received “Guidance for the Organization and Execution

of Forest Pathology Monitoring” (2002), which will promote further its development and

improvement.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 67

References Cited

Guidance for organization and execution of forest pathology monitoring in Russian forests. Ministry

for Natural Resources, the RF, Department for Utilization and Regeneration of the Forest Fund.

2000, 86 p. [in Russian]

The Protection of Environment. The statistical collection. M. Goskomstat. 1998. 202 p. [in Russian]

Review of the Sanitary State of Russian Forests in 1990, 1991, 1992. The National Center for Forest

Pathology Monitoring. M., 1990 (33p.), 1992 (41 p.), 1993 (62 p.) [in Russian]

Review of the Sanitary State of Russian Forests in 1993. Moscow Special Enterprise for Forest

Pathology Survey. M., 1994. 126 p. [in Russian]

Review of the Sanitary State of Russian Forests in 1998, 1999, 2000. The Russian Center for Forest

Protection. Pushkino: 1999 (33 p.), 2000 (34 p.), 2001 (46 p.) [in Russian]

The Sanitary Rules in Forests of the RF. (1998). The Forest Legislation of the Russian Federation.

M., 1999. P. 310-329. [in Russian]
68 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

North American budworms are eruptive insect species that form intimate ecological relationships

with their host trees. Population data for the eastern spruce budworm and jack pine budworm

implicate natural enemies as primary determinants of population collapses. Yet the dynamics of these

two species display markedly different temporal and spatial characteristics. One possible explanation

for these differences is variation in the strength of the density-dependent relationship between the

budworms and their host trees via the effects of defoliation on the adequacy of the host tree. The

proposed density-dependent relationship operates through the concept of risk of dispersal. In the jack

pine budworm, previous defoliation reduces subsequent production of pollen cones by the host tree.

These pollen cones are critical to survival of early stages of the jack pine budworm so that defoliation

has an immediate negative feedback on survival of future generations of budworm. In contrast, the

eastern spruce budworm is less reliant on pollen cones for early-season survival because of their

capability of mining old needles. However, defoliation over several years creates non-host gaps in the

forest and may also increase early-season mortality resulting from dispersal of small larvae. Thus hostplant relationships may be density-dependent sources of mortality in these life systems via their effect

on the risk of mortality resulting from dispersal. Variation in the strength of this density-dependent

interaction contributes to differences in the dynamical behavior of the different budworm species.

The eastern spruce budworm, Choristoneura fumiferana (Clemens), and the jack pine budworm, C.

pinus pinus Freeman, are eruptive species that periodically cause severe defoliation of their respective

host trees throughout northern conifer forests east of the Rocky Mountains in North America. These

species share a near-identical geographic range, life cycle and seasonal ecology. Eggs are laid in masses

on the needles of the host trees in mid-summer. Eclosion occurs within two weeks. Neonates do not

feed but settle in sheltered niches on the tree where they pass the winter. Larvae emerge in early

spring, typically before the current-year buds have flushed. This precocious emergence forces the

budworms to feed temporarily on alternative food sources. Both species readily utilize pollen cones

(male strobili) of the host tree which typically develop in advance of vegetative shoots. Eastern spruce

budworm may also mine old needles (McGugan 1954). Jack pine budworm, however, appears unable

to mine the needles of its host (Nealis 1995). In all cases, extensive movement may be associated with

this foraging and budworms are frequently observed ballooning on silken threads between trees at

this time of year (Sanders 1991). As current-year buds expand and flush, budworms web together the

needles, feed for the remainder of their larval period with relatively little further movement, and

pupate near these feeding sites. During these later feeding and pupal stages budworms are attacked by

a variety of natural enemies (Sanders 1991, Nealis 1991,1995).

Most losses to budworm populations occur during the early larval stages before they establish feeding

sites. This paper examines the ecological relationship between the host-plant and mortality of

budworms early in the season. The hypothesis presented is that defoliation of the host plant by high

population densities of budworms increases the risk of mortality to subsequent budworm generations

by increasing the likelihood of early-season dispersal and/or the relative rate of mortality that results

from this dispersal, i.e. by increasing the risk of dispersal. Thus, early-season dispersal losses can be

viewed as a lagged, density-dependent mortality factor in the budworm system. Variation in the

strength of the host-plant relationship and dispersal losses result in differences in the observed

dynamics of these budworms.

Host-plant Relationships and Comparative Ecology of Conifer-feeding

Budworms (Choristoneura spp.)

V.G. Nealis

Natural Resources Canada-Canadian Forest Service, Pacific Forestry Centre,

 506 W. Burnside Rd. Victoria, British Columbia, Canada, V8Z 1M5

 vnealis@pfc.forestry.ca
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 69

Population Dynamics

Royama (1984) concluded that the primary fluctuation in populations of the eastern spruce

budworm, the 35-year regular oscillation in density, is caused by lagged, density-dependent mortality

occurring in the late-larval and pupal stages. The most probable agents responsible for this mortality

are generalist predators, parasitoids, and possibly pathogens. This interpretation is consistent with

theoretical models which view cyclic population behavior as the result of lagged, numerical responses

of predators to changes in prey density (Royama 1992). Further support for this view comes from the

apparent lack of the effect of major host-trees, balsam fir (Abies balsamea) and spruces (Picea spp.), on

the primary fluctuation in eastern spruce budworm populations. When budworm kills all of the trees

in a stand, populations necessarily collapse. But populations also collapse in forests where mortality

of host trees is not complete (Royama 1984, Nealis and Régnière 2003). Experimental work by

Lawrence et al. (1997) showed that plant quality does play an important role in the ecological

relationship between the budworm and its host tree but it is a seasonal dynamic interaction not

clearly related to temporal patterns in the density of eastern spruce budworm populations.

Overall, then, eastern spruce budworm population dynamics are viewed as “top-down” with

regulation of populations imposed by “higher” trophic levels. Examples that illustrate these density

and mortality patterns from outbreaks in northern Ontario, Canada, in 1985 are provided in Fig. 1.

Continuing outbreaks such as Black Sturgeon Lake have little mortality caused by natural enemies

and their densities do not change greatly over the generation (Fig. 1a) whereas collapsing populations

such as observed at Gargantua display dramatic reductions in density associated with a sharp increase

in mortality from natural enemies at the end of the feeding period (Fig. 1b). A similar pattern of

increased parasitism in the late-larval stages during collapses of outbreaks of the jack pine budworm

was documented by Nealis (1991). Further, the same species of generalist natural enemies in the same

rank order of relative abundance were implicated in both the eastern spruce budworm and jack pine

budworm systems (Nealis 1991, 1995).

Despite their similar life cycle and ecology, the population dynamics of the eastern spruce budworm

and jack pine budworm differ in an important aspect. Whereas eastern spruce budworm populations

display long-term cyclicity with outbreaks synchronized over hundreds of thousands of ha (Royama

1984), jack pine budworm outbreaks are short-lived and more sporadic (McCullough 2000). Where

cyclical behavior in jack pine budworm populations has been detected, it is associated more with

abiotic conditions such as fire history, weather, and soils than with natural enemies (Volney and

McCullough 1994, McCullough 2000). Moreover, outbreaks of the jack pine budworm show no

particular synchrony with eastern spruce budworm outbreaks despite the fact that both species share

an identical guild of natural enemies and geographic sympatry.

Figure 1.—Changes in density of eastern spruce budworm (solid circles) and

mortality resulting from natural enemies (open circles) in a) a continuing

outbreak at Black Sturgeon Lake; and b) a collapsing outbreak at Gargantua,

Ontario, Canada in 1985.
70 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

An explanation for the the short-term nature of jack pine budworm outbreaks relative to those of the

eastern spruce budworm may lie in the obligatory relationship between the jack pine budworm and

the pollen cones of its host tree, jack pine (Pinus banksiana). The preference of early-stage jack pine

budworm to feed on pollen cones of its host tree was first recognized by Graham (1935). Jack pine is

a prolific producer of pollen cones under most forest conditions and outbreaks of jack pine budworm

often follow periods of particularly heavy pollen cone production in open stands of mature trees

(McCullough 2000, Nealis et al. 2003). Nealis and Lomic (1994) demonstrated that survival of earlyinstar jack pine budworm is related directly to the local abundance of pollen cones in a stand; when

pollen cones are sparse, mortality increases because budworms disperse from host trees and often fail

to find a suitable feeding site.

Defoliation by high-density populations of the jack pine budworm, however, causes a dramatic

reduction in the propensity of the host tree to produce pollen cones the following year. Comparison

of pollen cone production of several thousand trees in a series of defoliated and non-defoliated sites

in Ontario, Canada, over a 7-year time series revealed that the probability of a jack pine tree

producing pollen cones was reduced by 85% in the year immediately following peak defoliation (Fig.

2). Thus as high-density populations of jack pine budworm cause severe defoliation, they reduce the

availability of the necessary resource for future generations. The greater the severity of the defoliation,

the greater the reduction in future propensity to produce pollen cones (Nealis et al. 2003). This sets

up a negative feedback with a lag in the system analogous to a predator/prey cycle except in this case

the jack pine budworm is the predator and the pollen cones serve as the prey.

The feedback between the effects of defoliation and subsequent survival is less evident in the eastern

spruce budworm system. First, although eastern spruce budworm is similar to jack pine budworm in

that it feeds preferentially on the pollen cones of its host (Blais 1952), it is far less reliant on these

structures since early stage larvae also readily mine old needles (McGugan 1954) and are adapted to

maximizing the nutritional value of this suboptimal food source (Trier and Mattson 1997).

There is, nonetheless, evidence of a density-related effect in the host-plant relationship that may

influence dynamics of the eastern spruce budworm. Figure 3 illustrates a time series of log survival of

early-stage eastern spruce budworm (log density of budworms in their first feeding site minus the log

density of eggs) from Black Sturgeon Lake, Ontario, Canada. The outbreak lasted 15 years and thus

provides us with an unusually long time series. Here, we see something quite different from the

pattern described by Royama (1984); survival in these early stages decreases steadily throughout the

time series. This trend is very gradual at first and would have been less convincing, or perhaps not

Figure 2.—Percentage of jack pine trees

producing pollen cones in non-defoliated

stands (open circles) and in stands

defoliated by the jack pine budworm

(closed circles). Histogram illustrates mean

percentage defoliation in defoliated stands

standardized by year of peak defoliation

(i.e. year of peak defoliation = 0). Data

derived from 180 sample plots in Ontario,

Canada. Modified from Nealis et al. (2003).
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 71

even apparent in the shorter time series that was available to Royama (1984). Note the abrupt

downturn in rate of survival after approximately 10 years of defoliation in Fig. 3.

An hypothesis to explain this trend is that increasing early-season losses in the eastern spruce

budworm are also the result of previous defoliation in the stand as was the case with the jack pine

budworm. In the eastern spruce budworm however, the effect of defoliation becomes a factor only

after repeated annual defoliation causes whole-tree mortality of host species with consequent

development of canopy gaps (Kneeshaw and Bergeron 1998). Even if the rate of dispersal does not

change, mortality resulting from this dispersal would increase because of the lower likelihood of

dispersing larvae landing on a suitable host plant. A relative increase in the loss of early-stage

budworm has been reported when stands are thinned for management purposes (Jennings et al.

1983). In the case of Black Sturgeon Lake (Fig. 3), significant tree mortality began around 1990 and

accelerated throughout the remainder of the outbreak (Nealis and Régnière 2003). Population

regulation thus occurs at a larger spatial scale with the eastern spruce budworm because it is through

large-scale changes in stand composition that dispersal losses are mediated, rather than through

small-scale changes in tree characteristics as occurs with the jack pine budworm.

Comparative dynamics

The interpretation of dynamics presented here is based on the concept of risk of dispersal. Risk of

dispersal is the product of the propensity of an early-stage larva to disperse or forage for a feeding site

and the likelihood of that movement resulting in mortality. It is density-dependent variation in the

risk of dispersal, variation that is both intrinsic to the specific insect-tree interaction as well as within

a system over time, that is key to this interpretation.

Most mortality in the life cycles of both eastern spruce and jack pine budworm occurs before the

insects establish feeding sites. Because these species emerge in the spring before current-year foliage of

their hosts is available, losses associated with foraging in an inadequate environment are common.

Both budworm species benefit from the presence of pollen cones as these structures are available early

in the season and therefore enhance survival of early larval stages. For jack pine budworm, the

importance of these pollen cones is critical since feeding on previous-season foliage is not an option

and the risk of mortality from dispersing in a relatively open forest situation is high. Thus, the

depression of pollen cone production resulting from previous defoliation is a strong, densitydependent effect that increases the propensity of jack pine budworm to move and thereby increases

its risk of dispersal. This results in a tight, fast-acting feedback between defoliation, or jack pine

budworm density, and survival in subsequent generations. Outbreaks are short-lived and tree

mortality is confined to suppressed and intermediate tree classes (McCullough 2000). Retention of

susceptible, dominant trees in the stand and recovery of pollen cone production to pre-defoliation

levels within a few years (Nealis et al. 2003) results in the potential for recurrence of outbreaks within

a relatively short time-frame.

Figure 3.—Annual log difference (k-value)

between density of eastern spruce

budworm at the egg and early-larval

stages throughout a prolonged outbreak at

Black Sturgeon Lake, Ontario, Canada. An

accurate estimate of egg density in 1993

is not available.
72 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Defoliation by the eastern spruce budworm also reduces pollen cone production in balsam fir (Ghent

1958). The effect of this reduction in availability of pollen cones on eastern spruce budworm

populations, however, is not apparent because of the capability of the budworm to mine needles as an

alternative food source (McGugan 1954). Moreover, defoliation actually induces production of

epicormic shoots in balsam fir and white spruce (Nealis and Régnière 2003) further buffering the

negative effects of defoliation on survival of subsequent budworm generations. Consequently the

negative feedback between herbivory-induced changes to the tree condition and survival of eastern

spruce budworm is very weak; in fact, it simply functions on a longer time scale. Unlike jack pine

budworm, where tree mortality tends to be restricted to suppressed trees, persistent defoliation by the

eastern spruce budworm usually results in at least some mortality of dominant trees and the

development of gaps within the stand (Kneeshaw and Bergeron 1998, Nealis and Régnière 2003).

Thus, even if the propensity for early-stage eastern spruce budworm to disperse does not change

greatly over the course of an outbreak, the likelihood of mortality resulting from that dispersal will

certainly increase as more of the landbase becomes occupied by non-hosts (Jennings et al. 1983).

Either way, the risk of dispersal increases slowly over time.

Conclusion

Theoretical population dynamics models tell us that when lagged, density-dependent processes

operate within a persistent system, cyclical population behaviour can be expected (Royama 1992). If

conifer-feeding budworm systems all have lagged, density-dependent host-plant relationships, are

these sufficient to explain the eruptive nature of their populations? Are natural enemies merely

following, not driving, population cycles?

A definitive answer to these questions will require a more comprehensive modelling of population

dynamics. This modelling will rely on obtaining better estimates of parameters relating the host-plant

interactions to changes in population densities and with sufficient estimates of the influence of

natural enemies. A useful working model should reconcile the existing weight of both theoretical and

empirical evidence associating population cycles with the action of natural enemies and the

emergence of new data and hypotheses gained from the comparative approach provided in this paper.

If the collapse of budworm populations is caused ultimately by a per capita increase in the rate of

mortality due to natural enemies and these same natural enemies are ubiquitous in forests inhabited

by both eastern spruce and jack pine budworms, then it is necessary to add another element that

explains why these different budworm species exhibit different dynamics in terms of the frequency

and duration of outbreaks. The evidence of the comparative approach is that differences in the

strength of the feedback between defoliation and changes in the host-tree that render the host less

suitable for early-stage budworm may be that missing element. This aspect of the insect-host

relationship requires more explicit inclusion in general models of budworm population dynamics.

Structurally, inclusion of the insect-host relationship would result in a model with at least two

density-dependent processes affecting budworm density at two distinct stages in the life cycle. The

first, the insect-plant feedback outlined here, varies systematically between systems as outlined in this

paper. The second density-dependent process, the impact of natural enemies, is stochastic in that

many other intractable factors, such as the relative abundance of alternative hosts for generalists

natural enemies, influence the numerical response of these natural enemies. The important concept

here is that the likelihood of natural enemies impacting significantly generation survival of the

budworm is conditioned by what happens earlier in the life stage; i.e. by the first density-dependent

process. This is because an increase in apparent mortality from generalist natural enemies can be

brought about by either a numerical increase in those natural enemies, or by a decrease in the

abundance of budworms entering the susceptible stages.

The need to include more explicitly the insect-host interactions in budworm population dynamics

has been recognized before, especially for the western spruce budworm and the jack pine budworm

(Campbell 1993). Process-oriented research, however, has focused on possible changes in the quality
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 73

of foliage following defoliation. One technical problem that exists is that it is not clear what

constitutes meaningful measures of quality or how these may be applied to interpretation of

population patterns. In contrast, measurement of quantitative or topographical changes in the hosttree at either the individual or stand level is straightforward. Combining these with sufficient

measures of budworm density at the critical stages (egg mass and early-feeding stages) should prove

revealing.

References Cited

Campbell, R.W. 1993. Population dynamics of the major North America needle-eating budworms.

USDA Forest Service, Research Paper PNW-RP-463. 222 pp.

Blais, J.R. 1952. The relationship of the spruce budworm (Choristoneura fumiferana Clem.) to the

flowering condition of balsam fir (Abies balsamea [L.] Mill.). Can. J. Zool. 30: 1-19.

Ghent, A.W. 1958. Mortality of overstory trembling aspen in relation to outbreaks of the forest tent

caterpillar and spruce budworm. Ecology 39: 222-232.

Graham, S.A. 1935. The spruce budworm on Michigan pine. Bull. No. 6, School of Forestry and

Conservation, University of Michigan, Ann Arbor.

Jennings, D.T., Houseweart, M.W. and J. B. Dimond. 1983. Dispersal losses of early-instar spruce

budworm (Lepidoptera: Tortricidae) larvae in strip and clearcut and dense spruce-fir forests of

Maine. Environ. Entomol. 12: 1787-1792.

Kneeshaw, D.D. and Y. Bergeron. 1998. Canopy gap characteristics and tree replacement in the

southeastern boreal forest. Ecology 79: 783-794.

Lawrence, R.K., Mattson, W.J. and R.A. Haack. 1997. White spruce and the spruce budworm:

defining the phenological window of susceptibility. Can. Entomol. 129: 291-318.

McCullough, D.G. 2000. A review of factors affecting the population dynamics of jack pine

budworm (Choristoneura pinus pinus Freeman). Popul. Ecol. 42: 243-256.

McGugan, B.M. 1954. Needle-mining habits and larval instars of the spruce budworm. Can.

Entomol. 86: 439-454.

Nealis, V. 1991. Parasitism in sustained and collapsing populations of the jack pine budworm,

Choristoneura pinus pinus Free. (Lepidoptera: Tortricidae), in Ontario, 1985-1987. Can.

Entomol.123: 1065-1075.

Nealis, V.G. 1995. Population biology of the jack pine budworm. In: Volney, W.J.A., Nealis, V.G.,

Howse, G.M., Westwood, A.R., McCullough, D.G. and B.L.Laishley (eds.). Jack Pine Budworm

Biology and Management. Nat. Res. Canada. Inf. Rep. NOR-X-342. Pp. 55-71.

Nealis, V.G. and P.V. Lomic. 1994. Host-plant influence on the population ecology of the jack pine

budworm, Choristoneura pinus (Lepidoptera: Tortricidae). Ecol. Entomol.19: 367-373.

Nealis, V.G. and J. Régnière. 2003. Insect-plant relationships influencing disturbance by the eastern

spruce budworm, Choristoneura fumiferana (Clem.) (submitted).

Nealis, V.G., Magnussen, S. and A.A. Hopkin. 2003. A lagged density-dependent relationship

between jack pine budworm Choristoneura pinus pinus and its host tree Pinus banksiana. Ecol.

Entomol. 28: 183-192.
74 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Royama, T. 1984. Population dynamics of the spruce budworm, Choristoneura fumiferana. Ecol.

Monog. 54: 429-462.

Royama, T. 1992. Analytical Population Dynamics. Chapman and Hall, London.

Sanders, C.J. 1991. Biology of North American spruce budworms. In L.P.S. van der Geest and

H.H. Evenhuis (eds.) Tortricid Pests, Their Biology, Natural Enemies and Control. Pp. 579-620.

Elsevier Science Publishers, Amsterdam.

Trier, T.M. and W.J. Mattson. 1997. Needle mining by the spruce budworm provides sustenance in

the midst of privation. Oikos 79: 241-246.

Volney, W.J.A. and D.G. McCullough. 1994. Jack pine budworm population behaviour in

northwestern Wisconsin. Can. J. For. Res. 24: 502-510.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 75

Abstract

A model describing development of the spruce bark beetle, Ips typographus, combines topo-climatic

aspects of the terrain with eco-physiological aspects of the bark beetle. By correlating air temperature

and solar irradiation measured at a reference station, along with topographic data and microclimatic

conditions of terrain plots, topo-climatic models of a given research area are established. Within the

scope of modeling, GIS is used for data processing and visualization. The model allows a monitoring,

retrospective analysis and prognosis of brood development at any site and thus facilitates decisionmaking in forest management and the identification of hazardous zones.

Introduction

Populations of Ips typographus, the most severe forest pest in Central Europe, have expanded and

intensified due to favorable climate change and more frequently occurring extreme weather

conditions, and may increase in severity in the future. The situation has been aggravated by the fact

that, after the Second World War, most of the forest stands in Central Europe were planted mainly

with spruce. The total area of such plantations in Austria alone amounts to 1 million hectares. These

stands are now approaching a critical age where they are attacked readily by the beetle, therefore an

abundance of appropriate brood material is available to support devastating outbreaks of this bark

beetle species. Control of Ips typographus is hindered by the fact that its outbreaks are not only

restricted to secondary planted spruce forests of lowlands. As evidenced in the National Park

“Bayerischer Wald” in Germany, where Ips infestations killed more than 75% of the spruce trees in an

area of about 3,500 ha, considerable damage may occur also in the highland at altitudes from 1100

to 1400 m (Bayerische Landesanstalt für Wald und Forstwirtschaft 1999).

Materials and Methods

We developed a model which provides forest organizations the capability to monitor and forecast

outbreaks of Ips typographus and which is comprised of the following components:

Aspects related to topo-climatology:

• topographic features such as elevation, slope, and aspect

• intensity of potential and effective solar irradiation

• temperature measurements of the air, phloem of trees (and soil)

• stand structural features such as tree species composition, canopy closure, etc.

Eco-physiological aspects of beetle development including:

• time of swarming and brood initiation

• thermal characteristics of developmental stages, i.e. effective thermal sums needed to complete

development of specific instars

• voltinism including the factors inducing and terminating diapause

These parameters constitute the input data-set of a database-management system. Information is

stored in the form of separate tables and the relationships needed for the model are analyzed and

validated by a linked statistical package via multiple regression analyses. Developmental modeling

allows us to assess times of brood initiation and actual stages of brood development at each single

Monitoring and Risk Assessment of the Spruce Bark Beetle,

Ips typographus

S. Netherer, J. Pennerstorfer, P. Baier, E. Führer and A. Schopf

Institute of Forest Entomology, Forest Pathology & Forest Protection, BOKU -

 University of Natural Resources and Applied Life Sciences, Vienna, Austria
76 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

point of the study terrain and for each time of the season. When combined with data concerning the

predisposition of forest stands to bark beetle attack, this model provides managers with a

comprehensive tool for risk assessment (Fig.1).

Requirement for the topo-climatic model include the following:

1. Installation of a base station (or reference station) to measure air temperature and solar

irradiation

2. Installation of gauging-stations to measure air temperature at various locations in the terrain

3. Deduction of the topographic parameters (elevation, exposure, and slope) from a digital

elevation model

4. Multivariate regression analysis of the data recorded at the base station, the gauging-stations,

and topographic parameters

By means of resulting correlations, “close to ground” air temperature can be extrapolated for any

location of the terrain (without the aspect of vegetation), based on data from the reference station.

A realistic estimation of bark beetle development requires the assessment of microclimatic conditions

for the bark beetle, i.e. calculation of mean daily phloem temperatures at various aspects of felled

trees and density conditions of the stand. Consequently, relations between phloem temperatures of a

spruce tree, air temperature and solar irradiation were deduced (comp. Pennerstorfer 2000) from data

at the gauging-stations that were established at an experimental site and by different indices of

canopy closure (Fig. 2).

Figure 1.—Components of a model to monitor bark beetle development and to assess the risk

of an outbreak.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 77

Results and Discussion

The terms resulting from the regression analyses allow us to extrapolate the phloem temperature of

trees from air temperature and solar irradiation measured at the reference station, and from indices of

canopy closure at the stand level. As expected, phloem temperature of the sun-exposed side of a tree is

much higher than the air temperature in an open stand, while in a closed stand, the exposure of the

log has no influence on cambial temperature (Fig. 3a-b).

Microclimatic conditions may differ significantly at short distances within a stand; this was shown by

recordings at forest sites in the High Tatras National Park (Tanap, Slovakia) in 2001 (Netherer et al.

2002). Beetles developing in a sun-exposed tree situated at the forest edge at an elevation of 1000 m

were able to complete two generations successfully, with offspring emerging up until August. Nearby

in a shaded tree, offspring reached only the larval stage of the second generation within the same

period of time.

Thus an estimation of the developmental progress of bark beetles within a tree must be related to

“effective phloem temperature sums,” which is the heat sum above the lower developmental threshold

needed for stage completion. The instar specific thresholds were determined in laboratory

experiments by using the “sandwich” technique (comp. Coeln et al. 1996, Wermelinger & Seifert

1998). Based on times and rates of larval development at different temperatures, lower threshold

values were derived for each stage by extrapolation and the corresponding thermal sum in day degrees

was calculated.

A realistic monitoring system for the development of Ips typographus requires further knowledge

about the following:

• Determination of voltinism, i.e. the proportion of uni-voltine and multi-voltine individuals

within a population

• number of sister broods and times of brood establishment by the parental beetles

• factors regulating induction and termination of diapause

• frost resistance of hibernating stages

• thermal thresholds that induce spring flight

Fig.2.—Experimental design for deducing the correlation of phloem temperature at various

positions on felled spruce trees and air temperature as well as solar irradiation (modified by

the degree of canopy closure).
78 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Figure 3a – b.—Phloem temperature

measured on felled logs in open (A)

and closed (B) stands.

The thermal values ascertained in the lab studies combined with the microclimatic conditions of

studied terrain allows us to evaluate and visualize the progress of a population’s development at any

time of the season and for any site within the research area. The mode of representation is variable

and may be realized in the form of tables, maps, or GIS supported 3-dimensional figures (Fig. 4).

The model may be implemented for various purposes which may include:

• Monitoring of insect development in general

• Modeling of scenarios to forecast insect development and to support decision-making regarding

modifications and adaptations of forest management in view of climate change

• Indicating the delineation of zones of risk in forest reservations and national parks.

• Retrospective analysis of population dynamics of insects that may provide new insights in

population ecology



open stand

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

0:002:004:006:008:00

10:0012:0014:0016:0018:0020:0022:00

time of day

temperature [°C]

0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00

400.00

solar irradiation [W/m2]



closed stand

0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

00:0002:0004:0006:0008:0010:0012:0014:0016:0018:0020:0022:00

temperature [°C]

0,00

50,00

100,00

150,00

200,00

250,00

300,00

350,00

400,00

solar irradiation [W/m2]

upside of the log east side of the log west side of the log

bottom of the log air temperature irradiation

Solar irradiation [W/m2

] Solar irradiation [W/m2

]

Temperature [°C] Temperature [°C]

Open stand

Closed stand

Time of day

A

B
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 79

References Cited

Bayerische Landesanstalt für Wald und Forstwirtschaft. 1999. Zur Waldentwicklung im

Nationalpark Bayerischer Wald 1999. Buchdrucker-Massenvermehrung und Totholzflächen im

Rachel-Lusen-Gebiet. http://www.lwf.uni-muenchen.de/veroef/veroef2000/baywa2000/index.htm

Coeln, M., Y. Niu, and E. Führer. 1996. Entwicklung von Borkenkäfern in Abhängigkeit von

thermischen Bedingungen verschiedener montaner Waldstufen (Coleoptera, Scolytidae).

Entomologia Generalis 21(1): 37-54.

Netherer S., J. Pennerstorfer, A. Schopf. 2002. Developmental modelling and a hazard-rating

system in order to assess long-term predisposition of sites and stands to infestations by Ips

typographus. “Tatry” final report individual partners report.

http://www.vsv.slu.se/schlyter/tatry/fin_rapp/FR43BOKU.htm

Pennerstorfer J. 2000. Forstentomologisches Monitoring im Quellschutzgebiet der Stadt Wien.

[Monitoring of bark beetle development in a spring protection area].

http://ifff.boku.ac.at/thermomod/

Wermelinger B, and M. Seifert. 1998. Analysis of temperature dependent development of the

spruce bark beetle Ips typographus (L.) (Col. Scol.). J. Appl. Ent. 122: 185-191.





Figure 4.—Data input and examples of outputs.
80 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

Characteristics such as the duration of the larval stage and attraction of larvae to oviposition by an

endoparasitic wasp were evaluated between groups of irradiated and non irradiated gypsy moth

larvae. Untreated larvae required a shorter time to reach the adult stage (both male and female). The

mortality of larvae was highest at the highest irradiation dose. Pupae that developed from larvae or

eggs irradiated at 110 Gy possessed a high degree of morphological abnormalities (93.18%) whereas

in the control group, only 3% were affected. Larval mortality caused by G. liparidis reached 17% in

the control group and 6 % in the irradiated treatment. The natural population density of gypsy moth

at the study plot was low during the experiment and corresponded to a period of latency. Of 750

larvae collected at all sites in 2001, 21.3% were killed by parasitoids and 54.4%. by pathogens and

unknown causes. There was a significant difference in the mortality of gypsy moth larvae between

selected treatments under field conditions. The parasitic fly Compsilura concinnata was the most

important parasitoid species present in the sites.

Key words: gypsy moth, Glyptapanteles liparidis, gamma radiation, larvae developmental time, SIT,

parasitoids.

Introduction

The use of the sterile insect technique for suppressing pest populations was proposed initially by

Knipling (1955). Since that time the effectiveness of using the sterile insect technique (SIT) has been

demonstrated by various models and has been applied operationally and successfully against many

insect species. This technique is based on overflooding the feral population with a large numbers of

sterile individuals (mostly males). When there is a high over flooding ratio of sterile: feral individuals

in the field, and the sterile individuals are fully competitive, the probability of mating of females by

fertile males declines. The sterile insect technique is well suited for population management of the

gypsy moth (Lymantria dispar L.) because it has one generation per year, and though males may mate

several times, females mate only once and produce an egg mass which may contain from 200-1600

eggs (Reardon and Mastro 1993).

Mastro and Schwalbe (1988) summarized various methods and strategies for using SIT against the

gypsy moth. Three different application techniques have been used: (1) deployment of totally sterile

male pupae; (2) deployment of male pupae treated with a substerilizing dose of radiation; and (3)

broadcasting F1 sterile eggs. Our objective was to evaluate a fourth method – the introduction of

larvae irradiated as eggs into the field to evaluate the effect of irradiation on larval behavior and to

determine if the introduction of larvae irradiated as eggs during the latency period would enhance the

activity of parasitoids and predators and thus facilitate biological control of the gypsy moth. Reardon

et al. (1987), reported that the release of F1 gypsy moth eggs in Maryland significantly increased

parasitism by Compsilura concinnata. It is suggested that SIT alone or in combination with low doses

of pesticides, could be used as an integrated approach to manage gypsy moth populations.

Material and Methods

For all laboratory experiments we used a laboratory strain (NJ) of the gypsy moth supplied by the

USDA – APHIS Methods Development Center in Otis, MA (U.S.A.). In the field tests, field

Sterile Insect Technique as a Tool for Increasing the Efficacy

of Gypsy Moth Biocontrol

Július Novotný and Milan Zúbrik

Forest Research Institute Zvolen, Research Station Banska Štiavnica, Lesnicka 11, 969 23

 Banská Štiavnica, Slovak Republic
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 81

collected gypsy moth egg were received through the cooperation of the Forest Research Institute

Bucharest, and Forest District Oradea, Romania.

Development of Irradiated and Non-irradiated Larvae

Gypsy moth eggs were irradiated at 10, 20, 30, 40, 50, 60, 80, or 110 Gy respectively a few days

before hatching and larvae were tested for differences in their development by comparison with nonirradiated controls (Gamacel 300 of the Entomology Unit of the IAEA ́s Seibersdorf Laboratory in

Seibersdorf, Austria was used).

Larvae were reared initially (5 per a cup) on an artificial diet (Bell et al. 1981); from the third instar,

larvae were reared separately and were checked daily. The duration of each larval stage was

determined by the time of molting. Dead larvae were removed from rearing cups and recorded.

Pupae that developed successfully were stored in boxes (60 cm x 60 cm x 100 cm high). The

condition and health of the pupae was determined two days after pupation at which time they were

weighed. The number of adults that emerged successfully was recorded.

Attraction of Sterile Gypsy Moth Larvae to Oviposition by the Endoparasitic Wasp

Glyptapanteles liparidis L.

Gypsy moth eggs were irradiated at 50 Gy using a source of cobalt radiation located at the Roosevelt

Hospital in the city of Banska Bystrica. The larvae were reared on artificial diet until they reached the

fourth larval stage.

We used laboratory strains of the endoparasitic wasp Glyptapanteles liparidis L., which was provided

by the Department of Entomology, Phytopathology and Forest Protection in the University BOKU

of Vienna (Austria).

To investigate the preference of G. liparidis, four replicates of 25 fourth instar larvae from irradiated

eggs and 25 non-irradiated fourth instars were placed in a rearing box along with five males and five

females of G. liparidis. The non-irradiated larvae were marked with dots of yellow paint; all larvae

were exposed for 24 hours. In order to create a more natural condition, a cage (50 x 50 x 75 cm,

covered with monofil) containing oak twigs and arborvitae branches was placed on a table in the lab.

The windows in the lab were darkened and artificial light was provided on all four sides. After the

period of exposure to the wasps, the larvae were removed and placed individually in 30 ml plastic

cup. Larvae were reared on artificial diet until parasitoids emerged, pupation occurred, or larvae died.

The Natural Enemy Complex of L. dispar on Experimental Plots

Field collected gypsy moth eggs were subjected to 25 Gy or 50 Gy respectively in early May, a few

days before hatching occurred. Three study plots were established in three young (10-15 years) oak

stands in the forest of Parovske Haje located near Nitra in southeast Slovakia; Quercus cerris and Q.

petraea were the main tree species. The distance of the study plots from each other was about 100 m.

Gypsy moth population density at the experimental sites was estimated by counting the number of

egg masses per tree in one plot located about 100 m from the study plots following the method of

Turcek (1956). Because of the low density of natural gypsy moth populations on the experimental

plots, we supplemented the populations so that an adequate number of larvae were available for

subsequent sampling. Therefore 600-1500 g of field collected, non irradiated, L. dispar eggs were

placed in the first site in the Spring and at the same time, an equal number of irradiated L. dispar

eggs were released in the second plot (25 Gy) and in the third plot (50 Gy). To determine levels of

parasitism, L. dispar larvae were collected from experimental plots at different stages of larval

development. We collected approximately 100 each of first and second instars (L1+L2), third and

fourth instars (L3+L4), and fifth and sixth instars (L5+L6) respectively. Early instars were collected

from twigs of the lower crown, stems of trees, understory vegetation, and litter. We used burlap bands

to collect late instar larvae.
82 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Field collected larvae were reared in groups of 20 or 30 larvae in glass cages on oak foliage under

room conditions (23 -25°C). Larvae were checked daily and dead larvae as well as larvae from which

parasitoids had emerged were removed. Adult parasitoids that emerged were identified and Tachinid

larvae that emerged were identified as pupae (Zubrik 1998). Giemsa stained smears were prepared

from dead larvae from which no parasitoid had emerged and viewed under light microscopy to

determine the presence of pathogens.

Data Analyses

Analyses of variance (ANOVA) was performed on larval duration and pupal weight to determine the

effects of irradiation dose (unequal number of replicates, Tukey HSD test) using SAS. The same

method was used in case of G. liparidis weight of cocoons and weight of male and female adults. We

used analyses of variance (ANOVA, equal number of replicates, LSD test) for evaluation the impact

of irradiation dose on the hatching ability of eggs (SAS). Significant differences were tested at

P<0.05.

Results and Discussion

Development of Irradiated and Non-irradiated Larvae

The duration of development of gypsy moth larvae subjected to doses of radiation (10-110 Gy) is

provided in Table 1. The duration of development of all larval instars subjected to irradiation differed

significantly from the controls. The control group developed 20 % faster than larvae exposed to the

110 Gy dose. Similar data were obtained by Mastro and Schwalbe (1988), who found that the

developmental time of F1 larvae from irradiated eggs varied from ca 30 days (20 Gy) to 34 days (100

Gy).

Differences in the condition of larvae and pupae were also recognized. Table 2 shows that the

mortality of larvae was highest when the higher irradiation doses were used. In the control group, the

mortality reached 5 % as compared to 20 % in the 60 Gy treatment. Pupae that developed from

irradiated eggs showed a high degree of morphological abnormalities (93.18% at 110 Gy) as

compared to 3% in the control group. The thoracic segments of the pupae were undeveloped and the

antennae were also abnormal. These abnormalities affected the emergence of adults, which was very

Table 1.—Mean development (mean ± SE) of L1-L5 gypsy moth larvae exposed as eggs to cobalt

irradiation and reared on artificial diet under laboratory condition.

Treatment Instar of larvae SUM

L1a L2 b L3 c L4 d L5 e

10 Gy eggs 10.70 ±1.31de 5.39 ± 1.13ab 5.38 ± 1.00d 4.58 ± 0.77e 8.42 ± 2.10b 34.49

20 Gy eggs 10.68 ± 1.18de 4.56 ± 1.00d 5.56 ± 0.58cd 5.36 ± 0.81c 6.44 ± 2.08b 32.60

30 Gy eggs 10.89 ± 1.09cd 5.24 ± 1.51abc 6.18 ± 1.46ab 4.89 ± 0.89dd 8.36 ± 2.21b 35.58

40 Gy eggs 11.08 ± 0.98c 5.28 ± 1.55abc 5.85 ± 1.14bc 5.22 ± 0.71c 8.36 ± 2.17b 35.80

50 Gy eggs 10.55 ±0.58e 5.32 ± 0.60abc 4.82 ± 0.65e 6.75 ± 1.31a 9.43 ± 3.12a 36.87

60 Gy eggs 11.50 ± 0.56b 5.52 ± 1.26ab 5.93 ± 1.01bc 5.85 ± 1.25b 8.87 ± 3.16a 37.68

80 Gy eggs 11.42 ±0.57b 5.10 ± 0.41bc 6.54 ± 1.24a 6.16 ± 1.00b 9.55 ± 4.05a 38.77

110 Gy eggs 12.24 ±0.91a 5.56 ± 0.57a 6.42 ± 0.70a 5.52 ± 0.81c 9.59 ± 4.26a 39.33

Control 2002 9.45 ± 0.84f 4.95 ± 1.06cd 5.69 ± 0.93cd 4.43 ± 0.74e 8.27 ± 2.48b 32.80

Means followed by different letters (within a columns) are significantly different at P ≤0.05 by Tukey HSD. a F =

49.08; df = 8. 723; P ≤ 0.01; b F = 5.95; df = 8. 716; P ≤ 0.01; c F = 14.53; df = 8. 697; P ≤ 0.01; d F = 42.85; df = 8.

679; P ≤ 0.01; e F = 3.32; df = 8. 668; P = 0.010.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 83

low in all treated groups. In the control group these symptoms were not recognized. Somatic

abnormalities are relatively common in the production of F1 larvae (Reardon et al. 1987).

We also evaluated how irradiation dose influenced the hatching of eggs. In the control group, the

number of unhatched eggs was 9.66% whereas the number of unhatched eggs varied from 28.89-

71.93% at doses over 60 Gy. This is quite important if irradiated eggs or larvae are destined for use

in field augmentation (Table 3).

Attraction of Sterile Gypsy Moth Larvae for Oviposition by the Endoparasitic Wasp

Glyptapanteles liparidis L.

Larval mortality caused by G. liparidis was 17% (17 of 100) in the control group as compared to 6%

(6 of 100) in the irradiated groups. There was recognized differences between the total number of

larvae killed by pathogens in the irradiated group as compared to the control group (48% vs. 10%).

Table 3.—Impact of irradiation dose on the hatching ability of eggs (N= number of egg masses).

Treatments N Average no. of eggs No. of unhatched % of unhatched eggs

X ±S.D. eggs X ±S.D. X ±S.D.

10 Gy eggs 10 363.9 ± 87.2 41.6 ± 9.9 11.43 ± 0.52a

20 Gy eggs 10 416.6 ± 118.0 51.8 ± 15.5 12.39 ± 0.42ab

30 Gy eggs 10 436. 3 ± 88.7 61.6 ± 12.1 14.14 ± 0.56bc

40 Gy eggs 10 396.6 ± 91.1 61.8 ± 15.1 15.53 ± 0.62c

50 Gy eggs - - - -

60 Gy eggs 10 411.8 ± 134.5 116.0 ± 35.6 29.18 ± 2.58d

80 Gy eggs 10 520.8 ± 159.5 249.5 ± 71.1 48.47 ± 4.36e

110 Gy eggs 10 452.1 ± 105.3 325.2 ± 66.8 72.31 ±11.41f

Control 10 412.8 ± 110.7 39.9 ± 13.2 9.58 ± 1.47a

Statistical differences - - - SD 

Means followed by different letters (within a columns) are significantly different at P ≤ 0.05 by LSD. SD=

significantly different at P ≤ 0.05 by LSD. F = 839.94; df = 7. 72; P ≤ 0.01

Table 2.—Mortality of larvae, condition, and weight of pupae from irradiated and control groups of L. dispar

fed on artificial diet in laboratory conditions (N= total No. of larvae per treatment).

 Treatment N Larval No. of Deformed Unhatched Weight of pupae (g)

mortality pupae pupae pupae

No % No. % No % Male a Female b

10 Gy eggs 100 4 4.0 96 8 8.33 18 18.75 0.5739 ± 0.045a 1.6622 ± 0.163a

20 Gy eggs 100 7 7.0 93 21 22.58 26 27.95 0.4708 ± 0.088b 1.4133 ± 0.218bc

30 Gy eggs 100 12 12.0 88 20 22.72 28 31.81 0.4738 ± 0.072b 1.3571 ± 0.147c

40 Gy eggs 100 16 16.0 84 22 26.19 38 45.23 0.4631 ± 0.031b 1.2400 ± 0.110d

50 Gy eggs 50 6 12 44 8 18,18 12 27.27 0.5726 ± 0.102a 1.5149 ± 0.164b

60 Gy eggs 100 20 20.0 80 29 36.25 53 66.25 0.4605 ± 0.054b 1.2190 ± 0.181d

80 Gy eggs 50 4 8 46 24 52.17 36 78.26 0.4407 ± 0.066b 1.0568 ± 0.277e

110 Gy eggs 50 6 12 44 41 93.18 39 88.63 0.3631 ± 0.038c 0.8984 ± 0.113f

Control 2002 100 5 5.0 95 3 3.15 7 7.36 0.5574 ± 0.030a 1.8625 ± 0.940b

Means followed by different letters (within a columns) are significantly different at P ≤ 0.05 by Tukey HSD. a F = 45.83;

df = 8. 419; P ≤ 0.01; b

 F = 43.09; df = 8. 232; P ≤ 0.01
84 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Unfortunately, females of G. liparidis exhibited low activity in searching for host larvae and therefore

the parasitism rate was lower than expected (Table 4). We also conclude that the high mortality

caused by pathogens in the irradiated group probably was responsible for the low rate of parasitism in

that group. Larvae killed by pathogens died before parasitoids were able to complete their

development.

There were no statistically significant differences between irradiated and control groups in the

development of G. liparidis larvae and duration of the cocoon and adult stages (Fig. 1).

We observed some differences in the characteristics of cocoons and adults of G. liparidis that

developed from irradiated and non-irradiated larvae. The numbers of fresh cocoons and total

cocoons produced from the non-irradiated (control) groups of larvae was higher than the numbers

produced from irradiated larvae. The mortality of cocoons was quite similar in both treatments.

Cocoons from non-irradiated larvae produced hatched larger adults, but these differences were not

statistically significant (Table 5).

Host selection experiments can be influenced by other factors, (Hoch et al. 1999). Consequently we

conducted additional tests to investigate the effect of microsporidian infection in the host on

parasitoid performance.

Natural Enemy Complex of L. dispar in Field Experimental Plots

The population density of L. dispar in the study plot was low during the experiment, which

corresponds to the early progradation period of the pest. Of 750 larvae collected at all sites in 2001,

Figure 1.—Mean developmental time (means ± S.D.) of parasitoid larvae within the

host, duration of cocoons, and duration of adult G. liparidis

0

2

4

6

8

10

12

14

16

18

20

Development of parasitoid 

larvae within the host

Duration of cocoons Duration of adults

Day

50 Gy

Control

Table 4.—Mortality induced by parasitoids, pathogens and total mortality in each treatment of

eggs irradiated at 50 Gy.

Replication 50 Gy Control

Pathogen Parasitoids Together Pathogen Parasitoids Together

No. % No % No % No. % No % No %

1 12 48.0 2 8.0 14 56.0 2 8.0 4 16.0 6 24.0

2 10 40.0 3 12.0 13 52.0 3 12.0 6 24.0 9 36.0

3 9 36.0 0 0.0 9 36.0 0 0.0 4 16.0 4 16.0

4 17 68.0 1 4.0 18 72.0 5 20.0 3 12.0 8 32.0

Σ 48 48.0 6 6.0 54 54.0 10 10.0 17 17.0 27 27.0
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 85

21.3% (160 of 750) were killed by parasitoids; the larval mortality caused by pathogens and

unknown causes was 54.4% (408 of 750).

The irradiated larvae showed a very high sensitivity to the field conditions that resulted in very high

mortality. Pathogens and unknown agents caused high mortality of the youngest larvae (L1+L2) and

almost 100 % mortality in older larvae (L3-L5). Mortality caused by pathogens and unknown causes

was much less among the control larvae (Table 6).

Parasitoids were very important as mortality agents in all experimental groups. We identified nine

species of parasitoids belonging to the families Braconidae and Tachinidae. The parasitic fly

Compsilura concinnata was the most prevalent parasitoid species. C. concinnata parasitizes mostly L3-

L4 instars. We did not determine significant differences among species nor between the rate of

parasitism between irradiated and non-irradiated larvae. The rate of parasitism was extremely similar

in medium age larvae and varied from 21.7% to 26.7%. We recognized the highest diversity of

parasitoids (nine species) in the control group of older larvae (L5+L6).

Table 6.—Causes of mortality (pathogens, parasitoids and unknown) in irradiated and nonirradiated gypsy moth larvae.

Cause of mortality Irradiated (25 Gy + Control Irradiated and control Rank

 50 Gy) together

No. % No. % No. %

of larvae of larvae of larvae

G. liparidis 5 1.0 1 0.4 6 0.8 4

C. melanoscela 10 2.0 5 1.6 15 2.0 3

G. porthetriae 6 1.2 2 0.8 8 1.0 5

Meteorus sp. 1 0.4 1 0.1

Compsilura concinnata 16 3.2 16 6.1 32 4.2 2

Drino incospicua 1 0.2 1 0.4 2 0.2

Blepharipa pratensis 1 0.2 1 0.4 2 0.2

Carcelia gnava 1 0.2 1 0.1

Zenilia libatrix 1 0.4 1 0.1

Ichneumonidae 63 12.8 29 11.1 92 12.2 1

Total parasitoids 103 21.0 57 21.9 160 21.3

Path + unknown 322 65.7 86 33.1 408 54.4

Total larvae 490 100 260 100 750 100

Table 5.—G. liparidis - weight of cocoons, number and weight of male and female adults, and mortality

of the cocoons for each treatment separately. Significant at P<0.05

Weight of No. of No of adults Adult Weight(g) Mortality during

the fresh cocoons the cocoon stage

cocoons (g) X Total M F M F (%)

50 Gy 0.002600 29.17 175 130 14 0.000292 0.000371 17.71

Control 0.002940 33.81 541 388 63 0.000294 0.000376 16.63

Statistical differences NS NS - - - NS NS -

NS= not significantly different at P ≤ 0.05 by Tukey HSD.
86 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Acknowledgments

This study was supported by IAEA (grant 10849). We thank Dr. A. Robinson (Entomology Unit,

Seibersdorf, Austria) and Dr. A. Rakytska (Roosevelt Hospital, B. Bystrica, Slovakia) for allowing us

to use their irradiation source and Mr. Ilkanič for technical assistance. We also thank Dr. M.

McManus for his assistance in the English language and useful comments.

References Cited

Bell, R. A., Owens, C. D., Shapiro, M., and Tardif, J. R. 1981. Development of mass rearing

technology. In: Doane, C. C. and McManus, M. L. (Eds.): The Gypsy Moth: Research Toward

Integrated Pest Management. U.S. Dep. Agr. Tech. Bull. 1584. 599-633.

Hoch G., Schopf, A., Maddox, J.V. 2000. Interaction between an entomopathogenic

Microsporidium and the endoparasitoid Glyptapanteles liparidis within their host, the gyspy moth

larva. J. of Invert. Pathol. 75: 59-68.

Knipling, E. F. 1955. Possibilities of insect control or eradication through the use of sexually sterile

males. J. Econ. Entomol. 48: 459 – 462.

Mastro, V. C., Schwalbe, C. P. 1988. Modern insect control: nuclear techniques and biotechnology.

In: Proceedings of an international symposium on modern insect control, IAEA, Vienna, p. 15-40

Reardon, R. C., Mastro, V. C. 1993. Development and status of the sterile insect technique for

managing gypsy moth. USDA, NA-TP-13-93. 17 p.

Reardon, R. C., McManus, M., Kolodny-Hirsch, D., Tichenor, R., Raupp, M., Schwalbe, C.,

Webb, R., Meckley, P. 1987. Development and implementation of a gypsy moth integrated pest

management program. J. Arbor. 13: 209-216.

Turcek, J. F. 1956. Mniska velkohlava. SVPL, Bratislava. 57pp.

Zúbrik, M. 1998. Contribution to the morphology of pupae of Tachinid (Diptera: Tachinidae)

parasites of gypsy moth Lymantria dispar (Lepidoptera: Lymantriidae) in Slovakia [Ger. ]. Forestry

Journal. 44 (4): 275-285.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 87

Abstract

During field evaluations of pheromone blends used for monitoring Tomicus piniperda beetles, many

non-target beetles were captured and identified. Five pheromone blends, plus commercially available

TOMODOR were used in two different traps: the IPM Tech Intercept PTBB and the THEYSOHN

intercept barrier trap. In addition to Tomicus bark beetles we trapped 3,469 other Coleoptera in three

of the 10 replications that represented 53 species distributed among 27 families. Most numerous

were representatives of Staphyllinidae, Elateridae, Cleridae and Rhizophagidae. Temporal distribution

of the most important predatory species as well as their responsiveness to pheromone blends is

presented. The results are discussed in terms of interspecies chemical communication and few

practical aspects relevant for the potential use in Tomicus monitoring or suppression activities.

Introduction

Recent developments in research on Tomicus piniperda pheromone communication (Csokajlo 1998,

Kolk 2000) and small scale outbreaks of this pest in some parts of Croatia, served as a basis for a

three-country (USA, Poland, Croatia) collaborative field test of new trap designs and pheromone

blends. In Croatia, a mixed Pinus sylvestris and P. nigra forest culture of 16 ha was chosen in the

continental part of the country (44o 44’ N, 15o 39’ E of Greenich). During the last three years a

heavy attack of several bark beetle species occurred in this area. The most important pests were: T.

piniperda, T. minor, Ips sexdentatus and I. acuminatus.

The research was initiated in 2001 but due to a late deployment of traps, the number of beetles

(target as well as non target) recovered was too low for us to make reasonable comparisons; the data

presented were recorded in 2002.

Materials and Methods

Six candidate semiochemicals, with or without the addition of ETOH, were tested in a completely

randomized block design with 10 repetitions. Each block consisted of 6 IPM Tech Intercept PTBB

traps and one THEYSOHN type intercept barrier trap equipped with odour blends with the

following characteristics and combinations:

Semiochemicals

α-pinene (AP), nonanal (N), (-)-trans-verbenol (TV), (-)-myrtenol (MOL), (-)-myrtenal (MAL),

(±)- α-pinene oxide (APOX), Ethanol (ETOH) and TOMODOR released at rates of 300, 6.0,

5.0, 5.0, 5.0, 2.5, and 20 mg/24 h at 24 o

C, respectively (release rate and blend of TOMODOR

was not known).

Blends

1. Blend #1 (AP) with IPM Tech Intercept PTBB

2. Blend #2 (AP + N + TV + MOL) with IPM Tech Intercept PTBB

3. Blend #3 (AP + N + TV + MOL + MAL) with IPM Tech Intercept PTBB

4. Blend #4 (AP + N + TV + MOL + MAL + APOX) with IPM Tech Intercept PTBB

5. Blend #4 (AP + N + TV + MOL + MAL + APOX) with THEYSOHN trap

6. Blend #5 (AP + N + TV + MOL + MAL + APOX + ETOH) with IPM Tech Intercept PTBB

7. Tomodor with IPM Tech Intercept PTBB

Beetle Fauna Captured in Traps Baited with Tomicus piniperda

Pheromone Blends in a Pine Stand in Central Croatia

Milan Pernek1, Boris Hrašovec2 and Miljenko Županič1

1

Forest Research Institute, Jastrebarsko, Croatia

2

Faculty of Forestry, University of Zagreb, Croatia
88 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Traps were positioned in each block 15 meters apart and close to the ground so both THEYSOHN

and IPM Tech Intercept PTBB collecting cups were about 20 cm above ground. Trapped beetles were

collected weekly or biweekly (later in the season), dried in the laboratory and identified.

Results

During the trapping period in 2002 (February – June), a total of 34,735 Tomicus beetles were

trapped: 33,488 T. piniperda and 1,241 T. minor. These numbers refer to a total number of 60 IPM

Tech Intercept PTBB traps and 10 THEYSOHN traps set up in the field trial. Blends #4 and #5

performed best based upon response by T. piniperda and the IPM Tech Intercept PTBB trap

outperformed by far the THEYSOHN trap in the capture of Tomicus and the predatory beetles.

(Figs. 1-3). An obvious time lag between the maximum flight period of the Tomicus and Thanasimus

offers the possibility to reduce the predatory catches by removing the traps (attractants) after the

initial flight of pine shoot beetles. Gradual decline of the Thanasimus catches later in the season

might be related to the appearance and boring activity of other bark beetle populations in the area (I.

sexdentatus, I. acuminatus)). It is unclear whether the clerid beetles could differentiate between their

scolytid prey on the basis of some specific compounds released during the initial phase of bark beetle

attack.

Non-target beetles that responded to the offered compounds belong to several guilds of wood

inhabiting insects, whether as xylophages, saproxyllic or predators. The most common were:

Paromalus parallelepipedus, Necrophorus humator, N. vespilloides, Agathidium sp., Anisotoma sp.,

Liodopria sp., Scaphisoma sp., Melolontha melolontha, Aphodius sp., Athous sp., Ampedus ferrugineus,

Melanotus sp., Megatoma undata, Thanasimus formicarius, Pityophagus ferrugineus, Ipidia

quadrimaculata, Rhizophagus ferrugineus, R. depresus, Uleiota planata, Cerylon evanescens, Lathridius

sp., Corticarina sp., Corticaria sp., Enicmus sp., Ditoma crenata, Mycetophagus quadripustulatus, Ptinus

sp., Vincenzellus ruficollis, Acanthocinus aedilis, Asemum striatum, Rhagium inquisitor, Anastrangalia

sanguinolenta, Cortodera sp., Pogonocherus sp., Anthribus albinus, Rhyncolus sp., Hylobius abietis,

Pissodes nottatus, Hylastes sp., Hylurgus ligniperda, Hylastes cunicularius, Xyloterus lineatus, Ips

sexdentatus, Orthotomicus sp.

Different responses of four non-target beetles depicted in Figure 4 may illustrate various colonizing

strategies regarding the state and physical condition of the attacked pine trees (reflected by different

amounts of chemical compounds released in time).

Figure 1.—Response of T. piniperda to offered blends. Figure 2.—Response of T. minor to offered blends.



















	






 


  






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No. beetles captured

No. beetles captured
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 89

Figure 3.—T. formicarius response on tested blends

and comparison with the total Tomicus catches (left

axis Thanasimus, right axis Tomicus beetles.

Figure 4.—Different response types for four nontarget species: T. formicarius, R. depressus, I.

quadrimaculata and P. parallelepipedus.

References Cited

Czokajlo, D. 1998. Semiochemicals for the Larger Pine Shoot Beetle (Tomicus piniperda L.) and its

Clerid Predators. Dissertation, State University of New York, College of Environmental Science

and Forestry, Syracuse, New York, 165 pp.

Kolk, A. 2000. Feromony i kairomony wybranych owadów fitofagicznych sosny pospolitej (Pinus

sylvestris L.) oraz możliwości ich wykorzystania w ochronie lasu. Instytut Badawczy Leśnictwa,

Warszawa, 129 pp.

Puchegger, F. 1987. Entwicklung einer Zuchttechnik für den Ameisenbundkäfer Thanasimus

formicarius. Diploma thesis, Institut für Forstschutz und Forstentomologie, Universität für

Bodenkultur, Wien.

Yüksel, B., G. Tozlu and M. Șentürk. 1999. The Serious Harmful Bark Beetles at Sar1kam1ș Scotch

Pine Forests and Their Precautions, Dogˇu Anadolu Ormanc1l1k Araș1trma Müdürlügˇü, Teknik

Bulten Yay1n1 No: 3, Erzurum, 71pp.



















	








 


  




















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No. beetles captured

% capture
90 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

Long-term monitoring followed by mathematical modelling was used to describe the population

dynamics of the green oak leaf roller Tortrix viridana L. over a period of 30 years and to study reactions of

oak stands to different levels of defoliation. The mathematical model allows us to forecast the population

dynamics of the green oak leaf roller and main characteristics of its development: survival, fecundity, and

propagation coefficient. The model demonstrated that oak stands in various sites differ in their response

to severe defoliation. The responses of absorbing roots of damaged trees are most intense after the first year

of damage and decrease gradually if subsequent defoliation occurs. The analysis of weather characteristics

over 50 years revealed that the hydro-thermic coefficient of growing seasons increased 1.7 times

during the last 30 years; this may be favorable for oak stands growing in the observed region.

Introduction

The green oak leaf roller Tortrix viridana L. is a widely distributed leaf-eating monophagous species

in oak stands that is well-adapted to its host tree specie, Quercus robur var. praecox Czern. It also

damages other oak species both deciduous (Q. petraea, Q. cerris, Q. suber, Q. rubra) and evergreen (Q.

ilicifolia). The green oak leaf roller is distributed throughout the European part of Russia and in

many European countries, though it prefers conditions that occur in the steppe and forest-steppe

zones. Outbreaks of mass propagations of the green oak roller are durable and larvae and egg masses

are very tolerant to unfavourable biotic and abiotic factors. Larvae hatch over a period of 7 to 12

days. The lack of synchrony between hatching and oak budbreak or injury to young leaves caused by

spring frosts can cause reinforced migrations of larvae looking for food and therefore impact

significantly on their numbers. Larvae of both older and younger ages are not very mobile and move

within a crown only if food is absent. Nearly 90% of larvae often die because of this discrepancy and

are killed by predators and entomophages. A significant portion of the larval population is killed by

diseases caused by entomopathogens, however the magnitude of this mortality is usually not

catastrophic for the population. Males pupate before females (2-3 days) so when over-population

occurs, mortality of male pupae is less than what is incurred by female pupae. The total number of

pupae is an index of the state of the population and of the stage of an outbreak and depends on food

quality, weather conditions and population density. The total number of female pupae of the green

oak leaf roller depends directly on the level of crown defoliation.

The development of T. virdiana outbreaks depends significantly on survival in the larval and pupal

stages and consequently on weather conditions, the condition of the host tree, and biotic factors. A

delay in the development of larvae and pupae due to unfavorable conditions causes their increased

mortality and therefore is an important factor in the population dynamics of this species.

Materials and Methods

This study of T. viridana populations was conducted on permanent trees in the Tellerman oak grove

(the southern part of the forest-steppe zone, Voronezh oblast the Central Black Soil region of Russia),

an area characterized by a dry continental climate. Observations were initiated in 1969 by N.N.

Rubtsova and have been continued since 1975 by the authors.

Observations of the condition of trees and their crowns are made every year on 26 permanent plots

located over the area of the Tellerman Forest Experimental Station, Institute of Forest Science, to reveal

the locations of mass outbreaks of phyllophagous insects and to evaluate the status of crown defoliation.

Interrelations of Green Oak Leaf Roller Population and Common Oak:

Results of 30-year Monitoring and Mathematical Modeling

V.V. Rubtsov and I.A. Utkina

Institute of Forest Science, Russian Academy of Sciences, Uspenskoe, Moscow region, 143030 Russia
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 91

The most detailed study was conducted mainly in two types of forest: a) the floodplain lily-of-thevalley / dewberry oak stand (site index II, relative density 0.6-0.8, aged 85 years); b) the upland

solonets oak stand (site index IV-V, relative density 0.6-0.8, aged 80-95 years).

Counts of larvae and pupae were made individually on marked trees, by cutting sample branches

from the upper and lower parts of the crown. Butterflies and entomophages were raised in glass

containers in the laboratory. Counts of egg masses of T. viridana L. in the forest were made twice a

year, in October and March. In order to determine the mortality of eggs, larvae were allowed to hatch

from eggs that were sampled at different periods during their development (Rubtsov et al. 1989b).

Before discussing some features of the population dynamics of T.viridana and other phyllophages and

their impact on the condition of oak stands, we offer some discussion about the changing weather

conditions over the last 30 years. This is meaningful for understanding the potential impact of

climate and its relation to phyllophages and their host trees.

It is known that significant changes in weather and climate are occurring. We have analyzed various

weather parameters recorded in the vicinity of our investigations for last 50 years in order to reveal

some trends. Fig. 1 shows changes in three parameters selected for a growing season (from May to

September): mean air temperature, precipitation and hydro-thermal coefficient (the sum of

precipitation in mm divided by sum of air temperatures above 10°C multiplied by 0.1). It is evident

that mean air temperature has decreased by 2°C during the last 30 years, whereas precipitation over

the same period has increased by 110 mm. Consequently, the average hydro-thermic coefficient of a

growing season has increased by a factor of 1.7. Since the southern forest-steppe zone is a region with

Figure 1.—Some weather

characteristics over a growing

season (May-September)

Year
92 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

deficient moisture, the changing hydro-thermic regime during the growing season may be considered

favorable for vegetation. The consequences of these climatic changes have also influenced the state

and productivity of oak stands. Figure 2 illustrates the trend in the same three parameters for the

month of May. It is obvious that the mean air temperature and the hydro-thermic Coefficient has

declined by a factor of 2.4. Because May is the period when intensive feeding by larvae of T. viridana

and other early-spring phyllophagous insects occurs, these changing weather conditions should

clearly influence the relationship between phyllophagous insects and their host trees.

Results and Discussion

A mathematical model of the development of T. viridana populations was developed on the basis of

data obtained from the literature and from studies conducted by one of the authors (Rubtsov 1983,

1990). It interprets the mechanism of outbreak development in accordance with the synthetic theory

(Victorov 1965, Schwerdtfeger 1968). The model is non-linear, non-stationary, has alternating

structure and dimensions, and reflects the results of a series of complex interactions within the

modeled system. The mathematical model can be used to describe the dynamics of T. viridana

Figure 2.—Some weather

characteristics in May
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 93

populations and can be used to estimate the following parameters: the density, survival, fecundity,

and propagation coefficient of the population in each generation; defoliation and refoliation of

crowns in a stand; value and loss of stem increment, and some other parameters. The model

demonstrates that weather has a relative impact on the development of larvae and that the level of

crown defoliation decreases at higher population densities; if the population continues to increase,

i.e. a significant over-population occurs, the importance of weather factors again increases. Results of

the modeling demonstrate also that when severe over-population occurs, discrepancy (lack of

synchrony) between bud break and larval hatching can be favorable for survival of T. viridana

populations because it reduces the over-population; the extended period of hatching provides for the

successful development and survival of the remainder of the population. The results of our modeling

indicate that there is the possibility of large amplitudes of fluctuations in T. virdana population

density under certain conditions not only in the period of its mass propagation, but also when

populations are at low densities.

The main factors that are responsible for modifying and regulating populations of T. viridana were

considered in detail in earlier publications.(Rubtsov 1990, Rubtsov and Utkina 2001, and others).

Here we discuss only the importance of larval and pupal entomophages in regulating populations of

the green oak leaf roller. The species composition of these organisms in the Tellerman oak grove is

very rich. This can be explained in part by the complex composition of stands, their many-tiered

stratification, and the presence of many glades with flowering plants including cruciferous species.

The most abundant entomophagous species are as follows: Phaeogenes invisor Thunb., Itoplectis

alternans Grav., Apectis resinator Thunb., Apectis rufata Gm., Trichomma enecatur Rossi., Lissonota sp.,

Meniscus bilineator Grav., Elodia tragica Mg., Bessa fugas Rd., Dibrachys cavus Waiker., Habrocytus sp.,

Brachyimeria intermedia Nees., Monodontomerus minor Ratz., Apanteles sp. aff albipennis Nees.,

Apanteles sp., Microgaster laevisenta Thans.(Rubtsov and Rubtsova 1984).

The regulation of the population density of phyllophages can often be well described by means of

mathematical modelling. However, it is very difficult to forecast changes in population density due to

their stochastic and non-stationary nature. This decreases significantly the accuracy of forecasting.

After analyzing the features of fluctuating population numbers, we conclude that the green oak leaf

roller can be described as an eruptive species in accordance with Isaev et al. (1984). Figure 3 shows

the phase trajectories of T.viridana populations in the floodplain oak stand (A) and in the upland

solonets oak stand (B). The development of outbreaks in an eruptive pattern was observed in 1968-

1976, 1979-1987 in the floodplain stand. In the latter case, T.viridana was affected by a modifying

Figure 3.—Phase trajectories of green leaf roller’s population in floodplain oak stand (A) and

solonets oak stand (B). X – population density, K – propagation coefficient.
94 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

factor, a significant drought which occurred in 1979; the population expanded rapidly after this

occurrence.

However, the population did not reach its maximum due to the significant impact of another

modifying factor, severe winter frosts that occurred in 1984/1985 and affected populations of both T.

viridana and the entomophages that normally regulate its numbers. This is represented by the

formation of a loop in the phase portrait (Fig. 3A, 1984-1985). When studying phase portraits, a

conclusion can be made about the permanent character of outbreaks of the green oak leaf roller since

the population does not usually stabilize its numbers when the gradation cycle is over and a new

outbreak begins. Attention is drawn to the relative stability of population density and propagation

coefficients at similar stages of different gradation cycles in the solonets oak stand (Fig. 3B). The

highest population density is 20-32 and the lowest is 2-3.5 egg-masses per 1 m of a sample branch;

the maximum propagation coefficient is 5-7 and the minimum is 0.1-0.25. These features suggest

that the solonets oak stand is representative of a stable ecological regime and simplifies forecasting the

population development.

Before proceeding to the influence of phyllophagous insects on oaks, we should note that other leafeating insects, such as the gypsy moth and the winter moth occur also in stands of the Tellerman oak

grove. Their population dynamics are presented in Figure 4. Four outbreaks of both the gypsy moth

and the winter moth were recognized after the Second World War (Rubtsov et al. 1989a); permanent

monitoring of T.viridana populations began in 1969. The impact of T.viridana on the state and

growth of oak trees in a floodplain oak stand is shown in Figure 5. Values of stem increment and

percentage loss of increment averaged for a stand are plotted along with data on the population

density of T. viridana and defoliation estimates on individual trees. Figure 6 shows the results of

modeling the loss of increment of oaks as a function of a single and cumulative defoliation index in

four different stands by means of statistical regression analysis.

The most loss occurred in the upland and solonets stands: 40% after a single defoliation and 60%

after two consecutive defoliations. The cumulative defoliation, equal to 250-270% over three years,

caused nearly 100% loss of increment and significant mortality of trees. The least loss of increment

occurred in oaks of the floodplain stand, which can be explained by their tolerance of frequent and

significant insect defoliations and their increased ability to refoliate (Utkina and Rubtsov 1994).

The impact of crown defoliations on the seasonal growth activity of absorbing roots in oaks has been

studied during the past five year in collaboration with V.V. Mamaev (Mamaev et al. 2001, 2002).

Figure 7 shows the relation between the growth of absorbing roots of defoliated and non-defoliated

oak trees in 1998 in the floodplain stand. The defoliated trees incurred up to 90% defoliation while

Figure 4.—Population dynamics of some phyllophagous insects in the Tellerman

oak grove,

................Lymantria dispar L. : number of egg-masses per 50 trees

___ ___ ___Tortrix viridana L. : number of egg-masses per 5m of branch length

__________Operophthera brumata L. : number of imago females per 1 tree
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 95

the control trees were practically undamaged. The winter moth was the dominant leaf-eating insect

species responsible for the defoliation. Active regrowth of foliage began on May 28 and occurred very

rapidly. By June 18 the new foliage was very abundant and denser as compared to the foliage on the

undamaged trees. New leaves were not damaged by insects and mildew, appeared to be rather fresh

and were slightly different color as compared to spring foliage. The root system of the damaged trees

responded immediately to defoliation by producing intensive mycorhizae. However, as refoliation

occurred in early June, the rate of growth declined. The least amount of root growth occurred during

the period of most intense refoliation. The control trees experienced peak root activity during the

same period. Additionally, the amount of newly generated mycorhizae per 1 unit of soil volume was

more comparable to that which occurred on the control trees over the entire growing season. The

least difference between damaged and control trees was evident only in autumn.

The principal conclusions from this study suggest that the growth of new absorbing oak roots is

closely related to the condition of the crown and responds keenly to a loss of foliage, however, the

intensity of the response varies in trees that suffer single or repeated defoliations. In the first year of

severe defoliation, the root systems of trees respond by rapidly producing a mass of new mycorhizae

roots, however after repeated defoliations, there was no increase in this root growth activity. When an

abundance of oak mycorrhizae with well formed mycelia occurs in soil, this results in a significant

increase in the volume of absorbing root surface. This suggests on one hand that the weakening of

Figure 5.—Population dynamics of Tortrix viridana L. and its impact on

defoliation and stem increment in the floodplain oak stand.



Stem increment loss, % Stem increment loss, mm Defoliation, % Population density (eggs/1m branch)
96 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Figure 6.—Loss of radial increment in different oak stands in response to various level

of defoliation: A - single defoliation; B - repeated defoliation during two successive

years; C - repeated defoliation in three successive years. Numbers and different

symbols indicate stand type: 1- floodplain; 2 - riverbank; 3 - solonetz; 4 - upland.

trees and reduction assimilates and reserves occurs and, on the other hand, that oak trees respond to

the stress of repeated severe defoliations by engaging defensive mechanisms. It should be noted that

healthy trees have the highest growth activity of roots after defoliation occurs, whereas growth activity

of roots is less in weakened and suppressed trees and nearly absent in dying trees. The close

relationship between the development of new absorbing roots and the condition of crowns is one of

the ways by which trees survive under conditions of stress. During the last five years, oaks in the

floodplain and solonets stands suffered severe defoliation caused by the winter moth. These

defoliations combined with summer droughts in 2001 and especially in 2002, caused severe

weakening of oak trees and produced a micro-focus of decline. We are forecasting that these foci of

decline will expand next year since in the current year, the refoliation of trees and accumulation of

energy reserves in damaged trees was poor.

Acknowledgments

The study is supported by the Russian Fund for Basic Research (project 01-04-48276).

References Cited

Isaev, A.S., R.G. Khlebopros, L.V. Nedoresov, V.V. Kiselev, Yu.P. Kondakov. 1984. Population

Dynamics of Forest Insects. Nauka, Novosibirsk. [In Russian]

Cumulative % Defoliation

A

B

C
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 97

Mamaev, V.V., V.V. Rubtsov, I.A. Utkina. 2001. Impact of oak crown defoliation on growth activity

of absorptive roots. Lesovedenie ‡5: 43-49. [In Russian]

Mamaev, V.V., V.V. Rubtsov, I.A. Utkina. 2002. Seasonal dynamics of oak absorbing roots after

repeated defoliation in floodplain stands. Lesovedenie ‡5: 48-53. [In Russian]

Rubtsov, V.V. 1983. Mathematical model for development of leaf-eating insects (oak leaf roller taken

as an example). Ecological Modelling 18: 269-289.

Rubtsov, V.V. 1990. Some results of the study of the green oak leaf roller population in relation with

the modelling of its population dynamics, pp.210-225. In: S.E. Vompersky [ed.]. An experiment

and mathematical modeling for the study of forest and swamp biogeocenoses. Nauka, Moscow. [In

Russian]

Rubtsov, V.V. 1996. Influence of repeated defoliations by insects on wood increment in common

oak (Quercus robur L.). Ann. Sci. For. 53: 407-412.

Rubtsov, V.V., and N.N. Rubtsova. 1984. The analysis of interaction of leaf-eating insects and oak.

Nauka, Moscow [In Russian]

Rubtsov V.V., N.N. Rubtsova, I.A. Utkina. 1989a. The dynamics of some leaf-eating insects and

oak forests defoliation, pp. 97-116. In: V.V. Osipov [ed.]. The state of oak forests in the foreststeppe zone. Nauka, Moscow [In Russian]

Rubtsov V.V., N.N Rubtsova, I.A. Utkina. 1989b. Population dynamics of the green oak leaf roller

in the Tellerman oak grove. Lesovedenie ! 3: 46-54. [In Russian]

Schwerdtfeger F. 1968. Ökologie der Tiere. Z. Demökologie. Parey, Hamburg.

Utkina, I.A. and V.V. Rubtsov. 1994. Refoliation of common oak after insect damage. Lesovedenie

No.3: 23-31. [in Russian]

Victorov, G.A. 1965. Variations of insect population dynamics as regulated process. Zhurnal

Obshchei Biologii (Journal of General Biology) 24: 43-55. [in Russian]

Figure 7.—Dynamics of new growth of young absorbing oak roots in the

floodplain oak stand after insect defoliation in 1998

— — — — trees without defoliation (control)

————— trees with 90 % defoliation
98 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

The larvae of Dendrolimus pini L. and Panolis flammea (Den. et Schiff.) usually occur in high

numbers on different trees within a stand. Studies that focused on the host tree-preference of these

two species were conducted in the Wymiarki Forest District (Poland) in 2001. Sixteen Scots pine

trees were selected to estimate the larval abundance of both species using 1x1 m collectors. In June

the trees were cut down, the larvae in crown were counted and the samples of needles for chemical

analysis were taken from the lower, middle and upper parts of the crowns. Natural radiation was

measured under each tree using the methods developed by dowsers (radiesthets). There were no

significant differences in the concentrations of any terpene or phenolic acid in different parts of

crowns. The abundance of pine moth larvae was related significantly with 7 monoterpenes, 6

sesquiterpenes and 5 phenolic acids, while the abundance of the pine beauty moth was related with 5

monoterpenes, 6 sesquiterpenes and 1 phenolic acid. There were 6 compounds which had significant

impact on the abundance of both species: â-pinene was in positive relationship with D. pini and

inverse with P. flammea, while the compound with a retention index of 1430, ã-muurolene, âvetivenene, á-cadinene and protocatechuic acid were in inverse relationships with D. pini and positive

with P. flammea. These differences may explain why these insect species are rarely observed in high

numbers on the same trees. Natural radiation is possibly one of the causes of variation of secondary

metabolites in Scots pine needles. It was in significant relationships with 9 monoterpenes, 3

sesquiterpenes and 1 phenolic acid. The results of studies suggest that â-pinene and sesquiterpene

with a retention index of 1430 are the only links between natural radiation and abundance of both

D. pini and P. flammea.

Key words: Dendrolimus pini, Panolis flammea, host preference, secondary metabolites, terpenes,

phenolics, natural radiation

The pine moth, Dendrolimus pini L., and pine beauty moth, Panolis flammea (Den. et Schiff.), belong

to a group of the most harmful defoliators of Scots pine, Pinus sylvestris L., in Poland. Both species

have a one-year life cycle however their biologies are different.

The pine moth females lay eggs in July-August. Young larvae feed before late-October or earlyNovember, overwinter in forest litter, and resume feeding in early spring on old needles. After all of

the old needles are consumed, the larvae start to feed on young needles. The larvae pupate in June

through August (Vorontsov 1982, Kolk and Starzyk 1996).

The pine beauty moth overwinters as a pupa. Adults emerge in April-May, mate, and females deposit

egg masses. The young larvae emerge and begin feeding in late-May on buds, needles and bark of

fresh shoots. The older larvae feed on old needles and pupate in late June-July.

Both species prefer 20-80 year old pine monocultures, however their outbreaks usually occur in

different stands; if both species occur within a stand, high numbers of their larvae are observed on

different trees. This observation led us to hypothesize that needle quality (concentration of secondary

Host-tree Preferences of the Pine Moth (Lepidoptera: Lasiocampidae)

and Pine Beauty Moth (Lepidopera: Noctuidae) Larvae in Relation

to Needle Quality

Lidia Sukovata,1 Andrzej Kolk,1 Jadwiga Jaroszynska,2 Urszula Krajewska,2

Agnieszka Purzynska and Valerii Isidorov 2

1

Forest Protection Department, Forest Research Institute, Sekocin Las, 05-090 Raszyn, Poland,

 e-mail: L.Soukovata@ibles.waw.pl 2

Institute of Chemistry, University in Bialystok, 11/4 J. Pilsudski Ave., 15-443 Bialystok, Poland
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 99

metabolites) could be of a great importance in the host tree preference of the pine moth and pine

beauty moth larvae.

On the other hand, the terpene components of coniferous resin systems are under strong genetic

control and are valuable indicators of population diversity. Moreover, they interact with other

components of the ecosystem and are thus of great value as adaptive markers (Forrest et al. 2000). All

components of ecosystems are also under the impact of cosmic radiation, and geomagnetic, electric,

electromagnetic and gravitational fields of the earth. Concentrations of minerals, underground

streams of water, geological downcasts et al. cause the anomalies in these fields (Krolicki 1998),

which may have an impact on the distribution of living organisms and their condition, biodiversity

of ecosystems, and variability within a population.

Several studies on the impacts of different fields of the earth on some insect species were conducted

in Austria and some other countries in the late 60s – early 80s of the last century (Schneider 1960,

Robert 1963, Becker 1964, 1971, Schimitschek 1972, Jahn and Nessler 1971). Some studies by Jahn

(1973, 1975, 1977) focused on the impact of natural radiation on nun moth survival and fecundity.

Natural radiation was considered to be an electromagnetic radiation of very low frequency. The

mortality of young nun moth larvae inside the zone of high radiation was significantly lower than in

the normal zone. The mortality of young larvae reared on plants from the zone of high radiation was

significantly lower and the fecundity of females was significantly higher than from those plants reared

from the normal zone. These results suggest that there might be some direct relationships between the

natural radiation of the earth and the occurrence of the defoliators or indirect through the impact of

the radiation on the insect host trees. This hypothesis was also tested in our studies.

Material and Methods

Study Site

The studies were conducted in the Wymiarki Forest District of Regional Directorate of State Forests,

located in the south western part of Poland. Scots pine stands (38-44 years of age) of similar quality

and growing on similar site conditions, occur on an area of about 1500 ha. The threat of these stands

from the pine moth and pine beauty moth in 2001 was assessed to be high, and therefore chitin

synthesis inhibitors were applied on May 17 to prevent heavy defoliation of trees. The threat

assessment revealed also that the pine moth was more abundant in some stands than in others while

the pine beauty moth was more numerous in the stands where the abundance of pine moth was low.

Insect abundance was estimated on 16 trees and samples of needles from each of the trees were taken

for chemical analysis.

Estimation of Insect Abundance on Sampled Trees

One meter square collectors were placed beneath each of the selected trees at the time that the spray

was applied so that dying insects fell into the collectors. One month later, on June 17, 2001, the trees

were felled onto cotton sheets and the larvae of all species found in the crowns and on the sheet were

counted.

Chemical Analysis of Needles

Chemical analysis was conducted to estimate the concentration of essential oils (monoterpenes and

sesquiterpenes) and phenolics in the needles of the selected Scots pine trees. The samples of previous

year needles were taken on June 17, 2001, from lower, middle and upper parts of crown of each tree

in order to check the possible differences in the concentration of secondary metabolites among them.

Analysis of the composition and concentration of monoterpenes and sesquiterpenes was conducted

using GC/SPME and GC/MS methods. The concentration of phenolics was analyzed using the GC

method. The analyses were conducted using HP 4890D chromatograph with FID detector (on DB-5

column, 30 m x 0,25 mm ID). The temperature program for analyzing phenolics was from 50 to
100 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

300oC with a rate increase of 3oC/min. For essential oils, the program was from 40oC to 200o with a

rate increase of 3oC/min followed by a rate increase of 10o

C/min up to 300oC.

Measuring Natural Radiation

To determine the natural radiation, we used the method of Jahn (1974, 1977), which is known as the

radiesthetical (dowsing) method. It is based on using a pendulum and scale specially developed by the

radiesthets. In this case the natural radiation was measured in oSRW (Swaczyna 1991).

Statistical Analysis

Relationships between the concentration of each chemical compound and the number of specimens

of each insect species, and the relationship between the natural radiation and the concentration of

each chemical compound were analyzed with regression analysis using the statistical package Statistica

5.1/98 (StatSoft Poland). To decrease the variation of variables and to achieve a normal and

homoscedastic distribution of points around the regression line, either or both variables were

submitted to a logarithmic transformation.

Results

Insect Abundance

The number of the pine moth larvae on the trees varied from 0 to 90 specimens ( N =24,6±25,93),

while the number of the pine beauty moth varied from 0 to 598 specimens ( N =94,4±185,18).

There was an inverse relationship between the abundances of these two species on the selected trees

(Fig. 1).

Secondary Metabolites

There were 28 monoterpenes, 29 sesquiterpenes and 18 phenolics in the needles sampled from 16

selected trees. The most common compounds which were used for the statistical analysis, are

presented in Table 1. There were no significant difference among the concentrations of any

compound measured in different parts of the crown, thus we used measurements from the middle of

the crown in the data analysis.

Figure 1.—The relationship between the ln-transformed abundances of

the pine moth and pine beauty moth larvae on 16 selected Scots pine

trees in the Wymiarki Forest District in 2001

Correlation coefficient r = -0,5196

 LN (NP.flammea)

LN (N

D.pini

)

0

1

2

3

4

5

-1 0 1 2 3 4 5 6 7
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 101

Insect Abundance on Trees and Secondary Metabolites in Needles

Monoterpenes. Regression analysis of the concentrations of monoterpenes in needles and the

abundance of the pine moth revealed that 7 monoterpenes were related to the number of the pine

moth larvae per tree (Table 2).

One of them, β-pinene, was related positively with the abundance of pine moth larvae, while all of

the others were related inversely. The strongest correlation between the variables was observed for

camphene (r=-0.72), β-pinene (r=0.85) and trans-sabinyl-acetate (r=-0.80).

The abundance of the pine beauty moth larvae on trees was significantly and positively related to the

concentrations of sabinene, RI 1037 and RI 1340 and inversely related with β-pinene and (E)-βocimene (Table 3).

Sesquiterpenes. Significant relationships were found between 6 sesquiterpenes and the number of pine

moth larvae (Table 4), and 6 sesquiterpenes and the number of the pine beauty moth larvae on trees

(Table 5). For the former species, all sesquiterpenes were inversely related with larval abundance and

for the latter species, they were positively related with larval abundance.

Phenolics. Regression analysis revealed that the number of pine moth larvae on trees was significantly

inversely-related with the concentrations of 4 phenolics extracted from the needles while positively

related with gallic acid (Table 6). In case of the pine beauty moth, the only phenolic that was related

to the abundance of larvae was protocatechuic acid and this relationship was positive [lnN = 0.67 x ln

(protocatechuic acid), r=0.71, R2

=0.46].

Table 1.—Composition of the most common secondary metabolites in

the needles sampled from 16 selected Scots pine trees in the Wymiarki

Forest District, Poland, in June 2001.

Monoterpenes Sesquiterpenes Phenolics

3-hexene-1-ol longicyclene Vanillic

tricyclene RI 1386 Homovanillic

RI 925* β-longipinene Protocatechuic

α-pinene (E)-caryophyllene Homogentisic

camphene RI 1430 m-coumaric

sabinene RI 1441 p-coumaric

β-pinene (E)-β-farnesene o-coumaric

myrcene RI 1475 Gallic

3-carene γ-muurolene Phenol

α-terpinene RI 1483

limonene β-selinene

RI 1037 RI 1494

(E)-β-ocimene RI 1502

γ-terpinene (Z)-γ-bisabolene

terpinolene Â-vetivenene

m-cymene α-cadinene

Bornyl acetate RI 1581

trans-sabinyl-acetate Conipferyl alcohol

RI 1340

α-terpinyl-acetate

*- undetermined compound with a retention index (RI)
102 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Table 2.—Regression models of the number of Dendrolimus pini larvae and

monoterpenes in the needles of Scots pine trees (with p<0.05)

Monoterpene Correlation Regression model Determination

coefficient coefficient

camphene -0.72 lnN = 4.7 - 0.87 x camphene 0.52

β-pinene 0.85 lnN = 1.51 x ln(β-pinene) 0.69

α-terpinene -0.59 lnN = 4.2 - 11.79 x α-terpinene 0.35

γ-terpinene -0.60 lnN = 4.6 - 6.49 x γ-terpinene 0.35

terpinolene -0.59 lnN = 4.3 - 15.48 x terpinolene 0.35

m-cymene -0.60 lnN = 4.3 - 0.64 x m-cymene 0.35

trans-sabinyl-acetate -0.80 lnN = -1.21 x ln(trans-sabinyl-acetate) 0.59

Table 3.—Regression models of the number of Panolis flammea larvae and

monoterpenes in the needles of Scots pine trees (with p<0.05)

Monoterpene Correlation Regression model Determination

coefficient coefficient

sabinene 0.71 lnN = 6.75 x sabinene 0.46

β-pinene -0.69 lnN = 5.51 – 1.64 x ln (β-pinene) 0.48

(E)-β-ocimene -0.68 lnN = 3.3 - 1.8 x ln ((E)-β-ocimene) 0.46

RI 1037 0.73 lnN = 46.56 x RI 1037 0.49

RI 1340 0.75 lnN = 0.35 + 12.26 x RI 1340 0.53

Table 4.—Regression models of the number of Dendrolimus pini larvae and

sesquiterpenes in the needles of Scots pine trees (with p<0.05)

Sesquiterpene Correlation Regression model Determination

coefficient coefficient

RI 1430 -0.78 lnN = 4.65 - 12.26 x RI 1430 0.56

γ-muurolene -0.66 lnN = 4.4 - 2.48 x γ-muurolene 0.39

RI 1494 -0.78 lnN = -1.76 x ln(RI 1494) 0.57

RI 1502 -0.85 lnN = 2.9 - 0.81 x ln(RI 1502) 0.70

β-vetivenene -0.79 lnN = 5 - 0.57 x β-vetivenene 0.58

α-cadinene -0.84 lnN = 5.2 - 18.5 x α-cadinene 0.67

Table 5.—Regression models of the number of Panolis flammea larvae and

sesquiterpenes in the needles of Scots pine trees (with p<0.05)

Sesquiterpene Correlation Regression model Determination

coefficient coefficient

RI 1386 0.77 lnN = 6.85 + 1.58 x ln (RI 1386) 0.55

RI 1430 0.87 lnN = 27.71 x RI 1430 0.74

γ-muurolene 0.76 lnN = 7.27 x γ-muurolene 0.53

(Z)-γ-bisabolene 0.65 lnN = 1.45 x (Z)-γ-bisabolene 0.38

β-vetivenene 0.80 lnN = 1.55 x β-vetivenene 0.60

α-cadinene 0.85 lnN = 28.08 x α-cadinene 0.69
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 103

Among the compounds analyzed, 1 monoterpene, 4 sesquiterpenes and 1 phenolic acid were related

to the abundance of larvae of both the pine moth and pine beauty moth (Table 7).

When the coefficients of correlation among these compounds and both insect species were compared,

it was revealed that there was a difference in preferences of needles by larvae of the pine moth and

pine beauty moth (Table 7). The abundance of pine moth larvae was positively related to â-pinene

and inversely related to all other common compounds, while the pine beauty moth larvae preferred

needles with a lower concentration of β-pinene and higher concentrations of other compounds.

Natural Radiation and Secondary Metabolites

Natural radiation measured under selected trees varied from 40 to 2100 oSRW ( R =898,75832,16).

There was a significant relationship between natural radiation and the concentration of some

monoterpenes (Table 8), sesquiterpenes and 1 phenolic acid (Table 9) in the needles of selected Scots

pine trees. These relationships were inverse for most monoterpenes, while positive for 3-hexene-1-ol,

RI 1037 and (E)-β-ocimene, all 3 sesquiterpenes and homovanillic acid.

Discussion

The only studies on the relationship between monoterpenes and the pine moth larvae were

conducted by Smeljanec (1969), and Rudnew and Smeljanez (1969). They revealed that camphene,

â-pinene and borneol had positive effects on larval development while α-pinene, α-terpineol,

limonene and bornyl acetate had negative effects. Our results are somehow contradictory as

camphene was inversely related with the number of the larvae per tree, while the relationships with αpinene, limonene and bornyl acetate were not significant. Only one compound, β-pinene, was

positively related with the larvae of the pine moth in both studies.

Table 6.—Regression models of the number of Dendrolimus pini larvae and phenolics in

the needles of Scots pine trees (with p<0.05)

Sesquiterpene Correlation Regression model Determination

coefficient coefficient

Homovanillic -0.74 lnN = 4.30 - 0.82 x ln (homovanillic) 0.55

Protocatechuic -0.69 lnN = 4.96 - 0.42 x ln (protocatechuic) 0.47

o-coumaric -0.76 lnN = 6.48 - 1.02 x ln (o-coumaric) 0.57

Phenol -0.78 lnNl = 7.46 - 1.49 x ln (phenol) 0.41

Gallic acid 0.70 lnN = 0.67 x ln (gallic) 0.61

Table 7.—Coefficients of correlation between the number of Panolis flammea and

Dendrolimus pini larvae and chemical compounds related to both insect species

Type of chemicals Compound Correlation coefficient for

Dendrolimus pini Panolis flammea

monoterpene β-pinene 0.97 -0.69

sesquiterpene RI 1430 -0.78 0.87

γ-muurolene -0.66 0.76

β-vetivenene -0.79 0.80

α-cadinene -0.84 0.85

phenolic acid protocatechuic -0.69 0.71
104 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Studies on the effect of monoterpenes in Scots pine needles on the pine beauty moth were conducted

by Leather (1987), however it concerned the oviposition preference by the female moths. The results

of these studies suggest that eggs are laid more often on the needles of Scots pines which contained a

high ratio β:α-pinene. This leads to an assumption that pine beauty females prefer to lay eggs on

those trees which are most favorable for larvae of the next generation. Our results suggest that the

needles of preferable trees should contain low amount of β-pinene and thus the ratio β:α-pinene

should be low since there was no significant relationship between α-pinene and the number of the

pine beauty moth larvae per tree.

The differences between the host tree preferences of D. pini and P. flammea larvae haven’t been

studied before. Six chemical compounds were identified that were significantly but oppositely related

with the larval abundance of both insect species: β-pinene was related positively with D. pini but

inversely with P. flammea, while the compound with a retention index of 1430, γ-muurolene, βvetivenene, α-cadinene and protocatechuic acid were related inversely with D. pini and positively

with P. flammea. These differences may help to explain why these two species are rarely observed in

high numbers on the same trees.

The possible impact of natural radiation, though measured using a subjective method, on the

chemical composition of the Scots pine needles and indirectly on insect occurrence was also

investigated for the first time. A significant relationship was found for natural radiation and 9

monoterpenes, 3 sesquiterpenes and 1 phenolic acid. When natural radiation is included in a plantTable 8.—Regression models of natural radiation and monoterpenes in the needles of

Scots pine trees (with p<0.05)

Monoterpene Correlation Regression model Determination

coefficient coefficient

3-hexene-1-ol 0.77 3-hexene-1-ol = 0.042 x ln(rad) 0.55

RI 925 -0.65 RI 925 = 0,34 - 0.036 x ln(rad) 0.37

β-pinene -0.69 ln(β-pinene) = 3.48 - 0.38 x ln(rad) 0.47

3-carene -0.70 3-carene = 57.8 - 6.42 x ln(rad) 0.49

α-terpinene -0.66 α-terpinene = 0.24 - 0.022 x ln(rad) 0.43

RI 1037 0.82 RI 1037 = -0.14 + 0.03 x ln(rad) 0.66

(E)-β-ocimene 0.74 ln((E)-β-ocimene) = -2.63 + 0.43 x ln(rad) 0.54

terpinolene -0.73 terpinolene = 0.26 - 0.03 x ln(rad) 0.53

m-cymene -0.63 m-cymene = 4.04 - 0.34 x ln(rad) 0.40

Table 9.—Regression models of natural radiation and sesquiterpenes and phenolics

in the needles of Scots pine trees (with p<0.05)

Compound Correlation Regression model Determination

coefficient coefficient

Sesquiterpenes

RI 1386 0.72 ln(RI 1386) = -4.13 + 0.4 x ln(rad) 0.47

RI 1430 0.82 RI 1430 = -0.17 + 0.047 x ln(rad) 0.64

RI 1494 0.74 ln(RI 1494) = -4.35 + 0.29 x ln(rad) 0.50

Phenolic acid

homovanillic 0.70 ln(homovanillic) = 0.614 x ln(rad) 0.44
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 105

insect system, the interactions are getting more simple. The sesquiterpene with a retention time of

1430 and β-pinene seem to be the only links between natural radiation and abundance of both D.

pini and P. flammea. Both compounds were inversely dependent on natural radiation, while they had

different effects on the larval abundance of these species. These results suggest that natural radiation

can have some impact on host plants and the larvae that feed upon them.

Further studies should focus on sampling more trees for analyses to confirm the results obtained so

far and on using subjective and available objective methods to explore the relationships with natural

radiation.

Acknowledgments

We thank Tomasz Jablonski and Slawomir Lipinski from Forest Research Institute in Warsaw, and the

staff from the Wymiarki Forest District for technical assistance. This research was supported by

Polish State Forests, project BLP-211.

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Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 107

Abstract

The brown spruce longhorn beetle, Tetropium fuscum (Fabr.) (Coleoptera: Cerambycidae) recently

became established in Halifax, Nova Scotia, Canada, where it is infesting and killing apparently

healthy red spruce, Picea rubens Sarg. In its native range, T. fuscum is a secondary pest of Norway

spruce, Picea abies L., breeding in recently felled trees or trees weakened by root rots, lightning or

other factors. To test the relationship between tree vigor and susceptibility to infestation by T.

fuscum, we felled 18 pairs of infested and uninfested red spruce in the winter of 2001 in Point

Pleasant Park, Halifax, and measured radial growth rates as a correlate of vigor. Mean 5-year radial

increment peaked in 1956-1960 and declined steadily thereafter for all red spruce. However, radial

growth was significantly lower in attacked trees than in unattacked trees in seven of nine 5-year

periods between 1956 and 2000. Our data indicate that red spruce with reduced growth rates and

low vigor were more susceptible to infestation by T. fuscum than faster growing, more vigorous trees.

In March of 2000, it was determined that the brown spruce longhorn beetle, Tetropium fuscum

(Fabr.) (Coleoptera: Cerambycidae), had established in Point Pleasant Park, Halifax, Nova Scotia

(Smith and Hurley 2000), and was infesting and killing apparently healthy red spruce, Picea rubens

Sarg. The park is 75 ha in size, most of which is forested, with red spruce being the most common

conifer species. The year of introduction is unknown, but recent examination of Tetropium

specimens from the Nova Scotia Museum of Natural History revealed that 17 specimens of T. fuscum

(misidentified as the native T. cinnamopterum Kirby) had been collected in a naturalist’s bark beetle

survey of Point Pleasant Park in 1990. Route of entry is uncertain but T. fuscum adults likely

emerged from softwood packing material from shipping containers in the Halifax port facility

located directly adjacent to Point Pleasant Park. Tetropium fuscum has been found in solid wood

packing material at the ports of Montreal and Vancouver (Smith and Humble 2000, Humble and

Allen 2001) and it is possible that the Halifax population is the result of more than one

introduction. The chronology of the beetle’s discovery in Halifax is described in Sweeney et al.

(2001) and at the following website: http://www.atl.cfs.nrcan.gc.ca/BSLB/chronologye.htm#july1998. A large scale survey and eradication program began in 2000 under the lead of the

Canadian Food Inspection Agency.

Tetropium fuscum is native to coniferous forests in northern and central Europe, and western Siberia.

Its main host is Norway spruce, Picea abies (L.) Karst., but it has also been found on P. sitchensis

(Bong.) (Francke-Grosman 1954) Carr., P. pungens Engelm. (Juutinen 1953), Pinus sylvestris L.

(Reineck 1919),–Abies alba L. and Larix spp. (Schaufuss 1916). In Halifax, T. fuscum is infesting red

spruce, white spruce (P. glauca (Moench) Voss), black spruce (P. mariana (Mill.) B.S.P.), and Norway

spruce. Larvae feed in the phloem and cambium, producing an extensive network of irregular

galleries that eventually girdle the stem. It is univoltine, overwintering as a larva in most of its range,

but may require 2 years to complete its life cycle in cooler climates or when the nutritional quality of

the host is poor (Schimitschek 1929). Trees are often reinfested annually until desiccation and death

(Juutinen 1955).

Radial Growth Rate and Susceptibility of Picea rubens

Sarg. to Tetropium fuscum (Fabr.)

K. O’Leary1, J.E. Hurley2, W. Mackay2 and J. Sweeney2,3

1

Faculty of Forestry and Environmental Management, University of New Brunswick,

Fredericton, NB, Canada 2

Natural Resources Canada, Canadian Forest Service-Atlantic Forestry Centre,

PO Box 4000, Fredericton, NB, Canada, E3B 5P7 3

Presenter
108 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Tree Health and Susceptibility to T. fuscum Infestation

In its native range, the brown spruce longhorn beetle, T. fuscum is a secondary pest, breeding in

recently felled trees or live trees weakened or stressed by biotic or abiotic factors such as root rots

(Juutinen 1955) or lightning (Kula and Z ́becki 1997). In Halifax, however, investigations in 1999

and 2000 in Point Pleasant Park found little evidence for a direct association between root disease

and T. fuscum attack. Although both Armillaria ostoyae (Romagnesi) Herink and Inonotus tomentosus

(Fr.:Fr.) S. Teng. were present at many scattered locations in the park, examination of the stumps of

T. fuscum-attacked and non-attacked trees for wood stain and decay at ground line did not reveal any

consistent pattern (G. Warren and Ken Harrison, pers. comm.). However, it is possible that the many

root disease centers within the park created a reservoir of stressed, susceptible hosts that allowed the

T. fuscum population to build to levels at which both stressed and non-stressed hosts became infested

(Gary Warren, pers. comm.). A wood stain fungus, Ophiostoma tetropii Mathiesen, has been found

associated with T. fuscum infestation in Halifax (Jacobs et al. 2003); it appears to be only weakly

pathogenic but its biology is poorly known and currently under investigation (Doug Strongman and

Ken Harrison, pers. comm.).

Juutinen (1955)1

 rated the health or “desiccation” status of 39 Norway spruce trees recently infested

with T. fuscum in northern Finland as follows:

Health Description Distribution of

rating T. fuscum-attacked trees (%)

I Completely healthy trees. 0

II Onset of desiccation. Desiccation factors are

sparse and do not appreciably affect the condition

of the tree as a whole. Crown completely without 4.1

discoloration and the tree— except for possible

traces of activity by woodpeckers and slight resin

flow— by and large resembles a healthy tree externally.

III Desiccation further advanced. Desiccation factors

are more prominent, but are not yet able to cause

desiccation of the tree. Symptoms of desiccation 74.3

are already discernible externally, the crown is thinned

and already partly dried up.

IV Desiccation factors already present to such an extent

that rapid desiccation of the tree appears certain. 21.6

Crown only partly green.

V Desiccation just completed. Crown completely dry,

but still some fresh parts here and there in the bark. 0

VI Completely withered trees. Crown and bark dried up

throughout. 0

Juutinen (1955) found that most T. fuscum-infested Norway spruce had “thinned...and partly dried

up” crowns (category III); only 4% of infested trees appeared green and healthy (II) with “slight resin

flow.” It is worth noting that Juutinen considered most of these trees (in categories II and III) as sublethally weakened, i.e., “not yet able to cause desiccation of the tree,” prior to T. fuscum infestation.

1

English translation available from NRCAN-CFS, Atlantic Forestry Centre
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 109

He states: “Especially after outbreaks of caterpillars, the spruce longhorn beetles attacked trees which

could have undoubtedly recovered and they therefore caused considerable economic damage.”

(Juutinen 1955). So even in its native range, it appears that T. fuscum does not infest only dying trees

but also attacks trees undergoing temporary periods of stress or low vigor. Once infested by T. fuscum,

however, eventual girdling of the stem increases the tree’s susceptibility to other pests, and results in

death within 1 to 5 years of infestation (Juutinen 1955). 

In contrast, the majority of T. fuscum-infested red spruce in Halifax appear green and healthy with

copious resin flow down the stem. Hurley and MacKay (2000) assessed the crown condition and the

presence or absence of signs of T. fuscum infestation on 115 red spruce (selected by prism point

samples) in Point Pleasant Park on 3 May 2000. Crown condition was visually rated using

standardized Canadian Forest Service forest health survey methods (D’Eon et al. 1994) on a scale

from 1 to 9, where 1 = no defoliation and 9 = dead for more than a year. Most of the trees surveyed

were classified as either green and healthy (67%) or dead for more than a year (25%). Less than 10%

of live trees exhibited more than 25% defoliation (Table 1). Signs of T. fuscum infestation, i.e., resin

flow on the stem and exit holes, were present on almost 50% of the trees with healthy crowns (classes

1–3) and on more than 80% of dead trees. It is difficult to directly compare the two methods of tree

health classification, but we suggest that most of the infested trees in our park survey would

correspond to Juutinen’s health rating of II, i.e., “Crown completely without discoloration ... By and

large resembles a healthy tree externally.” For whatever reason, red spruce infested by T. fuscum in

Halifax appeared healthier than T. fuscum-infested Norway spruce in Finland.

A green and full crown is not always indicative of tree health or vigor, e.g., completely girdled trees

may remain green for several months until the roots begin to weaken and die due to lack of

photosynthates. Radial growth rate is related to vigor in red spruce; average 10-year radial increments

of 2.3 and 0.75 cm are rated as superior and inferior vigor, respectively (Blum 1990). To investigate

the relationship between tree vigor and susceptibility to infestation by T. fuscum, we compared the

radial growth rates of infested and uninfested red spruce in Point Pleasant Park, NS. If T. fuscum was

infesting red spruce regardless of health status or vigor, then the radial growth rate preceding

infestation should be similar in infested and uninfested trees.

Methods

Twenty pairs of spruce trees were selected and tagged in Point Pleasant Park, Halifax, NS, in the fall

of 2000. Each pair consisted of a tree with external signs of T. fuscum infestation, e.g., resinosis and

exit holes, and a tree without such signs, hereafter referred to as attacked and unattacked, respectively.

Table 1.—Crown condition and infestation by Tetropium fuscum of red spruce, Picea rubens

in Point Pleasant Park, Halifax, NS, 3 May 2000 (Hurley and MacKay 2000)

Crown Crown description No. red spruce No. with T. fuscum signs

class (% of total) (% within class)

1 no defoliation 4 (3.5) 1 (25.0)

2 < 25% defol. current foliage only 0 (0) 0 (0)

3 < 25% defol. all foliage 73 (63.5) 35 (47.9)

4 25-50% defoliation 5 (4.3) 4 (80.0)

5 51-75% defoliation 4 (3.5) 0 (0)

6 76-90% defoliation 0 (0) 0 (0)

7 > 90% defoliation 0 (0) 0 (0)

8 recent dead 0 (0) 0 (0)

9 old dead 29 (25.2) 24 (82.7)
110 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Within pairs, trees were selected to have the same (± 2 cm) diameter at breast height (dbh) and were

growing within 1–15 m of each other. For each tree, the crown condition and canopy position were

rated and the north-facing side of the bole was marked. Trees were felled in January 2001 and length

of live crown, total height, and live crown ratio were measured. After felling, we learned that one tree

in each of two pairs was white spruce instead of red spruce. Therefore, only 18 pairs of red spruce

were included in this analysis. A line was marked along the north (or nearest to it) face of the length

of the bole and 4–5 cm thick disks were sampled from the center of every 4th discernible internode,

and every 0.5 m thereafter. Wood disks were stored at -10oC until radial increments were measured.

Two measures of radial increment (on both radii along the north–south line marked on the bole)

were recorded for each year of growth per disk using a stereomicroscope and a Holman Digi-mic

(Holman Electronic Controls Ltd., Fredericton, NB). Ring widths were subsequently checked and remeasured using a high resolution scanner and the “WinDENDRO TM 2001a” software package

(Regent Instruments Inc., www.regentinstruments.com), which also allowed us to save an electronic

image of each tree disk. Although increments were measured along the north–south radii, the entire

disk surface was examined under the stereomicroscope to check for discontinuous or incomplete

rings. Rings that discontinued along a north or south radius were given an radial increment of zero.

For the purpose of this analysis, we assumed there were no completely missing rings and dated the

rings using the outermost ring (assumed as year 2000) as a reference. However, missing rings are not

uncommon, especially near the base of older, slow-growing trees (Glock 1937). If some of the trees

did have missing rings, then the actual year of growth will have been assigned incorrectly, and we will

have overestimated some of the 5-year periodic increments for those trees. For example, what we

estimated as a 5-year increment may really have represented 6 or 7 years of growth. However, the

possibility of missing rings does not seriously affect the main (null) hypothesis tested in this paper,

i.e., that attacked and unattacked trees have similar growth rates or vigor. If attacked and unattacked

trees are of similar age and vigor, then the probability of having missing rings will be the same. If

attacked trees are truly older and less vigorous than unattacked trees, the probability of missing rings

(and of overestimating growth and underestimating age) is greater in the attacked trees, resulting in a

more conservative test of the our null hypothesis. We plan to use cross-referencing to accurately date

rings and conduct a complete stem analysis of these trees in a subsequent paper.

To check the accuracy of our designation of attacked and unattacked trees, we collected one or two

35-cm bolts from each of 11 attacked trees and seven unattacked trees. Bolts were stored at -10oC

and subsequently incubated at 21°C in a containment facility and the emergence of adult T. fuscum

recorded daily.

In the present analysis, we calculated the mean radial increment per 5-year period, e.g., 1996-2000,

from the breast height disk of each tree. Live crown ratio, age (estimated from the bottom-most disk),

crown condition, dbh, and height, were compared between attacked and unattacked trees, using

paired t-tests. Periodic radial increment (PRI) for each of 19 5-year periods, from 2000 back to 1906,

were compared between attacked and unattacked trees using ANOVA, with tree-pair locations as

blocks. Residuals were checked for normality using the Shapiro-Wilk test (Zar 1984, SAS 1999-

2001). The periodic annual increment of red spruce normally peaks at about age 45 (Meyer 1929).

To account for a negative correlation between tree age and radial growth rate, we included age as a

covariate and compared the PRI of attacked and unattacked trees for each 5-year period between

1960 and 2000, when most trees were more than 45 years old.

Results and Discussion

Adult T. fuscum emerged from bolts from seven of 11 attacked trees; bolts from the four attacked

trees that did not produce adult T. fuscum had been stored at -10°C for more than 6 months and it is

possible that prolonged exposure to cold caused some mortality. No T. fuscum emerged from the bolts

sampled from the seven unattacked trees. Because T. fuscum may reinfest the same host tree year after

year, it is possible that some of the attacked trees had been infested before 1999. However, as trees
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 111

usually die within 1 to 5 years after first becoming infested (Juutinen 1955), it is unlikely any of the

sample trees were infested before 1996.

By design, trees within pairs did not differ in dbh, but attacked trees were on average 9 years older,

and had slightly worse crown condition than unattacked trees (Table 2). The overall mean 10-year

radial increment at breast height for the period from 1960-2000 was 1.5 cm, which for red spruce

corresponds to a vigor class between acceptable (1.2 cm) and good (1.65 cm) (Blum 1990). The

mean age at peak PRI did not differ between attacked (43 years) and unattacked trees (40 years) and

was similar to that reported for second-growth red spruce (Meyer 1929). Mean PRI peaked in 1956-

1960 and declined steadily afterwards for both attacked and unattacked red spruce (Fig. 1). A similar

decline in growth rate was observed for red spruce across the Adirondack and northern Appalachian

Mountains (Johnson and Siccama 1983; Hornbeck and Smith 1985). Cook and Zedacker (1992)

concluded that neither stand dynamics nor climate change, alone or in combination, could be

accepted as the cause of the regional decline in red spruce. Johnson et al. (1992) suggest that air

pollution has played a significant role in the decline of red spruce in eastern North America, by

increasing the sensitivity to winter injury, aluminum mobilization and cation loss. The soil in Point

Pleasant Park is a podzol derived from Precambrian slate with pH ranging from 3.5 to 3.9 (Jotcham

et al 1991), which is lower than optimal for red spruce (4.0–5.5, Blum 1990). Whatever the

mechanism(s) may be, a regional decline in red spruce growth rate and vigor increases the probability

of infestation by T. fuscum and other species known to exploit weakened or stressed hosts.

Mean PRI was significantly lower in attacked trees than in unattacked trees in seven of nine 5-year

periods between 1956 and 2000 (Fig. 1a). This trend persisted when tree age was held constant using

covariance analysis, except that differences were significant in only four of eight 5-year periods (Fig.

1b). The mean 5-year PRIs of unattacked trees ranged from 0.6 to 1.07 cm in the last 40 years, which

corresponds to good (0.82 cm) or acceptable (0.58 cm) vigor classes for second-growth red spruce

(Blum 1990). In contrast, the 5-year PRIs of attacked trees fell below those associated with acceptable

vigor for the period of 1991–1995, and below those associated with inferior vigor (0.38 cm) from

1996–2000 (Fig. 1). Thus it appears that T. fuscum infestation occurred in red spruce that, on

average, were of inferior vigor.

Reasons for the difference in growth rates between attacked and unattacked trees are unknown.

Differences due to site, e.g., soil, exposure, etc., were minimized by the close proximity and size of

trees within pairs. Feeding damage by T. fuscum likely accounts for some of the difference from

1996–2000, but infestation before 1996 is unlikely. Trees attacked by T. fuscum sometime within the

last 1–5 years, were on average 9 years older and had been growing more slowly than unattacked trees

for the last four decades. Age accounted for some but not all of the difference in growth rates. Other

factors possibly responsible for differences in growth rate are genotype and root disease at a stage

where infection was not discernible on cut stumps.

Table 2.—Mean (± S.E.) size, age, and crown condition of 18 pair of red spruce trees in

Point Pleasant Park, Halifax, NS, with signs of Tetropium fuscum infestation (attacked)

and without such signs (unattacked)

Variable Attacked Unattacked P value (paired t-test)

dbh (cm) 27.5 (1.4) 27.3 (1.4) 0.49

height (m) 17.8 (0.5) 17.2 (0.6) 0.31

age (at breast height) 88.2 (4.3) 79.1 (6.3) 0.06

live crown ratio 0.48 (0.03) 0.51 (0.03) 0.59

crown class1 3.8 (0.4) 2.9 (0.1) 0.04

1

crown class assigned using the system described in Table 1.
112 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

0

0.2

0.4

0.6

0.8

1

1.2

1961-65

1966-70

1971-75

1976-80

1981-85

1986-90

1991-95

1996-00

Time (5-yr intervals)

Mean 5-year PRI (cm)

attacked

unattacked

* *

*

*

0

0.2

0.4

0.6

0.8

1

1.2

1906-10

1916-20

1926-30

1936-40

1946-50

1956-60

1966-70

1976-80

1986-90

1996-00

Mean 5-year PAI (cm)

attacked

unattacked

*

*

*

*

* * *

*

In conclusion, our data indicate that red spruce with reduced growth rates and low vigor were more

susceptible to infestation by T. fuscum than faster growing, more vigorous trees. However, our data do

not suggest these trees were weakened to the point that death was imminent before attack by T.

fuscum. Red spruce is a long-lived, shade-tolerant species that can survive more than 100 years of

suppressed growth and still respond to release (Blum 1990). Indeed, the PRI of unattacked trees

increased slightly in the period from 1996–2000, possibly in response to openings in the canopy due

to T. fuscum-related tree mortality (O’Leary 2002). Tetropium fuscum remains a threat to red spruce

and other Picea spp. in North America, because it can infest and kill trees that may be undergoing

periods of stress and suppressed growth due to drought, defoliator outbreaks, or a complex of factors.

Figure 1.—Mean periodic radial increment per 5-year period (PAI) at breast

height of 18 pair of red spruce, Picea rubens Sarg., growing in Point

Pleasant Park, Halifax, NS, that either had signs of attack by Tetropium

fuscum in 2000, or did not. A. Raw means for 19 intervals between 1906

and 2000. B. Least square means from covariance analysis where tree

age was held constant. Asterisks denote significant differences in PAI

between attacked and unattacked trees (ANOVA and COANOVA, P=0.05).

A

B
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 113

Acknowledgments

We thank the Halifax Regional Municipality and staff of Point Pleasant Park and the following

individuals: S. Bishop, D. Brown, G. Cunningham, A. Doane, S. Farrell, G. Gesner, K. Harrison, S.

King, L. Leger, T. Mahendrappa, J. Price, D. Rogers, A. Sampson, J. Simmons, G. Smith, D.

Strongman, T. Walsh, G. Warren, and R. Yerxa. We also thank G. Thurston, H. Piene, and C.

Simpson for comments on an earlier version of the manuscript. Funding for this project was

provided by the Canadian Food Inspection Agency. This work formed part of Karen O’Leary’s

undergraduate thesis in the Faculty of Forestry and Environmental Management, University of New

Brunswick.

References Cited

Blum, B.M. 1990. Picea rubens Sarg. Red Spruce. In: Burns, R.M. and B.H. Honkala (eds.) Silvics

of North America Volume 1. Conifers. USDA Forest Service Agriculture Handbook 654: 250-259.

Cook, E.R. and S.M. Zedacker. 1992. The dendroecology of red spruce decline. In: Eagar, C. and

M.B. Adams (Eds.) Ecology and Decline of Red Spruce in the Eastern United States. SpringerVerlag, New York: 192-231.

D’Eon, S.P., L.P. Magasi, D. Lachance and P. Desrochers. 1994. ARNEWS, Canada’s National

Forest Health Plot Network, Manual on Plot Establishment and Monitoring. (Revised). Natural

Resources Canada, Canadian Forest Service, Petawawa National Forestry Institute, Chalk River,

Ont. Inf. Rep. PI-X-91. 119 p.

Franke-Grosman, H. 1954. Feinde und Krankheiten der Sitkafichte auf norddeutschen Centralbl.

67: 38-48.

Glock, W.S. 1937. Principles and Methods of Tree-Ring Analysis. Carnegie Institute of Washington,

Washington, D.C. 100 pp.

Hornbeck, J.W. and R.B. Smith. 1985. Documentation of red spruce growth decline. Can. J. For.

Res. 15: 1199-1201.

Humble, L.M. and E.A. Allen. 2001. Implications of non-indigenous insect introductions in forest

ecosystems. In: Liebhold, A.M., McManus, M.L., Otvos, I.S., Fosbroke, S.L.C., eds. Proceedings:

Integrated management and dynamics of forest defoliating insects. 15-19 August 1999; Victoria,

BC: USDA Forest Service, Northeastern Research Station, Gen. Tech. Rep. NE-277: 45-55.

Hurley, J.E. and W. MacKay. 2000. Point Pleasant Park crown condition 2000. Unpublished

Report. Natural Resources Canada, Canadian Forest Service, Atlantic Forestry Centre.

Jacobs, K., K.A. Seifert, K.J. Harrison and T. Kirisits. 2003. Identity and phylogenetic

relationships of ophiostomatoid fungi associated with invasive and native Tetropium spp.

(Coleoptera: Cerambycidae) in Atlantic Canada. Can. J. Bot. (in press).

Johnson, A.H. , S.B. McLaughlin, M.B. Adams, E.R. Cook, D.H. DeHayes, C. Eagar, I.J.

Fernandez, D.W. Johnson, R.J. Kohut, V.A. Mohnen, N.S. Nicholas, D.R. Peart, G.A. Schier,

and P.S. White. 1992. In: Eagar, C. and M.B. Adams (Eds.) Ecology and Decline of Red Spruce

in the Eastern United States. Springer-Verlag, New York: 385-411.

Johnson, A.H. and T.G. Siccama. 1983. Acid deposition and forest decline. Environ. Sci. Tech. 17:

294A-305A.

Jotcham, J.R., K.W. Strong and T.K. Marvin. 1991. An Ecological Survey of Point Pleasant Park.

Marbicon Inc. and Maritime Testing Limited.
114 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Juutinen, P. 1953. Ukkoniluri (Dendroctonus micans Kug.) (Col., Scolytidae) okakuusessa (Picea

pungens Engelm.) (Summary: Dendroctonus micans on Picea pungens.) Ebenda 19: 35.

Juutinen, P. 1955. Zur biologie und forstlichen Bedeutung der Ficchtenböcke (Tetropium Kirby) in

Finnland. Acta Entomol. Fenn. 11: 1-112.

Kula, E. and W. Ząbecki. 1997. Lightning-stroken areas as the centres of bark-beetle-infested

patches within spruce stands. Sylwan 8: 89-97. (in Polish with English summary).

Meyer, W.H. 1929. Yields of second-growth spruce and fir in the Northeast. USDA, Washington,

D.C. Technical Bulletin No. 142.

O’Leary, K.L. 2002. Radial growth rate of Picea rubens (Sarg.) and susceptibility to infestation by

Tetropium fuscum (Fabr.) (Coleoptera: Cerambycidae). BScF. Thesis. University of New

Brunswick, Fredericton, NB. 39 pp.

Reineck, G. 1919. Die Insekten der Mark Brandenburg. Coleoptera. Cerambycidae. Deutsche Ent.

Zschr. [German Entomological Journal], Supplement.

SAS 1999-2001. SAS Institute Inc., Cary, N.C.

Schaufuss, C. 1916. Calwer’s Käferbuch. II. Stuttgart.

Schimitschek, E. 1929. Tetropium gabrieli Weise und Tetropium fuscum F. Ein beitrag zu ihrer

Lebensgeschichte und Lebensgeneinsamschaft. Zeitschrift für angewandte Entomologie 15: 229-

334.

Smith, G.A. and L.M. Humble. 2000. The brown spruce longhorn beetle. Exotic Forest Pest

Advisory 5. Natural Resources Canada, Canadian Forest Service. 4 pp.

Smith, G.A. and J.E. Hurley. 2000. First North American record of the palearctic species Tetropium

fuscum (Fabricius) (Coleoptera: Cerambycidae). The Coleopterists Bulletin 54: 540.

Sweeney, J., G. Smith, J.E. Hurley, K. Harrison, P. de Groot, L. Humble and E. Allen. 2001.

The brown spruce longhorn beetle in Halifax: Pest status and preliminary results of research. In:

Fosbroke, S.L.C.; Gottschalk, K.W., eds. Proceedings, U.S. Department of Agriculture interagency

research forum on gypsy moth and other invasive species 2001; January 16-19 2001; Annapolis

MD. Newtown Square, PA: U.S. Department of Agriculture, Forest Service. Northeastern

Research Station. Gen. Tech. Rep. NE-285: 6-10.

Zar, J.H. 1984. Biostatistical Analysis, 2nd Ed. Prentice-Hall, Englewood Cliffs, N.J. p. 95.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 115

Preliminary Results on Predation of Gypsy Moth Egg Masses in Slovakia

Marek Turčáni1, Andrew Liebhold2, Michael McManus3 and Július Novotný1

1

FRI Zvolen, RS Banská Štiavnica, Lesnícka 11, 96923 Banská Štiavnica, e-mail: turcani@lvu.sk

2

USDA Forest Service, Northeastern Research Station, 180 Canfield St., Morgantown,

 WV 26505, e-mail: aliebhold@fs.fed.us

3

USDA Forest Service, Northeastern Research Station, 51 Mill Pond Rd Hamden, CT

 06514-1703, e-mail: mlmcmanus@fs.fed.us

Abstract

Predation of gypsy moth egg masses was studied in Slovakia from 1999 –2002. Predation on

naturally laid egg masses was recorded and linear regression was used to test the hypothesis that

predation follows a type II vs. type III functional response. We also investigated the role of egg mass

predation in gypsy moth population dynamics. The relative contribution of invertebrates vs.

vertebrates as agents of predation on egg masses was estimated using exclosures. During the study,

population densities remained very low and stable. Generally, invertebrata caused 38% and vertebrata

62% of total predation. K-values varied from 0.03 to 0.70 and plots of abundance vs. k-values

suggested that total predation is inversely density dependent, characteristic of a “type II” functional

response. The ultimate role of predation on gypsy moth egg masses remains unclear, however there

are some indications that egg mass predation plays a significant role in the dynamics of gypsy moth

populations in Slovakia.

Introduction

The gypsy moth (Lymantria dispar) is the most serious pest of broadleaved stands (oak stands mainly)

in Slovakia. Outbreaks are repeated in cycles of 6 to 12 years. During the last outbreak of 1992 -

1994, gypsy moth severely damaged more than 18,000 ha of forest land. In stands exhibiting patterns

of long-term oak decline, defoliation can cause increased tree mortality in subsequent years and

therefore, infested stands are often treated with biopesticides, mainly Bacillus thuringiensis. The key

biotic factors influencing population dynamics during the latency phase are not well known in

Slovakia. Conversely, the bioregulation complex of gypsy moth is better understood in the U.S.A.

(Doane and McManus 1981, Elkinton, Liebhold 1990). The goal of this paper is to present results

on a study of gypsy moth egg mass predation during the latency phase. The objectives of this study

were to: Determine the relationship between predation and gypsy moth densities (i.g. identify the

type of functional response); evaluate the role of egg mass predation in gypsy moth population

dynamics; and quantify the relative levels of predation caused by vertebrates vs. invertebrates.

Material and Methods

Survey of Population Density

A series of 12 study plots was established across the outbreak area of gypsy moth in southern Slovakia

(Fig. 1). Surveys of population density were conducted using the Modified Turcek method (MTM)

(Turcani 1998). MTM consists of counting the number of egg masses on 4 points (every point

consists of 30 trees) in the study area. If the average number was over 1.00 egg mass per tree, the

survey was terminated. If it was below 1.00 egg mass per tree, counting continued on another 4

points (together 240 trees). If the population density was below 0.3 egg masses, another 8 points were

taken. The total arrangement consisted of 480 trees. Egg masses were found on trunks from ground

level to the 5 – 8 m.
116 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Figure 1.—Placement of study

plots (• ) in the Slovak Republic

Egg mass predation

Predation on naturally laid egg masses was recorded by inspection of each egg mass found during the

annual survey described above. These inspections were conducted at the end of November (around

the time of first snowfall) and at the beginning of April (when all snow has melted). At the time of

original survey and at each check, the size (length and width) and condition of each egg mass was

recorded (we recorded the proportion of each egg mass that was missing).

The effect of density on predation levels was studied by comparing predation levels at different sites

in different years. Predation was expressed as k-values at each site in each year. Density dependence

was tested by regressing predation vs. log egg mass density. Linear regression was used to test the

hypothesis that predation follows a type II vs. type III functional response (Holling 1965).

The impact of egg mass predation on population growth was evaluated by plotting R (Nt+1/Nt) vs.

k-values from the same year during the entire study period.

The relative contribution of invertebrates vs. vertebrates as agents of predation on egg masses was

estimated using exclosures (Grushecky et al. 1998). These experiments were conducted at Zvolenak

and Pata during the winters of 2000/2001 and 2001/2002. At each site, 150 laboratory reared egg

masses were placed on the stem of individual trees.

Exclosures were placed around 75 of these egg masses. Exclosures consisted of a ~1.5 cm steel mesh

(“hardware cloth”) cage stapled to the bark surface around each egg mass. The proportion of each

mass was recorded in November (around the 1st snowfall) and in the middle of April (prior to the

approximate time of egg hatch). We assumed that the exclosure excluded all vertebrate predators but

did not impede invertebrates and the relative contribution of invertebrate predators will thus be

estimated by the k-values computed from predation of egg masses inside exclosures. K-values for

predation by vertebrates was estimated as the difference between k-values computed from predation

of egg masses without exclosured and k-values computed from predation of egg masses inside

exclosures (Grushecky et al. 1998).

Results

Population Density Survey

Relatively little change in population density occured during the period of 1999 – 2001. The range

of population density varied from 0 to 0.056 egg masses per tree (0 to 28 egg masses/ha). The values

indicate a period of latency on all of the plots. Examples of changes in abundance are provided in

Figures 2, 3 and 4.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 117

0.001

0.01

0.1

1

10

100

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

1991 1992 1993 1995 1996 1997 1998 1999 2000 2001

Figure 3.—Trend of egg masses

at T. Mlyňany

0

0.05

0.1

0.15

0.2

0.25

0.3

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Figure 4.—Trend of egg masses

at Kováčová

Figure 2.—Trend of egg masses

at Bušince.

Table 1.—Predation of naturally laid eggs in study period.

Site Abund k-values Abundance k-values Abundance k-values

1999 1999/2000 2000 2000/2001 2001 2001/2002

Trebišov 1 0.699 0 No egg masses 0 No egg masses

Kurinec 4 0.143 1 0.699 1 0.022

Bušince 2 0.046 0 No egg masses 4 0.097

Pata 6 0.125 26 0.076 1 0.046

Tehla 12 0.131 3 0.456 0 No egg masses

Kováčová 29 0.046 14 0.469 3 0.036

Zvoleňák 13 0.046 19 0.051 0 No egg masses

Vojnice 0 No egg masses 1 0.097 0 No egg masses

T.Mlyňany 12 0.119 4 0.046 0 No egg masses

P. Háje 6 0.097 16 0.056 4 0.027

V. Zalužie 1 0.284 4 0.276 2 0.081

Castá 3 0.187 24 0.081 27 0.051 Egg masses/tree Egg masses/tree Egg masses/tree
118 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

log EM abundance

k - values 

Figure 5.—Comparison of log EM

abundance and k-values at the

same year (n=28, Cc= -0.34).

-1.5

-1

-0.5

0

0.5

1

1.5

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

k-values

log R

Figure 6.—Relationship between log

R (Nt+1/Nt) and k-values (N=28, Cc=

-0.35).

Predation of Naturally Laid Egg Masses

Egg mass predation was generally low and was variable among different sites (Table 1).

Dependence of predation was estimated based on the relationship between k-values and abundance

in the same year. Though there was an apparent negative correlation, this was not statistically

significant (Fig. 5). Nevertherless these data suggest that total predation is inversely density

dependent - “type II” functional response (Holling 1965).

We also found an inverse, but insignificant correlation between predation (K) and change in

population density. These results suggest that predation on egg masses explains some of the variation

in change of population density (Fig. 6).

Determination of the Relative Levels of Predation Caused by Vertebrates vs Invertebrates

Predation in experiments with artificially deployed egg masses was slightly higher than in the case of

naturally laid egg masses. This may have been caused by our deployment of egg masses on transects,

where the abundance of egg masses is higher than normal, and which might attract predatory birds.

Vertebrates caused almost two-thirds of the predation. It is possible, that in several cases, predation

by vertebrates could have occurred in exclosures (by birds with long beaks like Sitta europaea). In that

case, predation caused by vertebrates may have been underestimated in this study.

Discussion

During the length of the study, the quantity of direct damage was low on all sites; k-values only rarely

exceeded 0.4. Until now, the importance of damage on egg masses was not well described. Capek et

al. (1999) published data on the predation of masses during outbreaks when totally damaged egg

masses were found quite often. These data vary from the results of our experiments, in which the

occurrence of totally damaged masses was rare. Randík (1967) also mentioned additional

information about egg mass predation, but no relationship was found between abundance and
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 119

Table 2.—Relative levels of predation in two winters.

Locality Total K % Invertebrata K % Vertebrata K %

Pata 2000/2001 0.102 100 0.046 45 0.057 55

Zvolenak 2000/2001 0.046 100 0.027 59 0.019 41

Pata 2001/2002 0.050 100 0.021 42 0.029 58

Zvolenak 2001/2002 0.132 100 0.030 23 0.102 77

TOTAL 0.330 100 0.124 38 0.206 62

predation. Only frequency of egg mass damage and not the proportion of predation was measured in

these experiments.

Turček (1949) observed the following bird species as feeding on gypsy moth egg masses: Certhia familiaris,

Sitta europaea, Parus major, Parus caeruleus, Parus major and Aegithalos caudatus. During our experiments,

we did not make direct observations of the bird species that were active in the study area.

Various aspects of egg mass predation (e.g., dependence between size of masses and predation;

location of masses on trees; and predation and dependence between abundance and predation) were

studied by Higasiura (1989). Abundance during his experiments varied between 27 to 230 masses per

ha (0.05 to 0.5 EM/T). Percentage of predation varied with abundance and among years. Predation

of masses by birds was not usually closely related with abundance. However, when the range of

abundances was high, he found a significant inverse correlation dependence between abundance and

predation. Higasiura (1980) reported that when abundance varied from 6 to 231 masses per 1 ha

(0.01 to 0.5 masses per 1 tree), the predation by birds was almost density independent, but an inverse

density dependent trend was observed in 1 year. As a whole, the correlation between egg mass density

and percent predation was not apparent. Comparison of abundance and k-values during our

experiment suggested an inversely density dependent relationship, but this correlation was not

significant.

These results indicate that bird populations are not tightly linked ecologically to populations of gypsy

moth and feeding on egg masses is mostly accidental. Predation during individual years may depend

on the availability of alternate sources of food to birds and not on the abundance of gypsy moths. An

important fact during our experiments was that we used naturally laid eggs except in the vertebratesinvertebrates experiments. In this case it was possible to exclude effect of bird concentrations on areas

containing higher egg mass densities.

However, it may be that predation of egg masses is not insignificant in the population dynamics of

gypsy moth in Slovakia during the latency phase. Despite the fact that the correlation between log R

and k-values was not significant, it is still possible that predation on egg masses plays a relatively

important role in gypsy moth population dynamics in Slovakia. The narrow range of egg mass

densities encountered along with the sampling methods that were utilized in this study may have

limited our ability to detect these relationships.

Conclusions

• Population densities were very low and relatively stable during the study period.

• K-values varied from 0.03 to 0.70 and total predation was slightly inversely density dependent -

“type II” of functional response.

• The ultimate role of predation on gypsy moth egg masses is not clear, however there are some

indications that predation of egg masses plays some role in the dynamics of gypsy moth

populations in Slovakia.

• These experiments indicate that invertebrates caused 38% and vertebrates 62% of egg mass

predation.
120 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

References Cited

Capek, M., Kristin, A., Novotny, J., Findo, S., Hesko, J., Patocka, J. 1999. Feinde der

Eichenschadlinge. In: Patocka, J., Kristin, A., Kulfan, J., Zach, P. (Eds.) Die Eichenschadlinge und

ihre Feinde. p. 277-347.

Doane, C. C., McManus, M. L. (eds.) 1981. The gypsy moth: Research toward integrated pest

management. USDA For. Serv. Sci. Educ. Ag. Technical Bull. 1584, Washington, D. C. 1981, 757

pp.

Grushecky, S.T., Liebhold, A.M., Greer, R., Smith, R.L. 1998. Does forest thinning affect

predation on gypsy moth (Lepidoptera: Lymantriidae) larvae and pupae? Environ. Entomolo.

27:268-276.

Holling, C.S. 1965. The functional response of predators to prey density and its role in mimicry

and population regulaton. Mem. Entomol. Soc. Ca. 45:1-60.

Higasiura, Y. 1980. Analysis of factors affecting bird predation on gypsy moth egg masses by using

Holling ́s disc-equation. Res. Popul. Ecol. 22: 147-162

Higasiura, Y. 1989. Survival of eggs in the gypsy moth Lymantria dispar. L. predation by birds. Jour.

Animal Ecol. 58: 403-412.

Elkinton, J.S. and Liebhold, A.M. 1990. Population dynamics of gypsy moth in North America.

Ann. Rev. Entomol. 35: 571-596

Randik, A. 1967. [Contribution to conservation of birds in areas of occurence of gypsy moth

(Lymantria dispar L.) in the southern Slovakia]. In:Prace a studie ceskoslovenskej ochrany prirody,

Bratislava. 1(2): 1-89.

Turcani, M. 1998. [Estimation of gypsy moth (Lymantria dispar L.) abundance changes in different

parts of outbreak area in Slovakia during the period 1990 - 1997 by using modified Turcek

method]. Vedecke prace LVU Zvolen n. 42, Priroda, p. 129 - 155.

Turcek, J. F. 1949. [About bird populations in deciduous forests during outbreak of gypsy moth].

Zpravy Statnich vyzkumnich ustavu lesnickych CSR. p. 108 – 131.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 121

Introduction

The present study was initiated in 2001 in the oak forests from Trotuș valley (Forest District Căiucţi

– Bacău, Romania) which were heavily infested by oak sawflies Apethymus abdominalis Lep.

(Hymenoptera: Tenthredinidae), in order to understand better the role of soil-inhabitating predators

in population regulation of this pest.

A serious outbreak of this defoliator was recorded during the years 1999-2000 and thus a series of

treatments with the chitin inhibitors Dimilin and Rimon were applied against larval populations in

those forests. Subsequently, after the year 2000, we observed an increase in populations of its natural

enemies, from egg-larval parasitoids to eonimphal predators, which gradually subdued the outbreak.

A series of soil inhabitating predators, namely from the families Carabidae (genera Abax, Carabus,

Harpalus, Pterostichus etc.) and Staphilinidae (Staphilinius, Optionus, Philontus etc.), as well as red

mites (Stigmotrombidiidae) and forest red ants were recorded.

Materials and Methods

Soil fauna was collected using a series of Barber traps. Each series consisted in 12 traps (consisting of

a 10 cm diameter, 250ml cup). Nine series of traps were placed in three plots within the Forest

District Căiucţi-Bacău: Păltinata Forest (3), Heltiu Forest (5) and Cornăţel Forest (1). During 2001,

contents of the Barber traps were collected monthly beginning on the 15th of April and continuing

until the 19th of October (six collecting periods).

The level of defoliation of oak trees in the forests under study was estimated by sampling branches

and by estimating the number of eonimphae in the soil around trees. We also recorded the number of

other defoliators that are found characteristically in oak forests.

Results

In the spring of 2000 the level of defoliation of oaks by larvae of Apethymus abdominalis in the study

areas was estimated to be 97% in the Heltiu Forest, 15% in the Păltinata Forest and 5% in the

Cornăţel Forest. The numbers of eonimphae in the soil was estimated to be 4 specimens/m2

 in

Păltinata and 20 specimens/m2 in Heltiu. Minor defoliation by other forest pests including Tortrix

viridana, Operophtera brumata, Erannis delfoliaria, Orthosia sp.of caterpillars was also noted in all

areas, but especially in the Cornăţel Forest.

As a consequence of the treatments applied in 1999-2000, the larval populations in the spring of

2001 were at extremely low levels (1-2%), meanwhile the number of eonimphae in the soil was high

(maximum 40 specimens/m2

 in Heltiu Forest). However, the caterpillar complex caused an estimated

defoliation of 50% in the Cornăţel Forest.

The abundance of available larvae, especially those in the latest instar (L6), and sawfly econimphae

induced an abundance of select invertebrate predators in the soil. The most numerous were over 30

The Role of Selected Soil Fauna as Predators of

Apethymus abdominalis Lep. (Hymenoptera, Tenthredinidae)

in Oak Forests in the District Căiuţi, Romania

C. Ciornei1, N. Popa2, L. Ciucă3 and C. Rang4

1

Forest Reasearch Station Hemeiuși – Bacău, Romania, e-mail: icasbc@mic.ro 2

Forest Direction Bacău, Romania 3

Natural Sciences Museum of Bacău, Romania

4

University of Bacău, Romania
122 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

species, of carabids such as Abax ater, Carabus coriaceus, C. granulatus, Harpalus pubescens, Pterostichus

oblongopunctatus, and over 10 species of staphilinids such as Staphilinius olens, Philontus chalceus,

Quedius sp.). In the forests Păltinata and Heltiu, there was an abundance of red mites (Acarina) from

the genus Eutrombidium (Stigmotrombidiidae) during the spring of 2001.

In the Cornăţel Forest we observed intensive activity of forest red ants (Formica ruffa) (1751

specimens/series of 12 traps) followed by carabids (only Harpalus pubescens registered 195 specimens/

series, other carabid larvae (698 specimens/series) and staphilinids (46 specimens/series). Most

predator species were active during the months of April-May; however an omnivorous forest red ant

was active during all vegetation periods.

The most heavily infested area was the Heltiu Forest, where two successive treatments were applied in

1999 and in 2000. Our results confirmed that there was a decline in a quantitative diminution of the

number of predators in 2001 as compared to the previous years, however the species diversity was

relatively unaffected-35 species in Heltiu Forest, 30 species in Forest Păltinata and 28 species in

Forest Cornăţel.

References Cited

Ciornei, C.; Mihalache, GH. 1999. Apethymus abdominalis (Hym., Tenthredinidae) a new pest of

the oak forests in Romania. Proc of the Second Workshop of IUFRO WP: 7.03.10, April 20-23,

Sion-Chateauneuf, Switzerland WSL Birmensdorf: 268-270.

Ciornei, C.; Popa, N. 2000. Control experiments of pest Apethymus abdominalis Lep. (Hym.,

Tenthredinidae) in oak forests from Romania. Proc. Of the IUFRO WP 7.03.10. Workshop, Sept

24-28, Bușteni, Romania, 17-21.

Ciornei, C.; Popa, N., Rang, C., Ciucă, L. 2001. The influence of natural limitative factors an the

outbreak of Apethymus abdominalis Lep. (Hym., Tenthredinidae) from oak forest Heltiu –

Romania, Fourth Workshop of the IUFRO, WP 7.03.10, Sept. 17-20, Prague, Czeh Republic, 59-

61.

Thiele, H-U. 1977. Carabid beetles in their environment. A study on habitat selection by adaptation

in physiology and behavior, Springer-Verlag Berlin-Heilderberg-New York, 362 pp.

Titovsek, K. 1992. Gradacija hrastasih grizlic (Apethymus abdominalis Lep. Un A. braccatus Gmelin)

v krakovsken gozdei. Gozd. Vest, Liubljana, 50, 9 :386-393.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 123

Black locust (Robinia pseudoacacia) is a significant plantation tree in Hungary, which was introduced

to Hungary in the mid 18th century and now occupies more than 21.6% of the forested area (nearly

370 thousand hectares). Two species of leaf miners, Parectopa robiniella Clemens 1859 and

Phyllonorycter robiniella Clemens 1859 have invaded Hungary in the last two decades. Both species

have become widespread and abundant on black locust throughout the country and serious

infestations cause early leaf abscission on affected trees. No detailed study on parasitoids associated

with these species have been conducted; this abstract reports results from the first year of the study on

their parasitoid communities.

The work was carried out at two locations in 2001; Gödöllő is ca. 30 km NE-E of Budapest and

Visonta is ca. 80 km in the same direction. Black locust is an abundant tree species at both sites and

the stands that were sampled at both locations were relatively young (12-15 years). We deliberately

chose younger stands because on younger trees (up to 6-8 m in height), the entire crown can be

sampled using a long stalk brunch cutter. This way the sampling can be more representative than

sampling only lower branches of larger trees. Beginning in early June, both sites were visited at 3-5

days intervals in order to determine the optimal time for sampling.

A significant difference was found in development of the two species. The 1st generation of Parectopa

completed its development later than Phyllonorycter. In case of the 2nd generation, the difference was

even larger, therefore the two species had to be sampled separately. At both sites for all sampled

generations, 15 ca. 60 cm long branches were selected at random and were cut. Only the mines of the

sampled generations were counted, whereas the old mines and the very young mines (under 10 mm)

were neglected. We counted and recorded the following characteristics:

- number of leaves on sample branches

- number of leaflets by leaves

- intact leaflets

- leaflets with Phyllonorycter mines and leaflets with Parectopa mines

- leaflets with mines of both species

- number of larvae in each mine

About 500-600 mined leaflets were collected randomly during each sampling period. The first 300

mined leaflets containing either final instar larvae or pupae of the host were put into plastic tubes for

individual rearing. The number of mines/leaflet and number of larvae in mines were counted in

advance. If the leaflet contained mines of two species, the larva of the “secondary” species were

removed from the mines (i.e. in case of Phyllonorycter sampling, larvae of Parectopa were removed

from mines and vice versa). The rearing tubes were checked weekly and the emerged parasitoids were

put into vials together with labels. The dead specimens were kept dry, while those that were still alive

were placed into 70% alcohol. The braconids were identified by Dr. Jenö Papp (Natural History

Museum, Budapest) and the chalcids were identified by Dr. George Melika (Systematic Parasitoid

Laboratory, Kőszeg).

The first mines of Parectopa appeared ca. 2-3 days later than first mines of Phyllonorycter. While

Phyllonorycter produced three generations Parectopa produced only two generations. Parectopa mines

nearly always contain a single larva, whereas Phyllonorycter mines often contain more than one larva

Parasitoid Communities of Two Invading Leafminers of Black Locust

in Hungary: First Year Results

György Csóka1, Anikó Hirka1 and George Melika 2

1

Forest Research Institute, Department of Forest Protection, Mátrafüred, Hungary

2

Systematic Parasitoid Laboratory, Kőszeg, Hungary
124 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

(as many as five) In this case it is still not clear whether they originate from one female or from several

females whose eggs are laid close to each other.

The most striking result of the rearing experiment is that hardly any parasitoids were reared from

Parcetopa. The highest attack rate (Visonta, first generation) was only 1%. The attack rates by

parasitoids were much higher for Phyllonorycter. The very low attack rate that we recorded for the

third generation at both sites is due to the fact that the parasitoids that developed in the third

generation of the host entered diapause along with their hosts. The most significant parasitoid of

Phyllonorycter at both sites was the braconid Pholetesor nanus. It was responsible for 54-76% of the

total parasitism. This species is known to attack a range of native Phyllonorycter leaf miners in Europe.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 125

Introduction

Trap efficacy in capturing economically important forest Coleoptera was measured in

field trials comparing the Intercept Panel Trap (INT PT) with the Multi-Funnel

Trap. The INT PT was designed to provide a better option for the monitoring of

forest Coleoptera. The trap is made of corrugated plastic and is very robust under

rigorous field conditions, but still lightweight, easy to carry, weather- and waterproof,

and easy to install. The trap disassembles rapidly and stores flat, therefore requiring

less storage space than Funnel Traps. The INT PT also costs significantly less than

the Funnel Trap.

Methods and Materials

Field trials were conducted on five sites within the United States: OR, NC, MN, WI,

and NY. In OR, NC, MN, and NY three types of traps were tested: INT PT treated

with Rain-X (INT PT-R), INT PT untreated (INT PT), and Multi-Funnel Trap

(Phero Tech, Inc.). The traps were baited with three prototype lures: (1) standard lure (alpha-pinene

(ap), ipsdienol(id), ipsenol (ie)), (2) turpentine lure (turpentine, id, ie), and (3) ethanol lure (ethanol,

ap, id, ie). Five combinations of trap and lure determined the treatments: (A) INT PT-R + lure 1, (B)

Funnel trap + lure 1, (C) INT PT + lure 1, (D) INT PT-R + lure 2, and (E) INT PT-R + lure 3. In

WI, INT PT and Funnel Traps were both baited with lure 1. The wet-cup method was used, and

captured insects were collected every 10 days.

Results

Data from captures in individual states are provided in the attached figures. The INT PT performed

equal to or better than the Multi-Funnel Trap for Cerambycids and Scolytids. Captures of Buprestids

were lower in the INT PT than in the Funnel Trap. The INT PT captured more bark beetles and

consistently fewer predators than the Funnel Trap. The turpentine lure (2) caught equal or fewer

numbers of beetles than the standard lure (1); the ethanol lure (3) caught more bark beetles than the

standard lure (1).

Discussion

The Intercept Panel Trap is an effective tool for monitoring Cerambycids, as well as bark beetles,

Buprestids, and other forest Coleoptera. It also captures fewer beneficial insects. The INT PT

outperformed Phero Tech’s Multi-Funnel Trap for most tested insect species. Higher beetle captures

and increased detection capability in a less expensive trap equates to greater efficiency of forest pest

monitoring programs. The Intercept Panel Trap is now commercially available.

InterceptTM Panel Trap (INT PT) Effective in Management of

Forest Coleoptera

D. Czokajlo1, J. McLaughlin1, L.I. Abu Ayyash1, S. Teale2, J. Wickham2, J. Warren3,

R. Hoffman1

, B. Aukema4, K. Raffa4 and P. Kirsch1

1

IPM Tech, Inc., 4134 N. Vancouver Ave. #105, Portland, OR, USA 97217, tel. (503)288-2493,

 fax. (503)288-1887, e-mail: ipmtech@ipmtech.com, web: www.ipmtech.com

2

SUNY ESF, Syracuse, NY, USA,

3

Cloquet Forestry Center, Cloquet, MN, USA,

4

University of Wisconsin, Madison, WI, USA
126 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Comparative Trapping of Forest Coleoptera, 

INT PT and Multi-Funnel Trap, 

Mirror Lake State Park, WI, Summer 2002

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Summer 2002

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Comparative Trapping of Forest Coleoptera, INT PT and Multi-Funnel 

Trap, Forest Grove, OR, Summer 2002
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 127

Abstract

In I. typographus, the development of immature stages can proceed at various day lengths, however

ambient temperature must reach at least 5oC. In central Europe, the adults fly and reproduce only

when temperatures are above 14oC and photoperiods are in excess of 15 hrs. of light. When the last

instar larvae, pupae, or adults develop at a short photoperiod (SD, 12:12 hrs. in our experiments)

and at a temperature of less than 23oC, only diapausing adults are produced. Imaginal diapause,

which is characterized by a reproductive block, reduction of flight muscles, and behavioral changes, is

a crucial adjustment to seasonal changes. In Central Europe, bark beetles terminate egg laying in

August, just in time so that the already present immature stages can complete their development into

adults before winter ensues. The gonads of diapausing adults may slowly develop at 5oC but

reproduction does not resume even when the adults are transferred to conditions that normally favor

development (20oC and 18 hr day length). After a couple of weeks at 5oC however, the adults initiate

reproduction when they are transferred to a regime of 20oC and 18 hr day length. Long exposures at

5oC render the adults insensitive to photoperiod and they reproduce efficiently under conditions (12

hr day length and 20oC) that would cause the non-chilled beetles to induce or maintain diapause.

Under field conditions, diapause is terminated sometime in January and reproduction is halted

thereafter due only to low temperature. Diapause can be induced only after one reproductive cycle

and in the new bark beetle generation.

Imaginal Diapause in the Bark Beetle, Ips typographus

Petr. Doležal and František Sehnal

Academy of Sciences and Faculty of Biological Sciences, University of South Bohemia,

 Branisovska 31,370 05 Ceské Budejovice, Czech Republic
128 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Xylobios: Patterns, Roles and Determinants of Saproxylic Diversity

in Belgian Deciduous Forests

Philippe Fayt1, Etienne Branquart1, Marc Dufrene1, Jean-Marc Henin2,

Christophe Pontegnie3 and Veerle Versteirt4

1

Research Centre of Nature, Forests and Wood

2

Gembloux Agricultural University

3

Catholic University of Louvain

4

Royal Belgian Institute of Natural Sciences

Abstract

The XYLOBIOS project aims to study patterns, roles and determinants of saproxylic diversity (i.e.,

species richness and abundance of organisms which are dependent upon the dead or dying wood of

moribund or dead trees, or upon the presence of other saproxylics) found in Belgian beech Fagus

sylvatica and oak Quercus spp. forests. The project originates from recent international

recommendations to retard loss of species and link biodiversity with ecosystem functioning. Main

objectives, study sites and sampling methods are briefly described.

Key words: beech; biodiversity; ecosystem functioning; monitoring; oak; saproxylic organism;

woody debris

Introduction

Saproxylic organisms (1) account for a significant part of forest biodiversity (20-25% of all forestdwelling species) (Siitonen 2001), (2) speed up wood decomposition and recycle large amount of

nutrients through multitrophic interactions (Harmon et al. 1986, Edmonds and Eglitis 1989), (3)

are threatened over much of their range, as a direct consequence of large-scale intensive forest

management practices and the loss of primeval growth conditions (Speight 1989), and (4) suffer

from a bad reputation world-wide in the northern hemisphere, based mainly on the tree damage and

economic losses a few species may cause once their population increases above some abundance

threshold (Vité 1989). Ultimately, one of the main arguments for maintaining dead wood habitats

and preserving saproxylic assemblages is that losses of diversity may impair processes required for the

long-term functioning of the ecosystems (Bengtsson et al. 2000), which, in turn, is expected to

increase societal costs in a non-linear manner (Tilman 2000). This emphasises a need for a better

understanding of interrelationships between biological diversity and forest management.

Objectives

XYLOBIOS is a four-year research project started in Belgium in 2001 to address simultaneously and

link both ecological and economical issues raised by forest management of beech Fagus sylvatica and

oak Quercus spp. forests. Its goals are:

- clarify the national distribution of selected saproxylic families and species, indicators of

microhabitats and processes found in natural and extensively managed deciduous forests

- identify the multi-scale determinants of their diversity

- relate saproxylic diversity and site factors with tree mortality and soil properties

- study co-variation in species richness among different saproxylic taxa

Material and Methods

Studied taxa: insects (Coleoptera, Diptera), fungi (Polyporale, Corticiale) and cavity-nesting birds

Monitoring: enquiries sent to naturalists, biogeographical databases
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 129



Figure 1.—Study sites

Figure 2.—Grid-based nested plots

Field inventories:

Study sites: 22 sites (10 beech/12 oak stands = 11 site pairs), distributed

over 4 biogeographic areas (Fig. 1). A pair: sites with similar plant

composition, soil properties and abiotic factors (altitude, climate) but with

contrasting management histories and supply of woody debris

Insects: (i) a 0.8 ha circular study plot per site, in which 8 flight-window traps,

8 trunk-window traps1

, 1 Malaise trap, and 3 stump eclectors, and (ii)

bark sampling and gallery eclectors on recently logged beech trees (1

 if

standing dead trees available)

Fungi: hand-collected within the 0.8 ha study plots

Birds: point counts or transects within circular plots of 20 ha, centred on the 0.8 ha plots

Soil: 3 sample cores in the Ah layer (0-20 cm) per 0.8 ha study plot

Other habitat variables: (i) nested circular sample plots (0.006, 0.05 and 0.1 ha) located on a grid

network of 50 x 50 m covering the study sites to gain information

on small-scale structural heterogeneity, and (ii) regional

circular sample plots (1,256 ha, centred on the 0.8 ha

study plots), to measure modern landscape

characteristics and its historical changes (Fig. 2)

Acknowledgments

This project is financially supported by the Belgian

Federal Office for Scientific, Technical and Cultural

affairs (OSTC). The research team of Prof. Laurent Bock,

University of Gembloux, is kindly acknowledged for

providing help in soil analyses.

References Cited

Bengtsson J., S.G. Nilsson, A. Franc, and P. Menozzi. 2000. Biodiversity, disturbances, ecosystem

function and management of European forests. For. Ecol. Manage. 132: 39-50.

Edmonds, R.L., and A. Eglitis. 1989. The role of the Douglas-fir beetle and wood borers in the

decomposition of and nutrient release from Douglas-fir logs. Can. J. For. Res. 19: 853-859.

Harmon M.E., J.F. Franklin, F.J. Swanson, P. Sollins, S.V. Gregory, J.D. Lattin, N.H. Anderson,

S.P. Cline, N.G. Aumen, J.R. Sedell, G.W. Lienkaemper, K. Cromack, JR., and K.W.

Cummins. 1986. Ecology of coarse woody debris in temperate ecosystems. Adv. Ecol. Res. 15:

133-302.

Siitonen, J. 2001. Forest management, coarse woody debris and saproxylic organisms:

Fennoscandian boreal forests as an example. Ecol. Bull. 49: 11-41.

Speight, M.C.D. 1989. Saproxylic invertebrates and their conservation. Council of Europe,

Strasbourg.

Tilman, D. 2000. Causes, consequences and ethics of biodiversity. Nature 405: 208-211.

Vité, J.P. 1989. The European struggle to control Ips typographus – past, present and future. Hol.

Ecol. 12: 520-525.
130 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

Most woodwasps (Siricidae) are symbiotically associated with the specific fungus, Amylostereum spp.

Female adults inoculate the fungus during their oviposition in sapwood of the host trees (Morgan

1968). Woodwasp larvae can digest sapwood with low nutritional quality with the aid of symbiosis

(Kukor and Martin 1983). In the earlier study, we clarified that a woodwasp with no fungal

symbionts, Xeris spectrum can utilize the fungal symbionts of other woodwasp species without

possessing any symbiotic fungi of its own (Fukuda and Hijii 1997). Moreover, the larvae of funguscarrying woodwasp species cannot develop on living trees. The female adults oviposit selectively on

fresh trees that are presumed to be suitable for fungus propagation, because the conditions of the

wood at the time of oviposition affect propagation of the fungus (Fukuda 2002). Whether funguscarrying woodwasps can develop using no maternal symbiotic fungus or not has never been studied.

Thus, I conducted fungus-isolation and oviposition experiments to evaluate the preference and

performance of U. japonicus on fungus-inoculated trees.

Experiments were conducted from 1999 to 2001. In July 1999, the first year, new female adults of U.

japonicus were allowed to oviposit on living trees of Cryptomeria japonica (oviposited trees). In

October, the symbiotic fungus of U. japonicus was artificially inoculated on living trees of C. japonica

(inoculated trees). In November, oviposited trees, inoculated trees and control (not oviposited and

not inoculated) trees were felled and a part of the inoculated trees were bucked to 2 m. In July 2000,

the second year, new female adults were allowed to oviposit on each tree. At the same time, fungi

were isolated from both oviposited and inoculated trees. In 2001, the third year, I counted the

number of new adults that emerged from each tree where oviposition occurred in the 2nd year, and I

also counted oviposition holes on each tree.

The inoculated symbiotic fungus propagated on both oviposited trees and inoculated trees 8 months

after tree-felling, oviposition period of the next year. Moreover, on inoculated trees, especially on

bucked trees, the symbiotic fungus was distributed widely in the wood. The oviposition by U.

japonicus was higher on oviposited trees and inoculated trees than on control trees; moreover, the

oviposition was higher on inoculated trees than on oviposited trees. On inoculated trees, many

oviposition holes were observed near vertical lines from inoculated positions, where the symbiotic

fungus would propagate vigorously. Next generation adults emerged from inoculated trees, whereas

no adults emerged from oviposited and control trees. The number of emerged adults was especially

high on bucked trees. From these results, I demonstrated that a fungus-carrying woodwasp species,

U. japonicus, can reproduce using no maternal symbiotic fungus. These results indicate that both X.

spectrum, a woodwasp species that has no maternal symbiont, and U. japonicus a fungus-carrying

woodwasp species, can utilize the Amylostereum fungi which had already propagated in the wood.

This information is important for clarifying the coevolution between woodwasps and Amylostereum

fungi.

Key Words: Amylostereum fungus, fungus-isolation, oviposition preference, survival rate, Urocerus

japonicus

Reproduction of a Woodwasp, Urocerus japonicus

(Hymenoptera: Siricidae) Using No Maternal Symbiotic Fungus

Hideshi Fukuda

Unit of Environmental Systems, Faculty of Social and Informational Sciences,

 Nihon Fukushi University Higashiehaemi-cho, Handa, Aichi Japan
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 131

References Cited

Fukuda, H. 2000. Trunk sapwood utilization by woodwasps. Japanese Journal of Ecology 52:75-80.

Fukuda H. and Hijii N. 1997. Reproductive strategy of a woodwasp with no fungal symbionts,

Xeris spectrum (Hymenoptera: Siricidae). Oecologia 112:551-556.

Kukor J.J. and Martin M.M. 1983. Acquisition of digestive enzymes by siricid woodwasps from

their fungal symbiont. Science 220:1161-1163.

Morgan F.D. 1968. Bionomics of Siricidae. Annual Review of Entomology 13: 239-256.
132 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

On December 26, 1999, Switzerland was struck by the most severe storm in the country’s history. An

extensive dataset from the Canton Berne allowed us to test the hypothesis that in regions where

windthrown wood was cleared a) the intensity of the first Ips typographus-infestation on standing trees

after the storm depends on the distance from windthrow areas and b) the intensity of the first

infestation depends on the temperature differential at different altitudes. Both hypotheses have been

verified, however our results suggest that the first infestation of standing trees after the storm is not

caused by the emigration of bark beetles from adjacent windthrow areas.

Material and Methods

Windthrow areas (>0.5 ha) were digitized from orthophotos. Additionally, the forest managers

recorded the center-coordinate of scattered windthrow groups with the corresponding amount of

wood. The clearing of windthrow areas and the removal of scattered windthrow trees was completed

approximately one year after the storm. Furthermore, the forest managers recorded the infestation

spots on standing trees with the corresponding amount of spruce. The trees were harvested in the

same year. For horizontal analysis we classified the data in different distance rings around the

windthrow areas. For vertical analysis we classified the data in different altitudinal belts. For each

distance class and altitudinal belt we calculated the forest area, the volume of infested standing

spruces, and the volume of scattered windthrown wood. For the altitudinal belts, we calculated also

the total standing volume of Norway spruce from data of the Swiss National Forest Inventory.

Results and Discussion

We found a dramatic decrease in the proportion of beetle-infested spruce trees per forest area with

increasing distance from windthrow areas (Fig. 1). This was also found by Wichmann and Raven

(2001). These authors concluded that the spatial pattern of bark beetle infestation of standing spruce

after heavy storm damage reflects the spread of I. typographus emigrating from the windthrow areas.

Our study indicates, however, that the first infestation of standing trees after heavy storm damages

may not reflect the spread of I. typographus. We found a strong positive relationship between the

Spatial Patterns of First Spruce Bark Beetle (Ips typographus L.)

Infestation of Standing Norway Spruce (Picea abies [L.] Karst.)

After Heavy Storm Damage in Switzerland

R. Gall and A. Heimgartner

Swiss Federal Research Institute WSL, Birmensdorf, Switzerland

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9

10

 beetle-infested standing spruce

 scattered windthrown wood

distance from windthrown areas (m)

beetle-infested standing spruce (m3/ha)

0

2

4

6

8

10

12

14

16

18

20

22

scattered windthrown wood (m3/ha)

Figure 1.—Densities of beetle-infested

standing spruce () and scattered

windthrown wood () in relation to the

distance from windthrow areas.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 133

volume of scattered windthrown trees and the volume of bark beetle infested spruce (r2= 0.996,

p< 0.0001, c.f. Fig. 1). Considerable infestation was found also at greater distances (> 500 m) from

the windthrow areas (Fig. 2). We hypothesize that the volume of scattered windthrown wood might

be an indicator of reduced host-tree resistance of the residual stands after heavy storm damage. This

means that the first infestation of standing spruce occurred mainly in weakened trees.

In Switzerland, an altitudinal increase of 100 m corresponds to an average temperature decrease of

0.65°C. Therefore, the gradual decrease in beetle-infested spruce from the lower elevations up to

higher altitudes (Fig. 3) stresses the importance of temperature on the velocity of spruce bark beetle

development; this was reported also by Wermelinger and Seifert (1998) but under laboratory

conditions.

References Cited

Wermelinger, B. and M. Seifert. 1998. Analysis of the temperature dependent development of

spruce bark beetle Ips typographus (L.) (Col., Scolytidae). J. Appl. Ent. 122: 185-191.

Wichmann, L. and H.P. Raven. 2001. The spread of Ips typographus (L.) (Coleoptera, Scolytidae)

attacks following heavy windthrow in Denmark, analysed using GIS. For. Ecol. Manag. 148: 31-39.

Figure 2.—Representative part of the

Canton Berne with forest area (light grey),

windthrow areas (dark grey), scattered

windthrow groups () and spots of

infestation () for the year 2001.

Figure 3.—Beetle-infested spruce

per total standing volume of spruce

in relation to altitudinal belts (meters

above sea level).

600-700 700-800 800-900 900-1000 1000-1100 1100-1200 1200-1300 1300-1400 1400-1500 1500-1600 1600-1700 1700-1800 1800-1900

0

2

4

6

8

10

12

14

16

18

20

22

infested standing wood (m3) per total standing volume of spruce (m3

)

altitudinal belt (meters a.s.l)
134 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Introduction

Xylophagous scolytids (Ambrosia beetles) have long been known to prefer fallen or seriously

weakened trees and stumps. They are attracted to this host material by ethanol produced by the

fermenting phloem and sapwood. However, these insects have begun aggressively attacking living

beeches in Southern Belgium, raising the issue of a possible shift towards primarity. More than 1.3

million m3 have been attacked in 2001 (Huart and Rondeux 2001). Strikingly, similar occurrences of

ambrosia beetles attacking living broadleaf trees have been observed worldwide recently. A series of

experiments have been carried out since December 2000 to answer a series of rather basic but

essential questions : what is the beetles’ phenology ? Do they have two generations a year ? What are

the patterns of emergence for both species ? How far from an outbreak focus do they represent a

threat to other stands?

Material and Methods

Phenology

Four baited Theyson traps (distance between traps : 50 m) were placed in four attacked sites in the

Ardennes. Catches were counted and identified once each week from the begining to the end of the

flight period for both species.

Patterns of Emergence

15 individual and 23 collective emergence traps were placed on infested trees at the end of the 2001

flight period. Catches were counted and identified once each week from 12 July to 3 October for

individual traps, and from 1 August to 1 October for collective traps.

Life Cycle and Parental Care

In 2001, galleries of the two species were opened periodically during the attack period, from early

April to the end of June, in order to observe the behaviour of adults inside, check on the

development of progeny, and to determine whether or not a second generation exists.

Dispersal of Trypodendron spp. from Beech Stands to Open Areas

In Recogne and Witry, three and four baited (ethanol+lineatin) traps were placed in an open area at

50, 100 and 200 m, and at 50, 100, 200, and 400 m

from the edge of an infested beech stand. Catches

were counted and identified once each week during

the flight period - from 2 April to 23 May, 2002 for

Recogne, and from 24 April to 23 May for Witry.

Results

Phenology

The flight period for T. signatum was about one

month later than for T. domesticum (Fig. 1 and

Trypodendron domesticum and Trypodendron signatum:

Two Scolytid Species Involved in Beech Decline in Belgium

B. Gaubicher1, M. De Proft1 and J.-C. Gregoire2,3

1

Department of Phytopharmacy, Agricultural Research Center of Gembloux, Belgium

2

Laboratoire de Biologie animale et cellulaire, Université Libre de Bruxelles, Belgium

3

Fonds National Belge de la Recherche Scientifique, Bruxelles

0

20

40

60

80

100

120

140

160

180

2/5/2002

2/12/20022/19/20022/26/2002

3/5/2002

3/12/20023/19/20023/26/2002

4/2/20024/9/2002

4/16/20024/23/20024/30/2002

5/7/2002

5/14/20025/21/20025/28/2002

6/4/2002

6/11/20026/18/20026/25/2002

7/2/2002

Date

Mean catches

Anlier

Croix-scaille

Gedinne

Libin

Figure 1.—Phrenology of T. signatum.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 135

Fig. 2). The earlier flight of T. domesticum might

perhaps be connected to the fact that it

overwinters in the galleries where it might be able

to feed throughout the winter on fungi.

Patterns of Emergence

We observed that most young adults of T.

signatum emerged from their galleries at the end

of the summer. They probably spent the winter in

the litter, at which time they were not attracted to

pheromone traps. T. domesticum did not emerge

from their galleries before spring. They

overwintered in the galleries.

Life Cycle and Parental Care

For both species, parental care (essentially cleaning of the gallery by the female) is continuous until

pupation is completed. We have observed one male at the entrance of each gallery. The exact role of

the male during this period is still not clear; males may be guarding the female or may help to clean

the gallery. Egg laying occurred in one single period, after which the larvae developed and pupated.

There was thus no sister generation within any single gallery.

Dispersal of Trypodendron spp. from Beech Stands to Open Areas

The two Trypodendron species are obviously able to

disperse beyond beech stands at least as far as 400

meters (Fig. 3 and Fig. 4). This suggests that

dispersal could occur between beech stands during

outbreaks. Lines of baited traps placed at the edge of

attacked stands might possibly prevent or reduce

these movements.

Open Questions

T domesticum and T. signatum diverge in many

respects, for example in their reproductive biologies,

modes of overwintering, spectra of host-trees, and

competitiveness. We need to conduct further studies

to help us understand how these species share their

resources, to assess more accurately the risk that they

represent, and to design appropriate control measures.

References Cited

Huart, O. and Rondeux, J. 2001. Genèse, évolution et

multiples facettes d’une maladie inhabituelle affectant

le hêtre en région wallonne. Forêt wallonne 52 :9-19.

DNF. 2002. Maladie du hêtre wallon : évolution et

mesures. Paysages 22 :4-9.

Figure 4.—Distance from the beech stand edge

(open field).

0

100

200

300

400

500

600

700

50 m 100 m 200 m 400 m

Distance from the beech stand edge (open field)

Mean catches

2

Figure 3.—Dispersal of Trypodendron spp. in

recogne, Wallonia, Belguim (02/02/02 to 23/05/02).

0

500

1000

1500

2000

2500

3000

50 m 100 m 200 m

Distance from the beech stand edge (open field)

Mean catches 

0

250

500

750

1000

1250

1500

1750

2000

2250

2500

2750

05/02/0204/03/0211/03/0218/03/0228/03/0204/04/0211/04/0226/04/0207/05/0215/05/0224/05/0207/06/0220/06/0227/06/0208/07/02

Date

Mean catches

Anlier

Croix-scaille

Gedinne

Libin

Figure 2.—Phrenology of T. domesticum.
136 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

Insects are subjected to stress in fresh clearcuts due to changes in microclimate, vegetation, and

trophic links. The objective of this study was to investigate succession in litter insect communities

(most abundant by number of species and individuals of all clearcut insects).

Representatives of the order Coleoptera order were dominant and represented 78% of all trappped

arthropods; 9% were Aranei and 4% were Hymenoptera. The most abundant beetles were in the

families Carabidae (65%), Curculionidae (16%) and Staphylinidae (7%). Entomophagous arthropods

(carabids, spiders, ants) consisted of 69% of all insects found in the litter; 17% of insects recovered

were phytophagous insects, Hylobius weevils, which represented 78% of this number.

Insects in fresh clearcuts aggregate in the periphery or near piles of forest residues. Diversity is lower

within the forest because vegetation in the understory of spruce forests is rather scarce. Special

attention should be directed to the margins of clearcut where most Hylobius weevils were found.

Keywords: clearcut, litter arthropod, pitfall traps, trophic specialization.

Introduction

There have been few investigations of the composition of insects in the litter of forest clearcuts; most

research studies have been limited to insects pests of planted trees (Hylobius, Melolontha, Evetria, Aradus).

The objective of this research was to investigate the

complex of insect communities and their changes in

clearcuts under different management practices. Only

the results from investigations conducted in spruce

clearcuts are presented in this report.

Material and Methods

Research was carried out in 2001 at the Vaišvydava

forest of Dubrava experimental-training enterprise.

Forest litter insects were trapped using pitfall (Barber)

traps – plastic 7 cm diameter 150 ml cup, burrowed in

the soil with its top at the level of the litter. Each cup

was filled with 50 ml of 10% formalin which was changed each month to prevent trapped specimens

from decaying and to prevent removal by birds. Pitfall traps were installed on April 24 and inspected

(emptied, cleaned, replaced, if needed) every 2-3 weeks (Fig. 1).

Seasonal Dynamics in the Abundance of Clearcut Insects

There were two declines in insect abundance during the summer seasons that were recorded in all

trapping zones. Possibly, decrease in insect numbers in June was conditioned by the life history

properties of carabid beetles (egg and larval stages are seldom recovered in pitfall traps). The dynamic

curve of the abundance of insects was similar in both open areas and inside the forest. The least

number of arthropods was trapped in ‘b’ and ‘c’ zones, which were exposed to direct sunlight.

Highest catches were recovered in forest zones ‘d’ and ‘e.’ This suggests that arthropods concentrate at

the periphery of clearcuts and near piles of residues.

Forest Litter Insect Community Succession in Clearcuts of Norway Spruce

Dr. Arturas Gedminas

Lithuanian Forest Research Institute

hauls

1 trap (distanc traps bitween 10m)

24 m

30 m

11 m

10 m

20 m

6 m

5 m

8 m

53 m

1 m

2,5 m

4,8 m

4,1 m

20 m

4 traps (distanc traps bitween 2m)













Figure 1.—Scheme of the distribution of the

pitfall traps on the clearcut.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 137

This evidence is true for the dominant species of

Carabidae and Aranei, while weevils, most of which

are pests of planted trees, were concentrated in the ‘c’

zone (clearcut 10 m from the forest edge). This

suggests that species of Hylobius prefer light and

accumulate closer to breeding sites (stumps) and

feeding sites (seedlings).

Ants can also be considered heliophilous species, since

most of them were trapped in ‘b’, ‘c’ and ‘d’ zones.

Forest litter habitats were preferred also by rove

(Staphylinidae) and scarab beetles (Scarabeidae).

Species richness was lower inside forests zones‘d’ and

‘e’ (Fig. 2). This is expected because there is little plant

diversity within a closed canopy spruce stand. The decrease in the number of species collected in the

middle of July corresponds to a general decline in insect abundance that occurs during this period.

High species numbers recorded in spring catches can be explained in part by the migration of species

to new ecological niches created in the modified environment.

Trophic Associations of Litter Insects

Entomophagous insects were most abundant in the litter as determined by the abundance (69%) of

predacious ground beetles, spiders and ants in trap catches. Entomophagous arthropods prey upon

phytophagous species and are numerous in traps placed within forests; phytophagous insects are also

scarce due to the lack of host plants. The seasonal dynamics curve of phytophagous species

corresponds to the general pattern for all species.

Phytophagous arthropods are more numerous in the clearcuts where forest succession is in the initial

stage with establishing microclimate, vegetation and trophic relations. The number of phytophagous

insects in the clearcut area was dominated by Hylobius weevils. These pests migrate to fresh clearcuts

from nearby stands, attracted by the odor of freshly cut stumps. In addition they find spare food –

planted trees. Concentrations of weevils were noticed in the zone near the forest edge. Therefore

special emphasis on pest management activities should be directed to the peripheral 10 m strip

adjacent to clearcuts.

Conclusions

1. Species of Coleoptera order were dominant and represented 78% of all trappped arthropods;

nine percent of trapped arthropods were Aranei, 4% Hymenoptea, and the remaining 9%

consisted of 10 different insect orders.

2. Representatives of the families Carabidae (65%), Curculionidae (16%), and Staphylinidae (7%)

were the most abundant.

3. Decrease of arthropod abundance in June was influenced by the life history of carabid beetles

(most are in the egg and larval states at that time).

4. Arthropods concentrate in the periphery of fresh clearcuts near piles of slash and logs.

5. Forest litter arthropod species diversity was lower inside spruce stands due to reduced

abundance and diversity of vegetation.

6. Entomophagous arthropods make up 69% of the species recovered in the litter complex, and

consisted mainly of predaceous ground beetles, spiders and ants. Phytophagous arthropods

account for 17% and are dominated by Hylobius weevils (78%).

7. Pest management activities in clearcuts should be directed at the peripheral 10 m strip adjacent

to the residual forest.















     	
 
  
























	












	













Figure. 2.—Litter arthropod species richness

dynamics by zones
138 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

In 2000 and 2001, Trypodendron domesticum L. and T. signatum (F.) (Col.: Scolytidae) were one of

the main causes of the depreciation of more than 1,600,000 m3 of standing beech trees, Fagus

sylvatica L., in Wallonia (Southern Belgium). In 2001, a survey aiming at assessing the range of those

indigenous ambrosia beetles, so far discreet and poorly studied, pointed out that they are

omnipresent all over Wallonia. Two other scolytids and one lymexylonid (Col., Lymexylonidae) were

also frequently caught, which made it possible to outline their regional distribution too.

Key Words: Scolytidae, Trypodendron spp., Xyleborus dispar, Taphrorychus bicolor, Lymexylonidae,

range, Southern Belgium

Introduction

As a consequence of an exceptional frost that severely affected beech trees over a broad area of

Southern Belgium in November 1998, populations of T. domesticum and T. signatum reached

epidemic levels in 2000 and 2001 (Huart and Rondeux 2001). More than 1.6 million m3 of beech

trees were damaged within the two years, almost exclusively at elevations above 350 m a.s.l. (Rondeux

et al. 2002). Apart from the fact that these outbreaks were an economic disaster, the 2001 attacks

were very worrying since they occurred on standing and apparently healthy trees, which is quite

uncommon for both Trypodendron species. Information on these species was very incomplete,

especially from a biogeographical point of view : a survey was thus initiated to outline their range.

Xyleborus dispar (F.) and Taphrorychus bicolor Herbst (Col.: Scolytidae), as well as Hylecoetus

dermestoides L. (Col.: Lymexylonidae) were also frequently caught, which made it possible to outline

their regional distribution.

Materials and Methods

In order to get an idea of the beetles’ distribution, a network of 172 traps was set up throughout the

six natural regions of Wallonia (Fig. 1), from April to October 2001. The traps were hooked on beech

trees (of variable dbh) and baited with ethanol (release rate ca. 250 mg/day). All traps were located in

beech stands (beech relative basal area > 66 %) that were >1 ha., attempting to obtain a homogenous

sample of the Walloon beech forest. Because of the small size of the traps (10 X 23 cm), of the low

number or traps/site, and of the relatively low attractivity of the traps (as compared to attractive

woody material) in physiologically weakened stands, the absence of a species in captures at individual

sites does not necessarily indicate that the species is not present there. For the same reasons, the

number of insects captured was not compared between sites: only the presence was recorded.

Results and Discussion

The number of traps (NT) placed in each Walloon natural region, the number of sites where each

species was caught (number of presences, NP) and the observed presence rate (OPR=NP/NT) is

provided in Table l. Table 1 also provides some characteristics of the Walloon natural regions, such as

the percentage of beech forest (42,400 ha in total) present within each region (BC, according to

Lecomte, in press) and the elevation (E).

Table 1 shows that the scolytid beetles are omnipresent in Wallonia, in all natural regions and at all

elevations. Only H. dermestoides was not captured in the sandy loam and loess regions, but its ecology

and the sampling methodology led to an undervaluation of its range.

Qualitative Survey of Five Beech Damaging Coleoptera

(Scolytidae and Lymexylonidae) in Wallonia (Southern Belgium)

Jean-Marc Henin, Olivier Huart, Philippe Lejeune and Jacques Rondeux

Unit of Forest Management and Economics, Gembloux Agricultural University, Belgium
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 139

The wide distribution of both secondary Trypodendron spp. confirmed that the triggering factor of

the attacks was limited to natural regions where beech trees had undergone damage (Ardenne and

Belgian Lorraine). With other elements, this fact supports the climatic accident hypothesis (early,

sudden and deep frost) since the Ardenne and Belgian Lorraine are the more elevated natural regions

of Wallonia (where the elevation may exceed 350 m), and are characterized by greater and more

sudden fluctuations in temperature.

The attacks were thus probably triggered by an exceptional accident occurring in 1998 (unusual

frost). In 2001, while their populations were at very high levels, T. domesticum and T. signatum

Figure 1.—Distribution of the traps in Wallonia (Southern Belgium)

Table 1.—Number of presence(s) and observed presence rate of each species in different Walloon natural regions

(sandy loam and loess regions are clustered).

BC Elevation NT T. domesticum T. signatum X. dispar T. bicolor H. dermestoides

(m) NP OPR NP OPR NP OPR NP OPR NP OPR

Sandy loam 6 20<E<200 4 3 75 2 50 4 100 4 100 0 0

and Loess

regions

Mosan 8 200<E<350 15 11 73 7 47 11 73 13 87 5 33

Uplands

Fagne- 2 100<E<250 9 6 67 5 56 8 89 6 67 2 22

Famenne

Ardenne 69 200<E<700 128 111 87 69 54 85 66 36 28 20 16

Belgian 15 200<E<450 16 13 81 7 44 11 69 6 38 1 6

Lorraine

Wallonia 100 20<E<700 172 144 84 90 52 119 69 65 38 28 16

BC: Beech cover (in % of the total beech forest area in Wallonia) NT: number of traps

NP: number of presence(s) OPR: observed presence rate (%).
140 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

attacked standing and apparently healthy trees over large areas, which is quite uncommon for these

species. Some additional factors, such as previous storms, repeated droughts, air pollution,

deterioration of soil properties and stand over-ageing probably worsened the situation. So far

however, the reasons of the high and apparently temporary attractivity of many beech trees in 2001

(that did not exhibit frost injuries) are not fully understood. Nevertheless, these events indicate some

fragility of the Walloon beech forests and suggest that silvicultural practices improving the vigor of

the trees (early and regular thinnings, diversification of stand composition and structure) should be

encouraged. At the same time, stress-inducing practices, such as logging methods that damage the

forest floor, or late heavy thinnings creating sudden exposure to light of shade tolerant species (like

beech), should be avoided. In our deciduous forests, it would be also interesting to leave some dead

wood and overmature trees, in order to increase the population level of generalist entomophagous

predators. Some of these, like woodpeckers, have been shown to exert a significant impact on scolytid

population levels (Moore 1972), when the latter are endemic. Such an integrated approach should

enable Walloon forest ecosystems to resist more efficiently such “natural accidents”.

References Cited

Huart, O., and J. Rondeux. 2001. Genèse, évolution et multiples facettes d’une maladie

inhabituelle affectant le hêtre en région wallonne. Forêt Wallonne 52: 8-19.

Lecomte, H. in press. La forêt wallonne, état de la ressource à la fin du 20ème siècle. Ministère de la

Région Wallonne, Direction générale des Ressources naturelles et de l’Environnement, Division de

la Nature et des Forêts, Jambes.

Moore, G.E. 1972. Southern Pine Beetle (Col., Scolytidae) Mortality in North Carolina Caused by

Parasites and Predators. Environmental Entomology 1 (1) : 58-65

Rondeux, J., N. Bourland, O. Huart, and H. Lecomte. 2002. Importance et dispersion de la

maladie du hêtre en région wallonne : premiers résultats d’un inventaire spécifique. Sylva Belgica

109: 22-30.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 141

Introduction

LastCallTM (LC), an attract and kill bait matrix, was deployed for the

management of shoot boring moths in pine plantations and seed orchards.

The targeted moths were the Western pine shoot borer, Eucosma sonomana

(WPSB), European pine shoot moth, Rhyacionia buoliana (EPSM),

Ponderosa pine tip moth, Rhyacionia zozana (PPTM), and Nantucket pine

tip moth, Rhyacionia frustrana (NPTM) in pine plantations and seed

orchards. Attract and kill technology very selectively removes male moths of

the target species from the ecosystem with negligible impact on non-target

organisms. Baits combine the selectivity of pheromone (only 0.21 g/ha,

compared to 3.5-20 g/ha for mating disruption) with the rapid toxicity of

insecticides (only 7.92 g/ha, compared to 500-800 g/ha for conventional

sprays). This bait retains the insecticide within a hydrophobic matrix that

precludes run-off or drift, and thus prevents ecosystem contamination and

damage.

Results

1. Trap catch shut down was observed on all LC treated plots (Fig. 1).

2. On small experimental plots, WPSB will re-infest pine leaders if not treated for one year (Fig. 2).

3. WPSB damage in California was reduced from 55-78% to 2.5-15% (Fig. 3). EPSM damage was

reduced by 30-50% in Poland. This test was limited by the small size of the plot. Studies will be

conducted in British Columbia in 2003.

Management of Shoot Boring Moths from Genera Rhyacionia and

Eucosma with Attract and Kill Technology

R. Hoffman1, D. Czokajlo1, G. Daterman2, J. McLaughlin1, J. Webster3, R. Rynearson4,

M. Gray5

, A. Eglitis6, C. Jensen6, B. Hughes7, P. Flanagan7, L. Spiegel 8, W. Berisford 9, C. Asaro9,

S. Cameron10, J. Seckinger10, L. Sukovata11, A. Kolk11, W. Strong12 and P. Kirsch1

.

1

IPM Tech, Inc., 4134 N. Vancouver Ave. #105, Portland, OR, USA 97217, tel. (503) 288-2493,

 fax. (503) 288-1887, e-mail: ipmtech@ipmtech.com, Web: www.ipmtech.com

2

USDA Forest Service, Corvallis, OR, 3Roseburg Resources, Weed, CA,

4

W.M. Beatty & Associates, McArthur, CA, 5Sierra Pacific Industries, Redding, CA,

6

USDA Forest Service, Bend, OR, 7USDA Forest Service, Wenatchee, WA, 8

US Forest Service, La Grande, OR, 9University of Georgia, Athens, GA, 10International Paper Corp., Savannah, GA, 11Forest Research Institute, Warsaw, POLAND, 12BC Ministry of Forests, Vernon, BC, CANADA

This material is based upon work supported by the Cooperative State Research, Education, and

Extension Service, U.S. Department of Agriculture under agreement No. 2001-33610-11232.

experimental plots in ponderosa pine, Spring 2002

0

10

20

30

40

50

Untreated Treated

Mean # of males (+/-SE)

USFS Bend, OR

SPI, CA

Beatty, CA

Roseburg, CA

Figure 1.—Trap captures of Eucosma sonomana

on LastCallTM experimental plots in ponderosa

pine, Spring 2002.
142 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

5. Damage by NPTM on LC treated plots in North Carolina was reduced by 58% when compared

to untreated plots (Fig. 6).

Discussion

LastCall technology is an effective and environmentally safe method for managing shoot boring

moths in the genera Rhyacionia and Eucosma. With LC treatment, the 60-year harvest rotation of

ponderosa pine can be reduced by at least 5 years and timber yield can be increased by at least 3,940

board feet per acre (Fig. 4). Lack of management of Eucosma sonomana can lead to a decrease in

timber value at the end of the rotation that amounts to at least $1,181 per acre (Fig. 5). IPM Tech

expects EPA registration in Spring 2003 for LC EucosmAK, followed by rapid adoption of this

innovative tactic in western ponderosa pine plantations.

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

Sierra Pacific Ind. Roseburg Resources W.M. Beaty & Assoc.

Change in damage 

(actual value)

LC Center of plot

LC buffer zone (200 yd)

Untreated

Pretreatment damage levels:

 34% 38% 19% 78% 40% 10% 55% 58% 60%

20000

22000

24000

26000

28000

30000

32000

34000

36000

38000

50 55 60 65 70 75 Age

Volume (board foot/acre)

Undamaged

50%

70%

90%

% infested trees:

48

9.6

0

48

48

48

0 36

48

0

36

-35%

-30%

-25%

-20%

-15%

-10%

-5%

0%

5%

10%

15%

20%

25%

Plot I Plot II Plot III Plot IV

Experimental plots (I - IV)(each ca. 2.5 acre)

Change in damage 

(actual value)

2000

2001

2002

Pretreatment damage levels:

23% 31% 36% 12%

Figure 2.—Year to year Eucosma sonomana

damage in ponderosa pine under four

different treatment regimes with LastCall

EusosmAK near Bend, OR, 1999-2002.

Numbers indicate amount of pheromone

(mg/acre) used in the treatment.

Figure 3.—Change in ponderosa pine damage

by Eucosma sonomana on LC WPSB treated

250-acre plots in NE California, 2002.

Plantations received 60g of LC containing

48mg of pheromone per acre.

Figure 4.—Growth predictions for model, undamaged,

and Eucosma sonomana-damaged ponderosa pine in

NE California, 2002. The values were calculated for

measured, mean 22% reduction in annual elongation

of terminal. Site index 80, CACTOS model.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 143

0

2

4

6

8

10

12

50% 60% 70% 80% 90% Fraction of infested trees

Delay in growth comparing to healthy 

trees (years)

-2200

-1700

-1200

-700

-200

300

Value loss per acre ($)

Delay in volume

increments (years)

Value loss for entire

rotation

Treated Untreated

Damage reduction (%)(bars)

Pre-treatment

Post-treatment

0

10

20

30

40

22-Mar

24-Mar

26-Mar

28-Mar

30-Mar

1-Apr

3-Apr

5-Apr

7-Apr

9-Apr

11-Apr

13-Apr

15-Apr

17-Apr

19-Apr

21-Apr

23-Apr

25-Apr

27-Apr

29-Apr

Mean # of males (lines)

LC 0.16%

LC 0.016%

Untreated

Figure 5.—Growth delay (years) and value loss

($) of ponderosa pine infested with WPSB at

different levels and average 22% loss of

terminal elongation. Values calculated for 70

year rotation in NE California, CACTOS model,

SI 80, $300/Mbf. Maximum value = 35,790 bf.

Figure 6.—(1-Lines) Trap catch: Rhyacionia

frustrana, (2-Bars) Damage reduction (%)

on LC 0.16% treated plots, Georgia, 2002.
144 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

During the 1900s, the amount of dead and decaying wood has declined drastically in boreal forests in

Finland because of intensive forest management. As a result, species requiring such resources have

also declined or have even gone extinct. Recently it has been observed that in addition to old-growth

forests, natural, early successional phases are also important for the biota of boreal forests. Because of

the effective prevention of forest fires and clearing of forests after storms, the early successional stages

that normally contain an abundance of dead wood, have become almost absent in forest dynamics.

The development of more ecological approaches to manage production forests is needed to protect

threatened species successfully and to enhance their recovery.

The natural-like, early successional phases can be created in several ways in managed forests. Based on

previous descriptive studies, the two most important factors to be considered are the number of trees

left in the regeneration areas, and the use of fire to promote more natural characteristics. The

ecological and quantitative effects of these factors are, however, largely unknown.

Our large-scale field experiment is being conducted in mature pine-dominated forests with some

mixture of spruce and birch. The size of each study plot is 3–4 hectares, corresponding roughly to the

size of a typical regeneration cutting in southern Finland. There are three levels of green tree

retention—0 m3

/ha, 10 m3/ha, 50 m3/ha—and no cuttings as control. Each treatment combination is

replicated three times. Prescribed burning was conducted on 12 of the 24 study plots. All the study

areas are located in eastern Finland. In every study plot, 20 window flight traps and 20 pitfall traps

are installed to catch beetles. The data have been collected before and after the experimental cuttings

and burning; the trapping of beetles will be continued until the end of year 2003.

Since only part of the vast amount of material is identified completely, the results are preliminary.

The data presented here represent only the one-month period immediately after the burnings

conducted in 2001. According to the results, it seems clear that threatened species benefit from forest

burning. It’s likely that the treatments affect the beetle assemblages, but so far the data consist of only

the first colonizers arriving at the areas. The effect of the level of green tree retention to the beetle

assemblages will be examined further when all of the data are available. It also appears that many

beetle species are very rapid to colonize new resources produced by fire, and also by cuttings. These

preliminary results indicate that by using fire also in commercial forests, population levels of at least

some threatened species can be enhanced significantly.

Fire as a Tool in Restoring and Maintaining Beetle Diversity in Boreal Forests:

Preliminary Results from a Large-scale Field Experiment

E. Hyvärinen, H. Lappalainen, P. Martikainen and J. Kouki.

University of Joensuu, Finland
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 145

The web-spinning sawflies (Cephalcia Panz.) are members of the Symphyta that are of economic

significance, and which constitutes an integral part of the spruce forest environment. Spruce, which

is the dominant component of Western Carpathian forest stands, is the only known host plant for all

the species of Cephalcia. Species in this genus occasionally appear in high densities at which time they

become a major threat to coniferous forest stands especially in the mountains. Gradations develop

very slowly but may persist for several years. Defoliation by these insects causes a reduction in radial

increment and weakens trees so that they are susceptible to attack by secondary organisms and by

drought. This may result in extensive tree mortality over large areas. Monolithic spruce forest stands

of artificial origin are attacked, as are stands of natural origin in middle and older age classes that are

located at altitudes of 800-1200m.

C. alpina (Klug) (= fallenii Dalm) was found for the first time in the Gorce Mountains of Poland;

this also represented the first mass appearance of this species in Europe. C. alpina occurred in Gorce

spruce forest stands at altitudes of from ca. 900 to 1200 m. The insect finds optimum conditions for

its development and survival in monolithic spruce forest stands in the upper mountain regions

associated with the plant community characterized by Piceetum excelsae carpaticum. During the only

gradation recorded so far, traces of feeding damage were noticed before the 1979 growing season on

the mountain sides of Kudloń, Mostownica and Jaworzyna Kamienicka. In the summer of 1979, the

feeding damage expanded around these original foci, including artificially established spruce stands

of middle and older age classes. The forest stands located there were damaged significantly (60-90%)

and moderately (30-60%) in an area of ca. 580 ha. Forest stands on 1600 ha located around these

foci were lightly damaged (>30%). Despite extensive swarming in 1980, the population declined and

remained at low levels until 1982. In subsequent years, the population declined even further and,

beginning in 1985, C. alpina was not considered to be a threat to forest stands. One may conclude

from this description of the gradation that populations probably increased for several years prior to

1979. It is probable that its onset was synchronized with a gradation that occurred in the Radziejowa

massif, where light feeding damage first appeared in 1976; at that time, the population of the insect,

initially called C. abietis (L.), and the area of its incidence were definitely smaller than in Gorce. The

gradation period was therefore 10 years (1976-1985). As a result of several years of defoliation of

spruce growing at high altitudes, resistance thresholds of natural spruce stands were exceeded.

Weakened trees were killed by Armillaria spp. and species of bark beetles in areas above 850 m.

Spruce trees were drying out in large numbers so that during the period from 1984 to 1990, a

forested area of 140 ha was salvaged. Over another 266 ha, tree mortality varied from 21-100%.

After the C. alpina gradation in Gorce disappeared, a sudden increase in population was detected in

Beskid Ślaski in an area near the summit at Skrzyczne at an altitude of 1000-1200 m. Populations of

this pest persisted there from 1982 to 1986. Analysis of entomological material collected from the

areas of mass incidence of C. alpina, Beskid Ślaski, in an area near the summit at Skrzyczne at the

altitude of 1000-1200 asl. Populations of this pest persisted there from 1982 to 1986. Analysis of

entomological materials collected from the areas of mass incidence of C. alpina, (Beskid Ślaski from

the 1976-84 gradation period, the Gorczański National Park (1978-85), the Sudety mountains

(1982-84) and Gdańsk (1993-1996) allowed us to conclude that a large percentage of web-spinning

sawflies identified as C. alpina, possessed morphological features of C. annulicornis (Hartig). Both

species appeared together in the gradation areas, but their ratio varied considerably from area to area

without any apparent relationship to environmental aspects, type of forest stands, altitude, and local

climate. This species has been known to occur in the Beskidy region since the 1980s. Observations of

the major swarming in the Skrzyczne massif during those years indicated that possibly several

Location, Evolution and Importance of Cephalcia spp. (Hym: Pamphiliidae)

Populations in Polish Carpathian Mountains

Marcin Jachym

Forest Research Institute, Department of Forest Management in Mountain Regions

 Ul. Fredry 39, 30-605 Cracow, Poland
146 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

variations of C. alpina might exist. Research to identify the characteristics of the two web-spinning

sawflies was conducted in Italy from 1990-1995. Entomological materials used for research on the

biology of these species were obtained from the Czech Republic, Poland and Italy. The role of each

species in high-density populations was determined based on analyses of insects in entomological

collections from the Czech Republic, Germany, Poland and Italy, and on examination of published

literature.

Since 1980, C. arvensis (Panz) has been recorded along with these species. Since 1978, in the lower

elevations a new species appeared, C. abietis (L.), which has displaced the other species of this group

over the past twenty years. The gradation has been spreading towards the south along the mountain

ridge and towards the valleys on the western and eastern sides of the mountain ridges at an altitude of

600-800 m.

A detailed analysis of the data available on Cephalcia spp. incidence in the last 20 years indicate that

there is a lack of permanent outbreak foci of these insects at a micro-geographical scale. The

incidence of web-spinning sawflies resembles a mosaic overlaid on a background of spruce forest

stands. Individual 2- and 4-year cycles are apparent for particular species on small areas, as is the

expansion of populations and their appearance in new locations. The replacement of existing

populations by other species has also been noticed: initially, C. arvensis was the dominant species,

then C. alpina, and ultimately C. abietis.

Currently, the incidence of web-spinning sawflies in the Carpathian Mountains is common but at

low populations. However, an increase in the population of C. alpina has been noticed, associated

with C. erythrogaster (HTG). Monolithic spruce forest stands located at an altitude of 600-1200 m in

the western part of the Carpathian mountains in Beskid Ślaski and Żywiecki, at their summit and

along mountain ridges, will continue to be the most affected.

Gradations of Cephalcia spp. have persisted in spruce forest ecosystems in mountainous regions

because of disturbances caused by forest management activities and exacerbated by atmospheric soil

and water pollution, which in turn are related to poor economic conditions.

References Cited

Battisti A., Boato A., Zanocco D. 1998. Two sibling species of the spruce web-spinning sawfly

Cephalcia fallenii (Hymenoptera: Pamphiliidae) in Europe. Systematic Entomology 23:99-108.

Blank S.M., Shinohara A., Taeger A. 1998. Revisionary Notes on Pamphilid Sawflies. Mitt. Mus.

Nat.kd. Berl., Dtsch. Entomol. Z. 45:17-31.

Capecki Z. 1982. Masowe wystapienie zasnui wysokogorskiej – Cephalcia fallenii (DALM)

(Pamphiliidae, Hymenoptera) w Gorcach, Sylwan 126 (4): 41-50.

Honowski, J. Huflejt, T. 1998. O wystepowaniu zasnui wysokogorskiej, Cephalcia fallenii

(DALM.)(Hymenoptera, Pamphiliidae) w Gorczanskim Parku Narodowym. Polskie Pismo

Entomologicane 58: 433-446.

Jachym, M. 1999. Forecast and control of the spruce web-spinning sawflies (Cephalcia sp.) in the

Beskidy mountains in Poland in 1998. Methodology of Forest Insect and Disease Survey in

Central Europe. Proceedings of the IUFRO WP 7.03.10. Sion: 164-167.

Jasica, T. 1985. Zasnuja wysokogorska w.Beskidzie Sadeckim. Las Polski, 5:9-10.

Kosibowicz, M., Jachym, M. 1998. The spruce web-spinning sawflies (Cephalcia sp.) in the Beskidy

mountains in Poland – occurrence, importance and control. Methodology of Forest Insect and

Disease Survey in Central Europe. Proceedings of the IUFFO WP 7.03.10. Jaszowiec. Poland: 85-87.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 147

Phytophthora decline of alder was first observed in Hungary in 1999 in Hanság (NW Hungary, close

to the Austrian border –designated by “H” on the map.

The Department of Forest Protection, Hungarian Forest Research Institute (FRI) started a long term

monitoring project in 2001 on Phytophthora decline of alder, specifically to determine the importance

of the disease, the extent of damage, and severity of the infection in different regions of the country.

During preliminary investigations in 2001, 57 fen type alder forests and riparian type alder forests

were investigated over a distance of 100 km. Results of this investigation were reported by Koltay

(2002) in Prague. Experimental plots are being established in 2002 in order to determine presence/

absence of the disease, and to measure the rate and intensity of the infection. Ten new plots have been

established to date and another 10 plots will be established in the future (see map). Stands that

contained more than 3% of infected trees in different age classes and of different origins were selected

as experimental plots. All plots contain 50 sample trees with the exception of two plots which contain

100 trees. Up to now we have examined each site once per year, but beginning in 2003 we will visit

the plots twice each year (late spring and autumn).

Methods Used for Investigating the Incidence of Phytophthora

Disease of Alder in Hungary

A. Koltay1, J. Bakonyi2 and Z. Á. Nagy3

1

Hungarian Forest Research Institute, 1023 Budapest, Frankel L. u. 42-44.

 E-mail: h13852kol@ella.hu

2

Plant Protection Institute, Hungarian Academy of Science, PO Box 102, Budapest

 E-mail: Jbak@nki.hu

3

Plant Protection Institute, Hungarian Academy of Science, PO Box 102, Budapest

 E-mail: Znagy@nki.hu

Distribution of Alder

in Hungary

Investigation plots

Intended investigation plots
148 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Investigative methods are as follows:

Data sheet for each tree

•Location of plot

•Number of plot

•Date of investigation

•GPS code

•Tree number

•Age

•Origin - Seed, Coppice, or Mixed

•Diameter at 1,3 m

•Height class by Kraft (1-4)

•ALNUS (1-5) - General condition of the tree on the strength of crown condition

1. Previously killed tree, usually without dead twigs

2. Recently killed tree, without leaves but with some dead twigs.

3. Typical decline symptoms in the crown, reduced foliage with leaves smaller than normal, abundance

of dead twigs and branches

4. Initial symptoms of crown decline, sparse crown, and in many cases leaves smaller than normal.

5. Healthy and full crown, with green, normal sized leaves

•Leaf cast (0-10), measure of lost leaves, 0 = no leaf cast, 10 = 100% leaf cast

•Leaf chewing (0-1), 0 = No, 1 = Yes

•Leaf discoloration (0-1), 0 = No, 1 = Yes

•Leaf measurement (0-1), 0 = No, 1 = leaves smaller than usual

•Twig dying (0-1), 0 = No, 1 = Yes

•Branch dying (0-1), 0 = No, 1 = Yes

•Top drying (0-1), 0 = No, 1 = Yes

•Abnormal fruiting (0-1), 0 = No, 1 = Yes

•Tarry spots (0-1-2), 0 = No, 1 = Yes, 2 = Not clear

•Number of tarry spots on root swelling, from the soil to 50 cm high on trunk

•Number of tarry spots on trunk, higher than 50 cm

•Wound on stem, (0-1), 0 = No, 1 = Yes

•Wound callus on stem, (0-1), 0 = No, 1 = Yes

•Insect damage on stem (0-1), 0 = No, 1 = Yes

•Water sprout (0-1), 0 = No, 1 = Yes

In addition to monitoring the incidence of Phytophthora decline of alder in Hungary, we have begun

identifying Phytophthora from our experimental plots in different regions of Hungary. These

investigations are conducted in laboratories of the Plant Protection Institute, Hungarian Academy of

Sciences.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 149

Isolation methods are described below:

Soil samples containing infected roots were collected around obviously declining trees that exhibited

typical tarry exudation on the lower stem. Two or three subsamples were taken from different

cardinal directions at 0.5-1.5 m from the stem and were mixed. Isolates were baited by leaves of

common Cherry-laurel (Prunus laurocerasus) according to Themann and Werres (1998).

Symptomatic leaves were then washed under running tap water, disinfected in 10% sodium

hypochlorite, rinsed in sterile tap water and dried on paper towels. Pieces of leaves were then placed

on selective pea-broth agar (Tuite 1969) amended with 250 mg ampicillin, 10 mg pimaricin, 10 mg

rifampicin 50 mg benomyl, 50 to 100 mg PCNB and 50 mg hymexazol per litre.

In addition to baiting, isolations were also made by direct plating of washed and surface disinfected

root pieces onto selective media. Plates were incubated at 25 °C in the dark. Developing colonies

were purified from contaminants by repeated transfer of the cultures onto the selective medium or

3% water agar (Abdelzaher et al. 1994). Pure cultures were subjected to morphological examinations.

These investigations are supported by the Hungarian Science Foundation (OTKA F 038325, OTKA

T 038309)

References Cited

Abdelzaher, H. M. A., Ichitani, T. and Elnaghy, M. A. 1994. A technique for isolating bacteriafree Pythium spp. from pond water. Mycoscience 35 433–434.

Koltay, A. Phytophthora disease of alder in Hungary. Methodology of Forest Insect and Disease

Survey in Central Europe, Proceedings of the Second Workshop of the IUFRO WP. September

17-21, 2001, Prag

Themann, K. and Werres, S. 1998. Verwendung von Rhododendronblattern zum Nachweis von

Phytophthora-Arten in Wurzel- und Bodenproben. Nachrichtenbl. Deut. Pflanzenschutzd., 50, 2:

37–45.

Tuite, J., ed. 1969. Plant Pathological Methods. Burgess, Minneapolis, USA

Varga, F. 2000. A mézgás éger fitoftórás betegségének megjelenése Magyarországon. 46. Növ. Véd.

Tud. Napok. Összefoglaló p. 126
150 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

The genetic structure of Ips typographus populations in the Tatra Mountains was studied based on the

observed differences of gene flow and migration rate. It was a highlighted question as to what extent

different natural barriers influence the migration potential of the species.

Material and Methods

Samples of Ips typographus adults were collected from attacked trees (first generation) in the following

valleys of Tatra: Southern part, Ticha dolina (TI), Koprova dolina (KO), Mengusovska dolina (ME),

Velka Studena dolina (VS), Northern part: Javorova dolina (JA), and Bielovoda dolina (BI). Within

the Bielovoda dolina samples were taken at different altitudes: 900m (BI9), 1100m (BI11), 1300m

(BI13 and BI13B), and 1400m (BI14) respectively. Only parental beetles were taken to avoid the

effects of the homogeneity of the “one-family” beetles. Isoenzyme analyses were carried out using the

NATIVE PAGE method.

Statistical analyses of the results were made applying different genetic structure describing statistics

(FStat, Biosys, Popgene, and Slatkin’s). Allele frequency and genetic distance values were calculated.

Dendrograms were constructed to demonstrate the relationships among the locations. Gene flow and

migration rate was estimated using graphical (Slatkin’s method) and statistical (F statistics) methods.

All analyses were made over all populations and loci.

Results and Discussion

The proteins of 12 enzymes (22 loci) were stained and five of them were polymorph. The five

polymorph loci (Aat-2, Amy-1, Est-2, Est-3, Est-4) had 8 10, 15, 9, and 4 alleles (Table 1.).

All investigated loci were in the Hardy-Weinberg equilibrium at the significance level of p=0.001.

The effective number of alleles varied strongly from 1.054 (Est-4) to 5.152 (Est-2), with an average of

2.319. The observed heterozygosity (HObs.) was high, with heterozygote deficiencies on two loci (Est2, Est-3).

Migration Features of Ips typographus in the Tatra Mountains:

Using a Genetic Method

Ferenc Lakatos

University of West-Hungary, Institute of Forest and Wood Protection, H-9400 Sopron,

 Bajcsy-Zs. u. 4.

Table 1.—Observed number of alleles

Locus Population All

Populations BI9 BI1 BI13 BI13B BI14 TI JA ME KO VS

Aat-2 7 5 5 5 5 3 34 4 4 8

Amy-1 5 6 7 8 7 7 6 9 9 6 10

Est-2 14 13 12 12 11 12 11 13 12 12 15

Est-3 9 8 8 5 7 4 67 6 7 9

Est-4 4 1 3 2 2 3 12 2 1 4

Mean 7.8 6.6 7.0 6.4 6.4 5.8 5.4 7.0 6.6 6.0 9.2

St. Error 1.8912 2.1966 1.6956 1.8908 1.6432 1.9171 1.8908 2.1506 1.9875 2.0310 1.9812
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 151

Nei’s genetic distance values (D = 0.0067 to 0.0167) in the investigated area were rather close to the

values found in an area of similar size in Hungary (D = 0.0018 to 0.0289). All populations showed

high genetic variation. Most of the genetic differences were found within the individual populations;

only 1.6% of the differences could be attributed to differences between populations (FST=0.016).

Using Nei’s genetic distance values for constructing a dendrogram for the locus Aat-2 with the

“neighbor joining” procedure (Fig. 1.), the investigated populations were grouped into three main

groups: (a): the populations from Bielovoda dolina lower elevations (BI9 and BI11), (b): the

populations from Bielovoda dolina higher elevations (BI13, BI13B and BI14) with the neighbouring

Javorova dolina (JA) and (c): the populations from the southern valleys (ME, KO, VS). Only the

population from Ticha dolina (TI) did not group with its geographical origin (group c), but with

northern populations (group b).

The migration rates (Nm) are high among all investigated Ips typographus populations. These results

support previous observations that imagines fly greater distances and cover significant distances in

areas where there are no host plants, and that they can disperse over higher mountain peaks.

Comparative studies showed migrational potentials in the Tatra (Nm = 19.70 to 51.16) were similar

those in Hungary (Nm = 10.96 to 63.37; Lakatos, 1998) and in Southern Germany (Nm = 22.96 to

64.35; Gruppe, 1997).

References Cited

Gruppe, A. 1997. Isoenzymatische Variation beim Buchdrucker Ips typographus. Mitt. Dtsch. Ges.

Allg. Angew. Ent. 11: 659-662.

Lakatos, F. 1998. Genetic variation of Ips typographus L. populations from in and outside of the

native range of its host Picea abies (L.) Karsten. In: J. Hayes and K. Raffa ed.: Proceedings of a

Workshop on Bark Beetle Genetics: Current Status of Research. Madison, Wisconsin, USA: 12-14.

 +-----------------------------------------------------BI9

 ! 

 ! +-----------------BI11

--9 ! 

 ! ! +BI13

 ! ! +--4 

 ! ! ! +BI14

 +----------------------------------8 +--5 

 ! ! ! +BI13B

 ! +--6 +--3 

 ! ! ! +TI 

 ! ! ! 

 +-------------7 +--JA

 ! 

 ! +ME 

 ! +--1 

 +----2 +VS 

 ! 

 +KO 

Figure 1.—Dendrogram based on Nei’s genetic distance values (1972), neighbour joining method

(populations in italics are from lower /1100m and below/ elevation, populations in bold are from the

southern part, all the others from the northern part of the Tatra Mountains)
152 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Introduction

Several species of bark beetles occur frequently in the upland spruce forests of the Czech Republic;

some of them are serious pests that may cause vast destruction of forest stands. In the last decade, a

complex of several species from the genera Ips, Pityogenes and Polygraphus contributed to large-scale

devastation of thousand hectares of spruce forest in the Šumava Mountains and in Northern

Moravia. To understand the course of such outbreaks and to appreciate the role of natural enemies in

bark beetle population dynamics, we investigated the importance of braconid parasitoids that attack

several species of bark beetles.

Braconids represent the second most numerous family of parasitic Hymenoptera and include more

than 20,000 species worldwide. Thirty-eight percent of braconid genera are associated with different

stages of Coleoptera, most often from families (Scolytidae, Bostrychidae, and Cerambycidae) that are

rarely attacked by other hymenopetrans (Belokobylsky 1996).

The present work extends these observations by demonstrating the occurrence of two additional

braconid species and providing counts of bark beetles and braconids that emerged from sample logs

collected in several upland (550-1200 m) spruce stands in the Czech Republic.

Methods and Materials

The communities of spruce bark beetles and their insect enemies, especially braconid wasps, were

examined in sample logs that were cut twice per year during 2000-2002 from spruce trees felled in

the listed forest localities. Logs were placed in photoeclectors, which are light-tightly closed tin

cylinder about 1 m long and 25 cm in diameter, with a small hole near the top and another one close

to the bottom where the emerging insects escape into collecting vials. Emerged insects were collected

every 4 days, during the season, and at longer intervals in early spring and late autumn. Almost

10,000 specimens of bark beetles and 700 specimens of braconids were obtained.

Areas Investigated

The samples (tree logs) were collected from eight localities within four upland forest areas throughout

the Czech Republic: Šumava Mountains/National Park (Březník (near Modrava, 1000-1200m;

Černá hora, 1100-1200m; Strážný, 1000m; České Žleby, 800m; Stožec, 900m), Krkonoše

Mountains (Špindlerův Mlýn, 750m), Bílé Karpaty Mountains (Velké Karlovice, 550m) and

Českomoravská vrchovina hills (Čiměř, 550m).

Braconids Associated With Bark Beetles

Eight braconid species - Coeloides bostrichorum Giraud, Cosmophorus regius Niez., Dendrosoter

middendorffi Ratz., Cosmophorus klugii Ratz., Rhopalophorus clavicornis Wesm., Ecphylus sylesiacus

Ratz., Spathius rubidus Rossi, and Meteorus varinervis Tobias - were found in the logs attacked by the

bark beetles of the genera Ips, Pityiogenes and Polygraphus.

Rate of Control

The rates of bark beetle control by the braconids were assessed from the ratio between the numbers of

emerged bark beetles and parasitoids. Assessments were done separately for each locality and year.

Braconid (Hymenoptera, Braconidae) Parasitoids of Bark Beetles

in Upland Spruce Stands of the Czech Republic

Aurel Lozan and Jiří Zelený

The Institute of Entomology, Czech Academy of Sciences, Branišovská 31, 370 05

 České Budějovice, Czech Republic. E-mail: lozan@entu.cas.cz
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 153

The rate of parasitism varied in space and time between 1.6% and 40.5% and was often high in

comparison with the abundance of other natural enemies, suggesting that braconids may play a

significant role in the regulation of bark beetles. In exceptional cases registered in the Šumava

Mountains, Coeloides bostrichorum destroyed 40% of the host complex Ips typographus + Ips amitinus,

and Ropalophorus clavicornis 30% of Polygraphus poligraphus. Cosmophorus klugii eliminated 1.6%

Polygraphus poligraphus + Ips typographus in Černá hora and as much as 19% of Polygraphus

poligraphus in Březník. Dendrosoter middendorffi was present in five photoeclectors showing a low

parasitism rate, from 0.3% of Ips typographus + Pityogenes chalcographus (Velké Karlovice) to 4.6% of

Ips typograpus (Čiměř). Ecphylus silesiacus killed from 0.5% hosts in the complex Ips amitinus + Ips

typographus + Pityogenes chalcographus in České Žleby to 5.2% of Ips typographus + Ips amitinus in

Březník. The three remaining braconid species had negligible impact on the host populations.

Conclusion

Our results demonstrate that considerable numbers of spruce bark beetles can be killed by braconids

in the upland forests of the Czech Republic. From the eight braconid species we collected, Coeloides

bostrichorum destroyed as much as 40% of the complex Ips amitinus + I. typographus, and

Ropalophorus clavicornis 30% of Ips typographus. We conclude that braconid wasps may regulate the

population dynamics of bark beetles.

Forest management should take advantage of such natural processes, as is the biological control of

xylophagous species. Minimally managed “microreserves” should be set aside for the maintenance

and regeneration of insect predators and parasitoids.

Acknowledgments

The work was possible due to financial support of the Research Project of the Academy of Sciences of

the Czech Republic (Grant No. S5007015). We want to thank Dr. M. Čapek (Brno) for his help in

identifying some of the collected braconids and Prof. F. Sehnal for the help with the poster

preparation.

References Cited

Belokobylsky, S.A. 1996. Parasitism on the beetles (Coleoptera) as important stage in the evolution

of braconid wasps (Hym., Br.) I. Entom.Obozr. 55: 660-677; II. Entom.Obozr. 55: 790-814. (In

Russian).

Bouček Z., Půlpán, J. and Śedivý, J. 1953. Poznámky o blanokřídlých cizopasnících kůrovce

smrkového, Ips typographus L., v ĆSR. Folia Zool. Ent. 2: 145-158. (In Czech). [Notes on parasitic

hymenopterans of the bark beetle Ips typographus L.].

Čapek, M. 1996. Lumčícovité (Hym.: Braconidae) ako parazitoidy podkornikovitých (Col.:

Scolytidae). Conf. Proceedings Biodiverzita. z aspektu ochrany lesa a polovnin, Zvolen, pp. 27-33.

(In Slovak). [Braconids (Hym.: Braconidae) as parasites of bark beetles].

Doležal, P. and Zelený, J. 2001. Bark beetles (Scolytidae, Col.) and their insect bioregulators in

mountain spruce stands. J.Forest Sci. 47: 73-76.

Hedquist, K.J. 1998. Bark beetle enemies in Sweden. II. Braconidae (Hymenoptera). Entom.

Scandin., Suppl., 88 pp.

Turčáni, M. and Čapek, M. 2000. Výsledky štúdia parazitoidov a hmyzích predatorov podkornych

škodcov borovice lesnej (Pinus sylvestris L.) v reliktných borinách Slovenského raja. Forestry J. 46:

381-392. (in Slovak). [Results of investigations on the parasitoids and predators of the bark pests

of the scotch pine (Pinus sylvestris L.) in relict pine forests of Slovenskí raj].
154 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Effect of Aerial Sprays on the Abundance of Litter Insects

Jurat  ̄ e ̇ Lynikiene ̇ and Paulius Zolubas

Lithuanian Forest Research Institute, Girionys, 4312 Kaunas, Lithuania

Abstract

The research objectives were to determine the species composition and seasonal dynamics of pine

litter arthropods and examine the effect of insecticide treatments on non-target organisms associated

with pine beauty moth (Panolis flammea Schiff.) outbreaks. Representatives of beetles (Coleoptera)

were the dominant arthropods collected (65.6% of 20,500). The average numbers of arthropods

captured per trap were as follows: 37.03 ± 7.16 in Foray 48 B sprayed plots; 30.45±1.66 in Arrivo

sprayed plots; 24.10±3.78 in control (unsprayed) plots.

Keywords: Panolis flammea, aerial sprays, insecticides

Introduction

Damage caused by defoliating insects usually expands over large areas and in many cases may cause

extensive tree dieback in pine forests. Chemical or biological insecticides are often applied to prevent

defoliation. Arthropods are very important in the self-regulation of forest ecosystem processes; spiders

and other arthropods can efficiently control insect pest abundance in the forest litter (8B28=>20

1985). However 40% of beneficial insects were impacted by aerial treatment of forests with

pyrethroids, 15% of them being entomophagous species (Žiogas 1995). Therefore, investigations of

the impact of aerially applied chemical and biological insecticides on non-target organisms during

area-wide pest suppression programs are always of high importance.

In May, 2001, 3150 ha of pine forests were sprayed with Foray-48B and 1547 ha with Arrivo to

control the pine beauty moth (Panolis flammea Shiff.) in 2001. The research was conducted to

evaluate the impact of these forest protection treatments (aerial spray) on the abundance of pine litter

arthropods.

Methods

The research was carried out in pine beauty moth (P. flammea) outbreak populations in

Druskininkai, Varena forest enterprises and Dz ̄  ̇ ukija national park pine forests. Litter arthropods

were captured in pitfall traps (150 ml, 6.5 cm diameter plastic cups) filled with 10% formalin. Traps

were installed two weeks before spraying was conducted and emptied once or twice each month

between May and October. 24 traps were placed in forest plots sprayed with Arrivo (conventional

pyrethroid), 24 traps in plots sprayed with Foray 48B (microbial pesticide), and 24 traps in a forest

plot designated as an untreated control. Traps were placed in 2x2 m rectangle design with three

replications; the distance between replications was 20 m ( 1971). Trap results were

calculated for 20-day periods in order to compensate for irregularities in collecting dates between

treatments.

Results

Approximately 20,500 arthropods were collected and identified in the study plots. Beetles

(Coleoptera) dominated the collections and represented 65.6% of all collected arthropods. Within

the Coleoptera, the three dominant families were as follows: Carabidae (ground beetles) 70.8%;

Curculionidae (weevils) 13.2%; Staphilinidae (rove beetles) 9.6%. Other groups captured included

Aranei (mites) 11.7%, and Hymenoptera (11.7%) (Table 1).
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 155

The number of arthropods in Foray 48B sprayed plots averaged 37.03±7.16 specimens per trap. In

Arrivo sprayed plots the average number was 30.45±1.66, and in the control (unsprayed) it was

24.10±3.78. The increased abundance of pine beauty moth larvae in outbreak areas had a positive

influence on the number of litter insects captured. The abundance of litter arthropods essentially

increased after treatment with Arrivo; in June-July the catch was over two times greater than in May

(Table 2). These differences were statistically significant. A similar increase in trap captures was

observed in Foray 48B treated plots, where catches after treatment increased from 38.15±9.42 to

65.78±6.32. This difference can be explained by the large number of pine beauty moth larvae that

dropped from the forest canopy after treatment; this created a vast food supply which was attractive

to entomophagous arthropods (spiders and ground beetles in particular) from surrounding stands.

Table 1.—Pitfall trap captures in pine beauty moth plots

Order Abundance Family Abundance

Coleoptera 65.6% Carabidae 70.8%

Diptera 1.1% Elateridae 1.3%

Hymenoptera 11.7% Scarabaeidae 3.4%

Lepidoptera 1.1% Curculionidae 13.2%

Aranei 19.9% Staphilinidae 9.6%

Other insects 0.6% Silphidae 0.8%

Other beetles 0.9%

The seasonal dynamics of ground captures/trap in the Foray 48B plot as compared to the unsprayed

control can be explained by the slower action of the biological preparation (Žiogas 1995). The

number of arthropods captured in the pyrethroid sprayed plots increased immediately after treatment

(June), however in the Foray 48B treated plots, this increase came later (July-August) and was not as

large. Three months after treatment (September) there was no significant difference in the average

abundance of litter insects among the treatment and control plots.

Conclusions

1. The representatives of the order Coleoptera (beetles) dominated the pitfall trap captures and

represented 65.6% of all collected arthropods.

2. Number of arthropods per trap in the Foray 48 B sprayed plots was 37.03±7.16 in Arrivo

sprayed plots 30.45±1.66, and 24.10±3.78 in the control plot (unsprayed).

Table 2.—Effect of different treatments on arthropod abundance

Month Abundance in different treatments, number/trap/20 days

Arrivo Foray 48B Control

May 23.25 ± 2.54 a 38.15 ± 9.42 ac 33.19 ± 5.10 ab

June 53.44 ± 2.41 b 28.56 ± 2.67 b 17.42 ± 2.14 bc

July 55.17 ± 2.51 b 65.78 ± 6.32 a 33.80 ± 2.82 a

August 8.15 ± 78 c 42.42 ± 6.72 a 15.51 ± 1.86 c

September 26.09 ± 0.63 a 39.87 ± 6.01 ab 40.92 ± 5.90 a

October 8.81 ± 1.11 c 8.54 ± 0.83 c 12.86 ± 4.86 c

Average 30.45 ± 1.66 37.03 ± 7.16 24.10 ± 3.78

Values followed by same letter do not significantly differ (Student t-test, p=0.90)
156 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

3. After treatment with Arrivo, the abundance of litter arthropods increased significantly for two

months (June-July) and later decreased to the same level as in the control plots.

4. After treatment with Foray 48B, there was a slower increase in the abundance of litter arthropods

however the average number/month was higher.

References
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 157

Bark Beetles (Coleoptera: Scolytidae) in Slovenia

Ecological conditions in Slovenia are very complex and heterogeneous due to the influence and

interaction among the various climatic, tectonic, edaphic, orographic, lithologic - transitional

(ecotonic) regions. Slovenia is a meeting-point of the Alps, the Mediterranean, the Dinaric Mountain

Region and the Pannonian Lowland. This complexity of ecological factors has created a wide variety

of habitats and accounts for the high degree of biodiversity of flora and fauna. As a result of the work

of Slovenian entomologists, we now have a preliminary catalogue of species from the family

Scolytidae. At last count (Grüne 1979) there were 154 species in the Scolytidae family in Europe.

From publications and Slovenian collections (Central Collection of Slovenian Museum of Natural

History, Coleoptera-Rhynchophora, S. Brelih; Gspan collection; Collection of the Department of

Forestry and Renewable Forest Resources, Biotechnical Faculty, M. Jurc) we have established that

there are 88 species from the family Scolytidae in Slovenia:

Scolytus scolytus (Fabricius), S. laevis Chapuis, S. multistriatus (Marsham), S. pygmaeus

(Fabricius), S. ratzeburgi Janson, S. intricatus (Ratzeburg), S. mali (Bechstein), S. rugulosus

(Müller), S. carpini (Ratzeburg), Phloeotribus scarabaeoides (Bernard), Phthorophloeus

spinulosus Rey, Phloeophthorus latus (Wichmann), P. geschwindti (Seitner), Hylastes ater

(Paykull), H. opacus Erichson, H. linearis Erichson, H. attenuatus Erichson, H. angustatus

(Herbst), H. cunicularius Erichson, Hylurgops glabratus (Zetterstedt), H. palliatus

(Gyllenhal), Tomicus minor (Hartig), T. piniperda (Linnaeus), Hylurgus ligniperda

(Fabricius), Dendroctonus micans (Kugelann), Polygraphus poligraphus (Linnaeus), P.

subopacus Thomson, Hylesinus crenatus (Fabricius), H. oleiperda (Fabricius), Leperesinus

fraxini (Panzer), Hylastinus obscurus (Marsham), H. fankhauseri (Reitter), Xylechinus pilosus

(Ratzeburg), Pteleobius vittatus (Fabricius), P. kraatzi (Eichhoff), Phloeosinus thujae (Perris),

Hypoborus ficus Erichson, Liparthrum mori Aube, L. genistae Aube, Crypturgus cinereus

(Herbst), C. hispidulus Thomson, C. pusillus (Gyllenhal), Dryocoetes autographus

(Ratzeburg), D. villosus (Fabricius), D. alni (Georg), Xylocleptes bispinus (Duftschmid),

Cryphalus piceae (Ratzeburg), C. saltuarius Weise, C. abietis (Ratzeburg), C. intermedius

Ferrari, Ernoporus fagi (Fabricius), E. caucasicus (Lindemann), E. tiliae (Panzer),

Pityophthorus pityographus (Ratzeburg), P. lichtensteini (Ratzeburg), P. carniolicus

Wichmann, P. balcanicus Pfeffer, Taphrorychus bicolor (Herbst), T. alni (Pfeffer), T. villifrons

(Dufour), Pityogenes chalcographus (Linnaeus), P. trepanatus (Nördlinger), P. bidentatus

(Herbst), P. quadridens (Hartig), P. bistridentatus (Eichhoff), P. conjunctus (Reitter), P.

calcaratus (Eichhoff), Pityokteines curvidens (Germar), P. spinidens (Reitter), P. vorontzowi

(Jacobson), Orthotomicus suturalis (Gyllenhal), O. laricis (Fabricius), O. proximus

(Eichhoff), O. erosus (Wollaston), Ips acuminatus (Gyllenhal), I. typographus (Linnaeus), I.

amitinus (Eichhoff), I. cembrae (Heer), I. sexdentatus (Börner), Xyleborus dispar (Fabricius),

X. saxesenii (Ratzeburg), X. monographus (Fabricius), X. pfeilii (Ratzeburg), X. dryographus

(Ratzeburg), X. germanus Blandford, Xyloterus domesticus (Linnaeus), X. signatus (Fabricius),

X. lineatus (Olivier).

Thus, our data show that 57% of European species of the family Scolytidae are currently extant in

Slovenia. However, we expect closer to 120 species to be eventually identified in Slovenia according

to data in the literature (Jelínek 1993; Pfeffer 1995).

Bark Beetles (Scolytidae, Coleoptera) in Slovenia with Special Regard

to Species in Burnt Pine Forests

Maja Jurc

University of Ljubljana, Biotechnical Faculty, Department of Forestry and Renewable

 Forest Resources,Večna pot 83, 1001 Ljubljana, Slovenia
158 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Dendroctonus micans was first recorded in the Gspan collection and later found on location in

Podbrezje, Gorenjska region, 1973; it was detected in a gradation in a spruce monoculture near

Ormož (northwest part of Slovenia), 2000. In 2001 the beetle was found in 24 small groups (1 to 5

trees) of spruce trees, equal to approximately 80 m3

 of wood when the dying trees were cut down.

Bark beetles on fir (Pityokteines spinidens, P. curvidens, Cryphalus piceae, Pityokteines vorontzowi) have

only been found in a few locations throughout the country in recent years. In 2002, these beetles,

combined with the drought from the previous year, caused large gradations in several regions in the

central and particularly the southern (Kočevje region) parts of Slovenia. By 1. 7. 2002, about 36,000

m3

 of fir and 20,000 m3 of spruce (spruce death was caused by Ips typographus and Pityogenes

chalcographus) had been cut in the Ko ́evje region.

Species of Bark Beetles in the Burnt Pine Forests of the Kras Region

Within the framework of the project “Forests Fires in Slovenia” (1998-2001, financed by the

Ministry of Science and Technology and the Ministry of Defence), we studied the abiotic (soil) and

biotic (succession of vegetation, nourishment of some herbivores, entomofauna) parameters at chosen

locations in limestone and flich regions of Kras. A study of the impact of fires on the insects in trunks

in burnt-out areas of Austrian pine plantations (Pinus nigra Arn.) was carried out in the Kras region

from 1999 to 2001. The work was performed in three locations differing from one another in terms

of soil condition, size of burnt areas, as well as in the type and duration of burning.

Methods

We collected various species of insects at each location, at three times during the year (May, June/July,

September) from under a 50 x 50 cm bark patch at breast height from five Austrian pine trees chosen

at random. A Shannon –Wiener Diversity Index was used in order to demonstrate and explain the

diversity of the insects collected at the different experimental locations.

Locations

P1. Mlave: August 2000, over an area of 2.4 ha, crown fire, vegetation at location: Austrian pine

forest – Seslerio autumnalis-Pinetum nigrae.

P2. Kojnik: April 1998, over an area of 46 ha, characterized by a ground and crown fire, pastures as

well as Austrian pine forest and thermophilic deciduous trees.

P3. Podgovci: August 1998, over an area of 7.53 ha, ground fire, Austrian pine forest –Seslerio

autumnalis-Pinetum nigrae.

Results

We collected a total of 1590 specimens from the family Scolytidae. The identified species are listed in

Table 1.

The highest index of entomofauna diversity was found in the youngest burnt area while the lowest

index was found in the oldest burnt area. We can conclude that the most suitable habitat for the

species found occurs on freshly damaged trees, while aging and dried-out material served as less

suitable habitats for bark beetles.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 159

References Cited

Grüne, S. 1979. Handbuch zur Bestimmung der europäischen Borkenkäfer.- Hannover, M. & H.

Schaper: 182 p.

Jelínek, J. 1993. Check-list of Czechoslovak Insects, IV (Coleoptera).- Folia Heyrovskyana,

Supplementum 1, Praha, 172 p.

Pfeffer, A. 1995. Zentral- und westpaläarktische Borken- und Kernkäfer (Coleoptera: Scolytidae,

Platypodidae).- Basel, Pro Entomologia, 310 p.

Table 1.—Survey of insects collected in pine monocultures in trunks of declining

and dead Austrian pine trees in Kojnik (P1), Podgovci (P2) in Mlave (P3) from

1999 to 2001.

Family SCOLYTIDAE P1 P2 P3 TOTAL

Ips sexdentatus (Börner) 964 7 220 1191

Ips acuminatus (Gyllenhal) 8 8

Orthotomicus laricis (Fabricius) 158 7 7 169

Orthotomicus suturalis (Gyllenhal) 2 2

Pityogenes chalcographus (Linnaeus) 131 131

Pityogenes trepanatus (Nördlinger) 6 6

Pityogenes bistridentatus (Eichhoff) 45 45

Tomicus minor (Hartig) 3 2 5

Tomicus piniperda (Linnaeus) 2 2

Hylastes ater (Paykull) 14 1 15

Hylastes Erichson, (two species) 12 4 16

Total 1282 31 277 1590
160 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

The methodology for predicting phenological events are useful for predicting the seasonal

development of insects in the current year, for analyzing terms and rate variation of insect population

development in different years, and for comparing different geographical and ecological insect

populations after terms and rate of different stages of seasonal development.

A mathematical sense of the proposed approach is in the determination of such period (n days) in the

year temperature course, the average temperature of which allows to complete development of a

particular stage of insect for the same n days. The values of n are determined by graphical solution of

the system of two or more empirical equations, where one equation characterizes the heat resources of

a geographical region and the others define the heat demands of biological objects (Podolskij 1967)

The heat requirements of insects are represented as curves that show the dependency of certain stage

of instar development duration (n days) on the mean air temperature during the period of this

development (T). Such curves are called “phonological” curves.

The basis of such curves are data on the developmental dates for objects obtained at constant

temperatures in the laboratory as well as data obtained from field investigations or from the literature

(Meshkova 2001a,b,c,d). Datasets for many years or for different points were plotted in the graphs

and trend lines n=f (T) were constructed (Fig.1,2).

Heat resources of a region were represented in such a way that it was possible to determine the mean

air temperature for any time interval in a season. The net of heat resources consists of lines; every line

is marked by the mean date for a respective period (for example, <<15.IV>>, <<25.VI>>). Every line

consists of points whose coordinates are determined from values for 10 day periods. To build the net

of heat resources, auxiliary tables were calculated for different geographical regions from data on

mean air temperature over many years

(Meshkova 2001 b). If necessary,

intermediate lines can be built by

graphical or analytical means.

For a graphical solution of the system

of equations that describe heat

demands of insects and heat

availability, the net of heat resources

and the phenological curve must be

plotted at the same coordinates. One

must find the line of heat resources

that starts from the beginning date of

a given stage and the point of its

intersection with the phenological

curve for that stage. Then the ordinate

of the intersection point is equal to

the number of days which are

necessary for this stage to complete its

development. The results of such

estimations are represented as phenological calendars for a region (Meshkova 2001a, b, c, d).

It is known that air temperature growth temp depends on latitude and longitude. It transits over 0°C

in Lviv (49°49’ N, 23°57’E) on March 14 and in Kharkiv (49°58’ N, 36°08’E) on March 22, but it

Phenological Prediction of Forest Pest-Defoliators

Valentina Meshkova

Ukrainian Research Institute of Forestry & Forest Melioration

Figure 1.—Phenological curves for eggs development: 1 – Lymantria

dispar L.; 2 – Operophthera brumata L.; 3 – Tortrix viridana L. 4 –

Archips crataegana Hb.















       	 
      









   
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 161

transits over 10°C 6 days earlier in Kharkiv (24.IV), than in Lviv (30.IV). If winter moth eggs begin

development on March 15, then larvae will hatch 42 days later in the Crimea and 57 days later in

Kharkiv. If eggs begin development on April 15, then larvae will hatch almost simultaneously (two

days difference) in Lviv and Kharkiv.

Based on analysis of data from many years, winter moth egg development begins on April 1 in

Simferopol (44°41’N, 34°08’E) and larvae would appear there in 30 days or on May 1, on May 5, in

Lviv, and on May 9 in Kharkiv. According to calculations, then larvae will pupate 24 days after April

1, that being May 25 in Simferopol, 25 days after May 5, or May 30 in Lviv, 23 days after May 9, or

June 1 in Kharkiv.

However the suggested method can be used only for predicting insect development during the first

part of the summer; after the solstice, the role of photoperiod in their development becomes more

important. For example, the timing of winter moth swarming does not depend on the completion of

larval feeding, but rather it coincides with the end of the vegetation period at a given point.

Therefore, winter moth swarming is observed earlier in the northern regions and later in the southern

regions.

References Cited

Meshkova, V. 2001a. Phenological prognosis of Neodiprion sertifer Geoffr. for different zones of

Ukraine. Problems of ecology and forest use in Polissya of Ukraine. Zhitomir: Volyn. V.2 (8):

125–130 [In Ukrainian].

Meshkova, V. 2001b. Phenological prognosis of pine defoliators taking into account heat resources

of region. Forestry & Forest melioration. Kharkiv. V.99: 112–120 [In Ukrainian].

Meshkova, V. 2001c. Prediction of the seasonal development of the gold-tail moth Euproctis

chrysorrhoea L.. Proceedings of National Agricultural University / V.46: 164–171 [In Ukrainian].

Meshkova, V. 2001d. Prediction of Tortrix viridana L. seasonal development. Forestry & Forest

melioration. Kharkiv V.100: 108–116 [In Ukrainian].

Podolskij, A.S. 1967. The new approach in phenological prediction. Nauka, Moscow. 232 p. [In

Russian].

Figure 2.—Phenological curves for larvae development: 1 – Neodiprion

sertifer Geoffr.; 2 – Operophthera brumata L.; 3 – Panolis flammea L.;

4 – Archips crataegana Hb.; 5 – Euproctis chrysorrhoea L.

















       	   









   
162 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

Research has been carried out during the past six years (1996-2001), to record the occurrence of wind

damage in resinous stands and to monitor the evolution of pest infestations during this period. The

level of pest attack has become moderate over time and depended on different types of damaged

wood material (cut, broken and fallen trees). We also reported about the incidence of infested

standing trees in correlation with the quantity of windthrown wood.

Introduction

A windfall of vast proportions occurred on November 5-6, 1995, that severely affected Romanian

forest stands in the following counties: Covasna, Harghita, Mureș, and Bistriţa from Oriental

Carpathians (Simionescu et al., 2001). Research was carried out over the years after windfall, and has

been conducted in experimental plots characterized by the presence of a variety of stands and

different environmental conditions. The purpose of these investigations was to study the evolution

and the dynamics of pests attacking both windthrown and standing trees.

Materials and Methods

A large number of experimental plots were located in areas affected by windfall, where we registered

damaged trees (fallen, broken, cut and pruned trees). These trees were analyzed in order to find out

the diversity of bark and wood boring insects, the intensity of infestation, and their developmental

stages. Relying on these data, we estimated the frequency of infestation over time, and recommended

appropriate control measures and the opportune time for their application.

Results

The evolution of infested woody material over time. In the majority of circumstances, spruce trees

were infested at a high level. The main pests which infested damaged trees were the following: Ips

typographus, Pityogenes chalcographus, Ips amitinus, Polygraphus poligraphus, Trypodendron lineatum,

Hylurgops palliatus, Tetropium castaneum, Monochamus sutor, Urocerus gigas, Orthotomicus suturalis. In

the first year after the windfall (1996), the intensity of insect attack was generally low. Intensive

infestations were observed only in areas where bark beetle outbreaks were recorded in the past.

During the next years (1997-2000) the infestation increased significantly, and as a result in 2000 we

registered high and very high levels of pest attacks in all damaged areas (Fig. 1).

The influence of damage type on infestations

In all damaged areas, about 40% of the trees were windthrown and 60% were broken at the base of

trunks. The windthrown trees were still connected with the soil, and continued to vegetate during the

next 1-3 years after the windfall. During this period, the frequency of infestation by pests was 34% in

1996, 61% in 1997, and 5% in 1998. Over 90% of the broken and fallen trees were infested in

1996, and less than 5% in 1997.

The period between the occurrence of damages and the time that trees were attacked varied in

relationship with the type of tree damage – windthrown, broken or cut trees (Table 1). Cut and

pruned trees were infested within 1-2 months, broken at the basal part of stem and fallen trees were

The Frequency and Intensity of Bark Beetle Infestations Recorded in

Romanian Forests Affected by Windfall in 1995

V. Mihalciuc1, A. Danci2, M. Bujilă1 and D. Chira2

1

Forest Research and Management Institute Brasov, Romania

2

Simon Fraser University Vancouver, Canada
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 163

infested after 6-7 months, and windthrown trees were infested within 7-18 months after windfall.

Because of these results, we strongly recommend that damaged wood material should be remover

before infestation by bark beetle species can occur.

The infestation of standing trees after the windfall

We established a correlation between the quantity of damaged wood material recorded in 1995 and

the percentage of infested standing trees that were recorded between 1996-1998. The large number of

fallen trees favored bark beetle outbreaks. This was reflected indirectly by the increased number of

standing trees that were infested. This situation was especially evident in the Ranger Districts of

Covasna and Comandău where the volume of damaged trees was the largest.

The highest number of infested standing trees occurred four years after the calamity - 8,300 trees in

Ranger District Covasna and 14,548 trees in Ranger District Comandău. In 2000, the number of

infested standing trees was reduced significantly as a result of the protection measures which were

implemented in the damaged forests during 1996-1999 (Mihalciuc et al. 2001).

Figure 1.—Distribution of the intensity of bark beetle infestation after the November

5, 1995 windfall (Counties of Covasna, Harghita, Mureş, and Bistri a; 1: very low, 2:

low, 3: medium, 4: high, 5: very high)

1996

34%

28%

24%

14% 0

19990

0

5%

28%

67%

1997

0 11%

24%

41%

24%

2000

0 21%

79%

1998

0 6%

27%

67%

20010

0

20%

60% 20%

1 2 3 4 5

Table 1.—The period (months) between damage and stem infestation (County of Covasna,

Mureș, Bistriţa, Brașov, Prahova, Sibiu; 1995-2001)

Type of damage Main pests

It Ia Pc Tl Hp Hg Os Ms Ug

Windthrown trees 14.7 15.0 17.9 14.2 16.2 14.7 13.5 7.5 8.5

Trees broken by wind 7.1 7.0 7.3 6.2 -----

from the basal part of stem

Trees with basal stem 1.2 1.7 1.4 2.1 2.6 - 1.6 - -

sectioned (cut), and pruned

It: Ips typographus; Ia: Ips amitinus; Pc: Pityogenes chalchographus; Tl: Trypodendron lineatum;

Hp: Hylurgos palliatus; Hg: Hylurgos glabratus; Os: Orthotomicus suturalis; Ms: Monochamus sutor;

Ug: Urocerus gigas.
164 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Conclusions

1. The level of infestation of damaged trees and the number of infested standing trees were highest

3-5 years after the windthrow of 1995.

2. In the first year after the damage (1996), over 90% of the trees broken at the basal part of stem

were infested; the windthrown trees were infested during the next two years after the windfall

(1996-1997); at high altitude and on slopes with intermediate exposure, the infestation took

place beginning in 1998.

3. The larger volume of damaged wood material was favorable to the development of higher bark

beetle populations; however, annual control measures have reduced the severity of pest

outbreaks.

References Cited

Simionescu A., V. Mihalciuc, A. Vlăduleasa, O. Badea, T. Fulicea, M. Liţescu, A. Danci, M.

Bârca, S. Popescu, and P. Enescu. 2001. The health state of Romanian forest between 1986-

2000. Ed. Musatinii, Suceava (in Romanian).

Mihalciuc V. A. Danci, N. Olenici, and A. Vlăduleasa. 2001. Sanitary state of resinous stands from

Romania and the protection measures applied in the 1990-2000 period. In: M. Knizek., B.

Forster, W. Grodzki (eds.). Methodology of Forest Insect and Disease Survey in Central Europe.

Proceedings of the Fourth Workshop of the IUFRO WP 7.03.10, September 17-20, 2001, Praha,

Czech Rep. J. For. Sci., 47, Special Issue 2: 136-138.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 165

Abstract

The mountain pine beetle, Dendroctonus ponderosae Hopkins, is the most important bark beetle

associated with ponderosa pine, Pinus ponderosae Lawson, in Colorado. Periodic outbreaks of this

insect have caused extensive tree mortality in the past. No data are available which relates stand

conditions to the susceptibility of trees or stands to this insect in Colorado. In 1998, we initiated a

study with the objective of developing a probability of infestation model and to examine the use of

basal area increments as a predictor of bark beetle susceptibility. We established 35 clusters of fixed

radius plots 0.04 ha in size. One plot was infested by mountain pine beetle while the other three were

baseline plots. Ponderosa pine forests in Colorado are clumped in nature so by having more baseline

plots we could reduce some of the variation associated with clumped ecosystems. We collected

mensurational data from all the plots and collected cores from all trees at least 15.2 cm in diameter at

breast height. All cores were sanded, dated, and tree rings were measured. A classification tree model

was constructed which indicated that the probability of infestation was 0.7 when ponderosa pine

basal area was equal to or greater than 17.1 m2

/ha, and 0.21 when ponderosa pine basal area was less

than 17.1 m2

/ha. Tree ring records from individual trees indicated that a reduction in basal area

occurred consistently in mountain pine beetle-killed trees since the 1900s. At the plot level, the mean

difference in basal area increments between infested and baseline plots from the 1920s to the 1980s is

essentially zero. After that, infested plots exhibit larger reductions in basal area increments. The

observed reduction in basal area increments at both the tree and plot level in infested plots is

associated with increased basal area. Our data agree with other studies that have implicated reduced

growth rates with increase susceptibility to bark beetles. Additional data analysis is underway to

determine if there is a threshold of basal area increments at which ponderosa pine trees become more

susceptible to mountain pine beetle.

Dendrochronological Analysis of Trees and Stands Attacked by

Dendroctonus ponderosae in Colorado

José F. Negrón and John Popp

USDA Forest Service, Rocky Mountain Research Station

 240 West Prospect, Fort Collins, CO 80526

 e-mail: jnegron@fs.fed.us, voice: 970-498-1252 fax: 970-498-1314
166 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

Pipe traps (IBL-4) are used in Polish coniferous plantations to monitor and control the pine weevil

(Hylobius abietis L.). This study was conducted in a one-year old pine plantation established on a

reforested clear-cut area in order to evaluate the impact of these traps on non-target insects.

Evaluation of the catches indicated that species of Carabidae were the most frequently captured group

of non-target insects.

Key Words: Hylobius abietis, IBL-4 traps, non-target insects

Weevils of the genus Hylobius (Coleoptera: Curculionidae) are particularly important pests in

European coniferous plantations. In Poland, the pine weevil (Hylobius abietis L.) has become the

most harmful pest of 1-3-year old coniferous crops. To control the pine weevil, pipe traps IBL-4

baited with a mixture of a-pinene and ethanol (Hylodor R)were placed into coniferous plantations in

order to monitor and control pine weevil populations. Hylodor R-baited traps often capture nontarget insects in addition to pine weevils. This study was conducted to evaluate the species and

numbers of non-target insects that are captured in pine weevil IBL-4 traps.

Materials and Methods

The observations were carried out in 1998 on one-year old plantation (1.5 ha) of Scots pine (Pinus

silvestris L.) and Norway spruce (Picea abies L.) in the Celestynow Forest District (Central Poland).

The plantation was established on a clear-cut area that resulted from harvesting a 100 year old Scots

pine stand. In April, 15 IBL-4 traps were installed linearly (20 m apart) in the middle of the

plantation. Captured insects were collected biweekly during the period April-September and

identified as to species and family.

Results

IBL-4 traps caught in total 2839 the pine weevils, averaging from 1.18 ± 1.03 to 96.18 ± 15.83

beetles/trap and 284 non-target insects of 20 species that belonged to nine families (Table 1). The

average number of non-target insects caught per trap was between 4 ± 1.67 and 8.82 ± 2.25

individuals.

The highest number of insects captured belonged to the family Carabidae (12 species from genera:

Carabus, Pterostichus and Harpalus). Other individual species captured were from the families

Anobiidae, Byrrhidae, Cerambycidae, Cicindelidae, Dermestidae, Elateridae, Geotrupidae, Gryllidae,

Lucanidae, Nitidulidae, Silphidae and Staphilinidae.

Based on results obtained it appears that the most abundant group of non-target insects captured in

IBL-4 traps resulted from their accidental walking into the traps or due to their search for shelter.

This group includes species from the Carabidae and species from the Anobiidae, Byrrhidae, Elateridae,

Gryllidae, Lucanidae and Staphylinidae. Representatives from the Dermestidae and Silphidae feeding

on dead insects were probably attracted to the traps by the odor from decomposing insects inside the

traps.

Insects in IBL-4 Pine Weevil Traps

I. Skrzecz

Forest Research Institute, Bitwy Warszawskiej 1920 r. no. 3, 00-973 Warsaw,

 e-mail: I.Skrzecz@ibles.waw.pl
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 167

Table 1.—Number of non-target insects in IBL-4 traps

Species Number of insects

Anobiidae:

Anobium punctatum 1

Byrrhidae:

Byrrhus pilula 1

Carabidae:

Agonum sexpunctatum 3

Carabus arcensis 166

Carabus hortensis 22

Carabus violaceus 1

Chlenius nitidulus 1

Harpalus latus 1

Harpalus rufipes 15

Pterostichus angustatus 10

Pterostichus caerulescens 2

Pterostichus niger 20

Pterostichus oblongopunctatus 8

Pterostichus rufipes 2

Dermestidae:

Dermestes laniarius 2

Elateridae:

Melanotus erythropus 1

Gryllidae:

Gryllus campestris 18

Lucanidae:

Platycerus caprea 1

Silphidae:

Necrophorus vespillo 1

Staphylinidae:

Staphylinus erythropterus 8
168 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

Beginning in 1996, populations of Ips typographus in the Friuli-Venezia Giulia region (NE Italy) have

been monitored by using pheromone traps. Preliminary analysis of the data (1996-2001) reveals some

interesting information:

1) the flight activity of Ips typographus is very extended and occurs over a period of four months

(mid May until August)

2) the outbreak which began in 1996 has declined gradually over time as shown by lower levels of

both insect captures and damage

3) there is a high correlation between spring captures (May-June) and total captures (MayAugust) and between spring captures and damage. The high correlation between spring

captures and damage allows us to determine a reliable risk threshold (about 5,000 beetles/trap

in spring), and at the same time reduce the period of monitoring. Pheromone traps are useful

for studying both the biology and population dynamics of Ips typographus populations.

Key Words: Ips typographus, monitoring, pheromone traps, damage forecast

Most studies that involve the monitoring of populations of Ips typographus (L). (Coleoptera

Scolytidae) have been carried out in central and northern Europe where the winters are long and cold

and flight activity begins quite late in the season (June-July); therefore the short summer allows

completion of only one generation per year and damage to spruce stands is not always severe.

However, in southern European countries, I. typographus attacks host trees early in the spring (AprilMay) and very often two generations are completed; consequently spruce trees which survive the

attacks of the first generation can still be attacked and killed by emerging second generation adults.

In this paper we summarize some data obtained from monitoring I. typographus over a period of six

years and discuss how pheromone trap data might be used to forecast damage caused by this species.

Materials and Methods

Beginning in 1996, populations of I. typographus have been monitored permanently in the main

spruce forests of the Friuli-Venezia Giulia (north-eastern Italy) by using ca 30 pheromone traps

(Theysohn® slot-trap) baited with methyl-butenil, cis-verbenol and ips-dienol. The traps are

installed and baited each year at the end of April and are checked weekly at which time all beetles

captured are determined and counted. All pheromone dispensers are replaced after two months. The

trials last until the first half of September and data are reported as mean captures per trap. At the

same time, damage caused by I. typographus is recorded from field observations carried out over an

area of 300 m around the traps beginning on the 1st of May (initiation of I. typographus flight) and

continuing until April 30 of the following year.

Results

Captures observed in 1996 are higher than those of the following years (ANOVA, d.f.= 1; 5, F=8.43,

P<0.001; Tukey’s test, P<0.01) (Fig. 1). The volume of timber lost between 1996-2001 (Fig. 2) shows

the same trend as the captures (Fig. 1). In addition, there is a significant correlation between the

captures observed during the entire monitoring period (May-September) and those obtained in

Ips typographus (L.) (Coleoptera: Scolytidae) in Southeastern Alps:

Results of a Six-Year-Long Monitoring Program

F. Stergulc1 and M. Faccoli2

1

Department of Plant Protection, University of Udine, Italy

2

Department of Environmental Agronomy and Crop Production, University of Padua, Italy
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 169

	
	































    	    

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spring (May-June) (d.f.= 1; 63, F=1400.95, P<0.001, R2=0.957) (Fig. 3). Similarly, the spring catches

are correlated with the total annual damage (d.f.= 1; 5, F=157.71, P<0.001, R2

=0.975) (Fig. 4).

Discussion

Both mean captures and damage declined considerably over time from 1996 to 2001 (Fig. 1 and 2).

In northern Italy, I. typographus has a very long period of flight activity beginning early in May and

ending at the beginning of September. Therefore, in order to follow the entire spring and summer

activities of I. typographus, which covers more than 4 months, it was necessary to replace the

pheromone dispensers at the middle of the spring monitoring period (the first week of July).

Unfortunately, monitoring data are available only at the end of summer by which time the flight

period of the beetle has concluded and most of the damage has already occurred. Consequently, early

forecasts about the volume of timber lost during the season are very important in determining the

need for applying useful and prompt control strategies. The correlation found in the present work

between spring captures (May-June) and total captures (May-August) (Fig. 3) and between spring

captures and damage (Fig. 4), provide us with an opportunity to assess in advance the risk of future

outbreaks and the time necessary to apply pest controls. Based on our results, monitoring could be

terminated after two months (at the end of June), which would reduce the overall costs; and because

of the good correlation between mean captures and the damage observed, it might also be possible to

determine a “catch threshold ”along with a relative “damage threshold”, which would help us to

decide about the need for additional control measures. In Friuli – Venezia Giulia, by using a

threshold of around 5,000 insects per trap during the spring monitoring period, we would expect

that the damage in the monitored area would be lower than 100 m3

 (Fig. 4). In northern and central

European spruce plantations, the kind of silvicultural and the orographical features might tolerate

higher densities of I. typographus populations, however in the Alps, control would have to be more

intensive because the expansions of severe outbreaks is more difficult to confine on the accentuated

slopes where there is a less extensive network of forest roads.

Figure 1.—Mean captures over the last six years. Different Figure 2.—Damage observed in the last six years.

letters correspond to statistical differences (P<0.01).

Figure 3.—Correlation between spring and total captures.















     

























	





































 

































  	   



























	



























	



































 
  
  
  
 

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Figure 4.—Correlation between spring captures and damage.
170 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Black locust (Robinia pseudoacacia) plays an important role in Hungarian forestry and represents

21.6% of the total forested area (370 thousand hectares); approximately 19.2% of the area in

Hungary is forested. Black locust forests have increased by more than one percent over the last 5 years

demonstrating that it is a preferred tree species particularly among the owners of private forests (45%

of Hungarian forests are privately owned). Consequently, there is a lot of concern about the health of

locust stands throughout the country. In order to monitor the trend in locust stands, we established a

network of 20 sample plots containing 2,400 individually marked trees. These trees are assessed in

detail twice each year. In addition, we obtain data on tree health from the reports of the Forest Health

Monitoring Network

There are relatively few pest species known to feed on black locust, however in the last few decades,

new pest species have been introduced accidentally to Europe from North America where black

locust also occurs. In the past 100 years, 11 new species have been introduced accidentally to the

Carpathian basin and have become pests; the majority of them originated from North America. In

the last 20 years, two species of leaf miners (Parectopa robiniella and Phyllonorycter robiniella) have

been established as pests of R. pseudoacacia thus destroying its reputation as a relatively “pest free”

species.

Based on our present knowledge, the main groups of organisms that attack black locust are as follows:

Viruses: three species

Nematodes: seven species

Insects: 42 species

Fungi: 30 species

Vertebrates: nine species

Parasitic plants: one species

Biotic Agents that Damage Black Locust in Hungary

József Tóth

Forest Research Institute, Department of Forest Protection, Budapest, Hungary
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 171

Abstract

Numbers of pine shoot beetles Blastophagus piniperda and B. minor trapped in pheromone traps

within a pine beauty moth (Panolis flammea) outbreak area were significantly greater in zones with

total 100% defoliation (26.8±10.4 and 5.8±2.0 beetle/trap, both species respectively) as compared to

undefoliated stands (1.8±1.3 and 1.4±1.0) and zones with moderate 50% (3.7±1.5 and 3.3±1.2) and

heavy 75% defoliation (6.1±2.4 and 1.8±0.9, respectively). Peak flight of Blastophagus piniperda was

observed in the last part of April, whereas Blastophagus minor was trapped at constant but small

numbers for approximately a month up until the middle of May.

Keywords: Blastophagus piniperda, Blastophagus minor, pheromone traps, defoliation, Panolis flammea

Introduction

An outbreak of the pine beauty moth (Panolis flammea Schiff.) occurred recently in southern

Lithuania pine stands and covered 44800 ha in 2000; an area of 4000 ha was totally defoliated. Pine

trees can usually withstand a single total defoliation, however such stressed forests provide an

opportunity for attacks by bark beetles and population expansion, which can result in a high risk for

tree mortality. The key management option in Lithuania is to eliminate trees that are stressed by

defoliation or freshly attacked by bark beetles and by using selective or clear cutting. However

residual stands can provide an additional food source for pine bark beetles thus reducing the success

of forest sanitation measures

The objective of this study was to assess the population levels and to determine the flight periodicity

of the common (Blastophagus piniperda L.) and lesser (B. minor Hart.) pine shoot beetles in forests

that suffered different degrees of defoliation. This will provide us with a rationale for determining the

best management options for reducing the risk of attacks by bark beetles on residual living trees.

Material and Methods

Pine shoot beetles were trapped in barrier traps made of transparent polyethylene film and baited

with Tomodor® commercial lure (Z.D. Chemipan, Poland). Pheromone traps were placed in the

clear cuts within pine beauty moth outbreak areas in southern Lithuania. Thirty-five traps were

placed at least 50 m apart from each other and 50 m from the edge of the stand defoliated by the

pine beauty moth. The study was conducted in zones with four damage categories: undamaged

control, moderate (50% defoliation), significant (75% defoliation) and heavy (100% defoliation).

Traps were set out on 4 April and checked every 10-14 days for a period of four months. Differences

among damage zones were tested using Student’s T-test (Campbell 1989).

Results

The study was conducted in the year following pine beauty moth damage. Population levels of pine

shoot beetles appeared to be low (Table 1) on all experimental sites. Captures of B. piniperda ranged

from 1.8±1.3 beetles per trap in control sites to 26.8±10.4 in totally defoliated stands. Captures of B.

minor were much lower – from 1.4±1.0 to 5.8±2.0 beetles/trap during the whole season.

Pine Shoot Beetles Blastophagus piniperda L. and B.minor Hart. Associated

with Outbreaks of the Pine Beauty Moth (Panolis flammea Schiff.)

Skirmantas Vaivada

Lithuanian Forest Research Institute
172 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Even at these low population levels, bark beetle number were related to the degree of defoliation on

the study sites. Numbers of both species were significantly higher in traps located in totally (100%)

defoliated stands as compared to captures in control and partially defoliated (50-75%) stands. There

was no significant difference in the numbers of pine shoot beetles captured in control stands vs.

stands that were partially defoliated although captures of B. piniperda clearly showed a trend to

increase with increasing damage.

In 2000, pine shoot beetles initiated flight in the middle of April. Seasonal periodicity of bark beetle

captures averaged over all levels of defoliation indicate that peak flight of B. piniperda occurred

during the last 10 days of April and declined rapidly in May, while B. minor was captured at a

constant but smaller number for approximately a month, and ended around the 20th of May. This

flight pattern in 2000 differed significantly from the long-term average; in Lithuania, B. piniperda is

reported to initiate flight in March and B. minor begins flight activity a few weeks later (Valenta

2000).

Conclusions

• Numbers of pine shoot beetles B. piniperda L. and B. minor Hart. captured in

pheromone traps within pine beauty moth outbreak areas were significantly greater in zones

with 100% defoliation (26.8±10.4 and 5.8±2.0 beetle/trap, both species respectively) as

compared to undamaged stands (1.8±1.3 and 1.4±1.0) and zones with moderate 50% (3.7±1.5

and 3.3±1.2) and heavy 75% defoliation (6.1±2.4 and 1.8±0.9, respectively).

• Peak flight of B. piniperda was observed around the last week of April, whereas B. minor Hart

was captured at a constant but smaller number for approximately a month up until the middle

of May.

References Cited

Campbell, R.C. 1989. Statistics for biologists. Third edition. Cambridge University Press.

Anonymous. 2000. Annual report on sanitary condition of state forests. Forest Protection Station,

Kaunas. p.16-38.

Valenta, V. 2000. Bark beetles. In: Manual of forest protection (ed. A. Ziogas). Kaunas, Lutute ̇.

p. 135-163.

Table 1.—Mean number of captured beetles/trap*

Defoliation Blastophagus minor Blastophagus piniperda

100% 5.8±2.0 a 26.8±10.4 a

75% 1.8±0.9 b 6.1± 2.4 b

50% 3.3±1.2 b 3.7± 1.5 b

0% 1.4±1.0 b 1.8± 1.3 b

*numbers in the column, followed by same letter, did not significantly differ when

tested with Student-t
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 173

Abstract

Intensive logging of pine and spruce forests in Estonia has led to a rapid increase in the populations

of some insect species. A survey using ground traps baited with a blend of turpentine and ethanol

resulted in the recovery of large numbers of the large pine weevil, Hylobius abietis, as well as bark

beetles of the genus Hylastes. During an 11-year study (1990-2000) carried out in reforestation areas

of Estonia, a total of 61,721 insect specimens were captured. The percentages of trapped insects were

as follows: Hylobius abietis 65.6%, Hylobius pinastri 0.5%, Hylastes brunneus 17.8%, Hylastes opacus

5.3%, Hylastes cunicularius 0.5%, and all other insect species 10.3%. In newly created clear cuttings,

an average of 1124 individuals of Hylobius abietis were caught per trap in 1999. The associated bark

beetle species Hylastes brunneus and Hylastes opacus were more abundant in the second year after

felling; the mean numbers of individuals caught per trap were 309 and 94, respectively.

Key Words: Hylobius abietis, Hylastes, logging, pitfall traps, clear-cutting, Estonia

The large pine weevil, Hylobius abietis (L.) (Coleoptera: Curculionidae), is the major insect pest

affecting reforestation (Leather et al. 1999). Its abundance is strongly dependent on the intensity of

forest cutting because this species utilizes stumps and roots of recently felled conifer trees as suitable

breeding sites.

In Estonia, the extent of forest exploitation increased considerably during recent years. In 2000, the

gross felling volume was 12.7 million solid cubic metres, i.e. about four times as much as in the early

1990s. The total area of felling activity was 28,800 hectares, of which 26,900 ha was attributed to

clear cuttings (Adermann 2002). Of the volume felled, the prevailing tree species was Norway spruce,

which accounted for 46%, followed by Scots pine (21%) and birch (17%). Intensive logging of pine

and spruce forests has led to a rapid increase in populations of the pine weevil.

Several methods for using baited pitfall traps have been developed for monitoring H. abietis

populations. A standardized method for trapping pine weevils, using pitfall traps baited with alphapinene and ethanol, was developed in Sweden (Nordlander 1987). Different modifications of this

trap have been applied in Europe (Zumr and Stary 1993, Örlander et al. 1997) and have been used

in North America to investigate related native species (Raffa and Hunt 1988, Rieske and Raffa 1999).

Some investigations using baited ground traps have been conducted in Estonia (Voolma 2000, 2001,

Voolma et al. 2001). In this study, trapping was used for estimating the relative size of the

populations of H. abietis and associated bark beetle species of the genus Hylastes. Since some species

of bark beetles, particularly Hylastes brunneus and Hylastes opacus respond to the same host volatiles as

H. abietis, the same trap can be also used for monitoring these species.

Materials and Methods

Study sites

The study was conducted in 1990–2000 in an intensively managed forest area in the forest district of

Räpina, Estonia (58°09' N, 27°08' E). Clear-cuttings of former pine-dominated stands (90% of

Pinus sylvestris and 10% of Picea abies) on dry sandy soil were selected as the study sites. The clearcuttings were reforested by sowing Scots pine in the first season following felling.

Survey of Hylobius abietis (L.) and Associated Species in

Reforestation Areas Using Baited Pitfall Traps

Kaljo Voolma

Forest Research Institute, Estonian Agricultural University, F.R. Kreutzwaldi 5,

 51014 Tartu, Estonia; e-mail: kvoolma@eau.ee
174 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

The traps

The traps used in this study have been described in detail in our previous publications (Voolma

2001, Voolma et al. 2001). The ground trap consisted of a plastic jar inserted in the ground and

filled with water to 1/3-1/2 of its volume.

The above-ground part of the trap holds a glass vial containing the bait fluid, a blend of commercial

turpentine (AS Flora, Estonia) and ethanol (1:5). To enter the trap, insects climb along the inclined

plane to the top of the trap and fall into the jar. The traps were checked usually once each week. At

each inspection, insects were collected and the baits were renewed. Most captures occurred from late

April (early May) to September. As a comparison, Swedish pitfall traps described in Nordlander

(1997) were also used in 1993-1995.

Results and Discussion

During the survey of 1990-2000, a total of 61,721 specimens were caught at the study sites. The

percentages of trapped insects were as follows: H. abietis 65.6%, Hylobius pinastri 0.5%, Hylastes

brunneus 17.8%, Hylastes opacus 5.3%, Hylastes cunicularius 0.5%, and all other insect species 10.3%.

There was no difference in captures of H. abietis in 1993-1995 between the Swedish pitfall traps and

the trap used in this study (Voolma 2000).

This trapping method enabled us to estimate the relative size of populations of H. abietis and

associated species, particularly H. brunneus and H. opacus, in felled areas and at reforestation sites. In

the study area, several clear-cut plots had been established in recent years within a range of 2-3 km;

this resulted in a rapid increase in populations of H. abietis, a species which is abundant in fresh

clear-cuts. Consequently, populations increased considerably in these clear-cuts and the average

captures per trap reached 1,124 in 1999.

Bark beetle species such as H. brunneus and H. opacus were more abundant in the second year after

felling; the mean numbers of individuals caught per trap were 309 and 94, respectively. The

abundance of H. abietis at any particular site depends largely on the temporal and spatial

arrangement of clear-cuts. Newly established clear-cuts attract dispersing pine weevils which

influences trapping results at neighbouring sites. Therefore, the abundance of H. abietis was high not

only in the first year after felling but also in subsequent years after new clearings were established in

adjacent areas. In some clear-cuts H. abietis was abundant even 6–7 years after felling (Voolma 2001).

Hylobius pinastri and Hylastes cunicularius occurred in low numbers in the study sites. In general,

these species are common in Estonia but they occur more numerously in felled areas of former spruce

forests.

Acknowledgments

The study was supported by Grant No. 4728 from the Estonian Science Foundation.

References Cited

Adermann, V. (ed.) 2002. Forests of Estonia 2001. Tallinn. (In Estonian).

Leather, S.R., K.R. Day, and A.N. Salisbury. 1999. The biology and ecology of the large pine

weevil, Hylobius abietis (Coleoptera: Curculionidae): a problem of dispersal? Bull. Entom.

Research 89(1): 3–16.

Nordlander, G. 1987. A method for trapping Hylobius abietis (L.) with a standardized bait and its

potential for forecasting seedling damage. Scand. J. For. Res. 2: 119–213.
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 175

Örlander, G., U. Nilsson, and G. Nordlander. 1997. Pine weevil abundance on clear-cutting of

different ages: a 6-year study using pitfall traps. Scand. J. For. Res. 12(3): 225–240.

Raffa, K., and D.W.A. Hunt. 1988. Use of baited pitfall traps for monitoring pales weevil, Hylobius

pales (Coleoptera: Curculionidae). Great Lakes Entomol. 21 (3): 123–125.

Rieske, L.K., and K.F. Raffa. 1999. Baited pitfall traps and evaluation of dispensing methods for

root weevils (Coleoptera, Curculionidae) in newly established pine plantations in Wisconsin. J.

Econ. Entomol. 92(2): 439–444.

Voolma, K. 2000. Comparison of two traps used for monitoring large pine weevil populations,

Hylobius abietis L. (Coleoptera: Curculionidae). Transactions of the Estonian Agricultural

University 209: 233–235.

Voolma, K. 2001. The large pine weevil, Hylobius abietis L., in the felling areas of the Räpina forest

district: a case study with baited ground traps. Metsanduslikud Uurimused 35: 172–178. (In

Estonian with English summary).

Voolma, K., I. Süda, and I. Sibul. 2001. Forest insects attracted to ground traps baited with

turpentine and ethanol on clear-cuttings. Norwegian Journal of Entomology, 48(1): 103–110.

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176 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Abstract

The objective of this research was to evaluate different methodologies for quantifying pine beauty

moth (Panolis flammea Schiff.) populations in pine stands of Southern part of Lithuania. Evaluations

were conducted in selected pine stands by assessing the following: pupae (in the litter); larvae (falling

from trees after chemical knock down); and adult insects (using pheromone traps). Analysis of

evaluation methods indicated that the populations can be assessed most accurately by using the

counts of larvae. This method is used when outbreaks occur or aerial spraying of insecticides is

needed. Assessment of pupae in the litter is the most suitable method for silvicultural purposes; the

use of pheromone traps is less precise than the other two methods.

Key words: Pine beauty moth, population, assessment

Introduction

The pine beauty moth (Panolis flammea Schiff.) is one of the most serious defoliators of pine. The

entomological and forest protection literature provides reviews of previous studies which describe

observations on this pest and methods for forecasting its abundance however they are rather

imperfect. Very often mass outbreaks are observed too late, forecasts are inaccurate, there is not

enough time to conduct control activities. Thus control measures are often ineffective and mass

outbreaks spread over thousands of hectares. The elimination of these outbreaks requires additional

expenditures, and control activities may have an adverse influence on forests and non-target

organisms.

Pine beauty moth (P. flammea Schiff.) infestations in Lithuania were increasing almost geometrically

in the 20th Century (1100 ha in 1922, 4200ha in 1953, 27000 ha in 1979, 44800 ha in 2000). The

purpose of this study was to compare methods used to evaluate populations of the pine beauty moth.

Methods

Observations were conducted in pine stands of the Druskininkai forest enterprise where the pine

beauty moth damaged up to 70-100% of needles. A 100 ha area was divided into 100 equal squares

in April, 2001. The number of pupae in the litter was determined at each point of two 0.25x1.0 m

plots placed under each of 6 trees. The pupae were grouped according to their sex, and the presence

of disease and the level of parasitism was measured. During the adult flight period, pheromone traps

(“Panador”) were placed in each plot. They were checked on 27 April, 3 May and 21 May.

A count of larvae was conducted using a “Chemical knock-down” method. At each point on 2001

05 30, a tree was selected and two 0.5 X 1.0 m blankets were placed under it on opposite sides of the

trunk. The trees were sprayed with a ten times greater dose of Arrivo pyrethroid insecticide. A count

of dead larvae was made 10 days after spraying. The trees were cut down so that their crowns fell on

polyethylene sheets so that larvae remaining in the crowns could be counted.

Pheromone Traps and Other Methods in Assessing Pine Beauty Moth

(Panolis flammea Schiff.)

Dr. Algimantas Žiogas

Lithuanian University of Agriculture
Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311 177

Results

Counts of pine beauty moth pupae made early in the spring before emergence of adults has shown

that pupae in the study area were distributed rather unevenly. The general ratio of females and males

in the area was 1.9:2.3. This indicated that the mass outbreak is already in the third stage. The studies

showed no essential differences in the dependence of male and female pupae ratio on the total

number of pupae. However, there is a tendency that when the number of pupae in the litter is greater

than 10/m2

, their ratio is in favor of males.

Studies on flight dynamics of pine beauty moth were determined also in the same places by using

pheromone traps. Males were found mostly in the places where females accumulated after emergence,

or if they were not present there, males responded to a synthetic attractant. For the sake of

convenience, traps can be placed at a height of 3-4 m. For calculating the abundance of males in the

crowns, the coefficient is 7.8.

Determination of the location where the most intensive flying of females occurred could be

ascertained only by secondary methods – according to the place of egg laying, i.e. where larvae were

the most abundant in tree crowns. It appeared that areas of larval abundance did not coincide with

where pupae occurred or where males were caught by pheromone traps.

We observed that the high density of the population seems to have moved to the northwest from the

initial location of pupae; this may be related to the prevailing winds during the flight period of the

moths. The counts of larvae accurately reveal the current state of the population at the place of

infestation but they are hardly suitable for forecasting damage intensity in the following year, or for

planning future protection measures.

Conclusions

1. Methods that are currently applied to evaluate pine beauty moth population densities reveal

accurately the present state of the population, but they are hardly suitable for long-term

forecasting.

2. Counts of pupae in the spring is the most accurate method for forecasting current densities of pine

beauty moth.

3. Pheromone traps, at best, are suitable only to determine the periodicity and intensity of flying

adult males and for convenience, they can be placed at the height of 3-4 m.
178 Proceedings: Ecology, Survey and Management of Forest Insects GTR-NE-311

Pine beauty moth (Panolis flammea Schiff.) is one of the most serious defoliators that periodically

threatens Scotch pine forests on poor sandy soils in Lithuania. Population increase of this pest began

in 1999. Because a maximum of only 15% defoliation was predicted in particular areas, no

additional funding was required for suppressing the population and no apparent damage was realized.

Significant damage was predicted for 2000 and it was estimated that suppression measures would be

needed on an area of only 13,000 ha, however funding was available to treat only 6,450 ha.

Therefore, by the end of that summer, the outbreak expanded to an area of 44,800 ha, 4,000 ha of

which was completely defoliated.

Extensive surveys revealed that in 2001, slight defoliation (30-50%) should be expected on an area of

8,500 ha, medium defoliation (50-75%) on 103,000 ha and heavy defoliation (>75%) on 19,100 ha.

It was estimated that it would cost 3.1 million Lt (Lita; $0.32 U.S. = 1 Lita) to treat 37,900 ha

(forest with >30% defoliation), 2.3 million Lt to treat 29,400 ha (>50% defoliation), and 1.2 million

Lt to treat 19100 ha (forests with >75% defoliation). This resulted in a heated discussion about the

justification for area-wide suppression measures:

• Arguments against suppression: (1) natural enemies will bring to an end the outbreak (59±8% of

overwintering pupae were parasitised, mainly by the tachinid fly Ernestia rudis Fall. and

ichneumonid Rictichneumon pachymerus Ratz.); (2) there is no money available in the current

budget for these expenses.

• Arguments for treatment: (1) forests are at risk because repeated 80-100% defoliation can be fatal

for pines; (2) parasites will not prevent tree damage because they kill P. flammea only during their

final stages of development.

As a result of these deliberations, it was determined that suppression was justified to treat 18,620 ha

of forests (~ 60%); conventional pyrethroids were used. Damage to varying degrees was recorded on

an area of 1,243 ha (8,530 ha new), however the forests most at risk were protected against further

defoliation and dieback.

Based on the forecast for 2002, slight defoliation on 4,485 ha, medium on 4,670 ha, heavy on 5,320

ha, and projected pupal parasitism of 54-61%, suggests that the current outbreak will persist and will

spread to new territories. Aerial sprays, using mainly biological insecticides, were scheduled on an

area of 12,880 ha and 1.2 million Lt funding was allocated. Pine beauty moth pupae overwintered

and emerged successfully but, surprisingly, females laid very few eggs (67% of the eggs have not

maturated). The suggested reason for that could be the lack of adequate food because of the high pest

densities that occurred in the previous year. Consequently, only the most damaged forests were

treated in 2002 (1,900 ha) to prevent any further defoliation, and 0.3 million Lt (25%) was

expended. As a result the outbreak terminated.

Conclusions

•Parasites were not important in terminating pine beauty moth outbreaks.

•Pest management activities (suppression) effectively preserved forests at risk.

•Delaying funding for pest management is more expensive – 1.47 million Lt was spent over three

years instead of about 0.5 million Lt that was needed in the first year of the outbreak.

Furthermore the initial expenditure would have prevented 50,000 ha of damaged forests.

Pine Beauty Moth (Panolis flammea Schiff.) Outbreak Management:

Suppression Versus Natural Enemies

Paulius Zolubas

Lithuanian Forest Research Institute, Girionys, 4312 Kaunas, Lithuania
Printed on Recycled Paper

McManus, Michael L.; Liebhold, Andrew M., eds. 2003. Proceedings: Ecology,

Survey and Management of Forest Insects; 2002 September 1-5; Kraków,

Poland. Gen. Tech . Rep. NE-311. Newtown Square, PA: U.S. Department of

Agriculture, Forest Service, Northeastern Research Station. 178 p.

Contains 46 papers and abstracts presented at a meeting sponsored by the

International Union of Forestry Research Organizations (IUFRO) Working Party

S7.03-06, “Integrated Management of Forest Defoliating Insects,” and Working

Party S7.03.07, “Population Dynamics of Forest Insects.”

Keywords: Forest insect, defoliator, integrated management, population dynamics,

ecology, gypsy moth, bark beetle, budworm, moth

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