bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of traps used to monitor southern pine beetle aerial populations and sex ratios
Authors: Cronin James T. , Hayes Jane. L. , Turchin Peter
Published: March 2003

1 Various kinds of traps have been employed to monitor and forecast population trends of the southern pine beetle (Dendroctonus frontalis Zimmermann; Coleoptera: Scolytidae), but their accuracy in assessing pine‐beetle abundance and sex ratio in the field has not been evaluated directly.

2 In this study, we used fluorescent powder to mark pine beetles emerging from six isolated infestations. We then compared estimates of total abundances and proportions of males emerging from within each infestation to the estimates from three types of traps: passive sticky traps (2, 5, 10 and 20 m away from the source of beetles), multi‐funnel traps baited with pine beetle attractants (100 m away) and pine trees baited with attractants (also 100 m away).

3 We found that the proportion of males captured in traps was significantly affected by the type of trap used.

4 Within an infestation, equal proportions of males and females were marked (0.53 ± 0.02 males; mean ± SE), but the proportions captured in trap trees and passive traps were more female biased (0.42 ± 0.03 and 0.46 ± 0.01 males, respectively). On the other hand, funnel traps provided an estimate of the proportion of males that was nearly identical to the proportion from within infestations (0.51 ± 0.03).

5 Numbers of marked beetles captured in traps were uncorrelated with the numbers of marked beetles emerging from the focal infestations. This suggests that traps positioned around an infestation may not be effective at estimating relative abundances of beetles within the infestation.
Rapid gall midge adaptation to a resistant willow genotype
Authors: Glynn Carolyn , Larsson Stig
Published: March 2003

Abstract 1 We conducted two experiments to investigate why a basket willow Salix viminalis L. genotype, known to be highly resistant to the leaf‐roller gall midge Dasineura marginemtorquens (Bremi), should support very high gall densities in a field plantation at Tälle, south Sweden.

2 The first experiment was a field test of the hypothesis of fine‐scale host adaptation in the gall midge/willow system. Support for the hypothesis would be established if midges originating from resistant willows and those originating from nearby susceptible willows differed in their abilities to initiate galls and complete development on resistant plants.

3 The objective of the second experiment was to explore whether there was a genetic basis to the trait for virulence in the midge population and to investigate any potential trade‐offs this trait may entail.

4 Our results indicate that there was a fine‐scaled microgeographic genetic structure to the midge population at Tälle. Midges originating from resistant plants had a heritable trait that enabled them to establish galls on resistant plants.

5 Midges able to initiate galls on the resistant genotype had longer developmental time on the susceptible genotype. This suggests that there is a physiological cost associated with being adapted to the resistant willow genotype.

6 We suggest that driving forces behind the observed host adaptation are selection imposed on the midge population by very strong willow resistance and restricted gene flow in the midge populations due to the special life history features of D. marginemtorquens.
Expanding radiation quarantine treatments beyond fruit flies
Authors: Hallman Guy J.
Published: March 2003

1 The potential of ionizing radiation as a disinfestation treatment for insects other than tephritid fruit flies is discussed. Radiation quarantine treatments are unique in that insects are not killed immediately but rendered sterile or incapable of completing development.

2 The most tolerant insect stage to radiation is that which is most developed. Female insects, but not always mites, are sterilized with equal or lower doses than males.

3 Insects irradiated with sterilizing doses usually have shorter longevities than non‐irradiated ones. Low oxygen conditions often increase tolerance to radiation.

4 Insects in diapause are not more tolerant of radiation than non‐diapausing ones.

5 Some pests of several groups, such as aphids, whiteflies, weevils, scarab beetles, and fruit flies, may be controlled with doses ≤ 100 Gy. Some lepidopterous pests and most mites require about 300 Gy. Stored product moths may require as much as 1 kGy to sterilize, and nematodes could need > 4 kGy.

6 Even though application of irradiation to pallet‐loads of produce could mean that up to three times the minimum required dose is applied to the perimeter of the pallet, many fresh commodities tolerate doses required for quarantine security against many quarantined pests. Irradiation is arguably the most widely applicable quarantine treatment from the standpoint of commodity quality.
Deterred oviposition response ofMonochamus alternatus(Coleoptera: Cerambycidae) to oviposition scars occupied by eggs
Authors: Anbutsu Hisashi , Togashi Katsumi
Published: March 2003

1 The oviposition behaviour and response ofMonochamus alternatusfemales to oviposition scars were investigated in the laboratory.

2 Prior to oviposition, females gnawed at the bark surface ofPinus densiflorabolts to make a wound. Then females turned their bodies 180° to position their ovipositors over the wounds and inserted them under the bark through the wounds. After an oviposition, a jelly was deposited while the ovipositor was still inserted. The females then withdrew their ovipositors and rubbed the oviposition scars with the tips of their abdomens.

3 When searching females encountered oviposition scars, they stopped walking and drummed the surface and inside of the oviposition scars with their maxillary and labial palpi.

4 Eighty‐six percent of females left oviposition scars containing single eggs after the palpation. By contrast, when females encountered oviposition scars containing no eggs, 76% of them began to gnaw at the scars and 64% deposited single eggs. The response to artificial oviposition scars was similar to that to vacant oviposition scars made by the females.

5 The results of various observations and experiments showed that the females could recognize oviposition scars and discriminate the scars occupied by single eggs from vacant ones, and suggested that the palpation of oviposition scars was the critical discrimination behaviour, indicating mediation by chemical cues.
Modelling the use of NPV for the biological control of Asian gypsy moth Lymantria dispar invading New Zealand
Authors: Barlow N. D. , Caldwell N. P. , Kean J. M. , Barron M. C.
Published: March 2003

1 The accidental introduction of the Asian strain of gypsy moth (AGM) Lymantria dispar (L.) to New Zealand poses a major threat to New Zealand's forestry industry. To aid eradication and control decisions in the event of its establishment, a model was developed for the effect of nuclear polyhedrosis virus (NPV) as biological control for AGM in New Zealand.

2 The model simulates within‐ and between‐season gypsy moth population dynamics, including temperature‐dependent development, density dependence through predation and resource limitation, and interactions with NPV.

3 Following its introduction to New Zealand, AGM is predicted to increase more quickly and have more severe outbreaks than the European strain. In the absence of predators, the model predicts initial outbreaks then damped oscillations to an equilibrium.

4 In the model, a single application of NPV (2500 GPIB ha−1) at the time of maximum larval density gave up to 80% suppression of peak larval densities in the following year. The same level of suppression was achieved in the absence of predators.

5 In the long term, the model predicted that spraying when an outbreak was just beginning gave best results (a 50–70% reduction of the following two outbreaks). Simulation of threshold spraying resulted in NPV application, on average, every 7 years and suppression of outbreak densities by 40–70%. Following a single application, NPV was maintained in the population as a classical biological control agent, giving approximately a 20% reduction in outbreak densities.

6 Eradication of AGM using NPV was possible if larval densities were very low.
Spider abundance and diversity in apple orchards under three insect pest management programmes in Washington State, U.S.A.
Authors: Miliczky Eugene R. , Calkins Carrol O. , Horton David R.
Published: March 2003

1 Many apple growers in Washington State, U.S.A. use mating disruption (MD) for control of codling moth, Cydia pomonella (Linnaeus). Fewer applications of synthetic, broad‐spectrum insecticides are made in MD orchards than in orchards under conventional (C) management. Spider abundance and diversity in MD, C and certified organic (O) orchards were compared. Spiders inhabiting the trees (arboreal), the understory vegetation, and the ground surface were studied.

2 Total arboreal spider density and total understory spider density were significantly higher in O orchards than in MD and C orchards. Many species occurred in both the trees and the understory.

3 Arboreal, visually orientated, hunting spiders and arboreal ambushers/runners were significantly more abundant in O orchards compared to C and MD orchards. Visual hunters were significantly more abundant in MD compared to C orchards. Numbers of spiders in two other guilds (web‐makers and nocturnal hunters) showed no statistical differences with respect to orchard management type.

4 The highest density of ground surface‐dwelling spiders occurred in one of the O orchards. Two C orchards had higher densities than any MD orchard. Ground surface species were distinct from those in the understory and the trees.

5 With one exception, an orchard's arboreal fauna was most similar to that of another orchard under the same type of pest management. Three exceptions were noted among comparisons of the understory faunas. The ground surface‐dwelling fauna of one O orchard was distinctive, whereas that in the second O orchard was similar to the C and MD orchards.

6 Reduced use of synthetic, broad‐spectrum insecticides in MD orchards did not result in arboreal spider densities comparable to those found in O orchards. A contributing factor may be that all species were univoltine. Spider populations may thus be severely reduced by even a small number of synthetic, broad‐spectrum insecticide applications and the time required for recovery may be lengthy.
Dynamics of twolined chestnut borerAgrilus bilineatusas influenced by defoliation and selection thinning
Authors: Muzika R. M. , Liebhold A. M. , Twery M. J.
Published: March 2003

1 The twolined chestnut borer,Agrilus bilineatus(Coleoptera: Buprestidae), is a major mortality agent of stressed oak trees. However, patterns of abundance and population change are not well understood.

2 We studied the spatial and temporal variation in abundance of twolined chestnut borer adults during a gypsy moth,Lymantria dispar(Lepidoptera: Lymnatriidae), outbreak and examined the influence of both defoliation and thinning on twolined chestnut borer abundance.

3 In stands that were defoliated by gypsy moth, extensive defoliation occurred in one year, and major overstory tree mortality followed in the next. Most mortality occurred in the year preceding the peak year of twolined chestnut borer abundance and abundance of twolined chestnut borer was positively associated with defoliation and mortality in the previous year.

4 Twolined chestnut borers were more frequently associated with poor or fair crown condition trees than trees with good crown condition and were more abundant on members of the red oak group than the white oak group.
Population dynamics of the bird cherry‐oat aphid, Rhopalosiphum padi (L.), during the autumn and winter: a modelling approach
Authors: Morgan Derek
Published: March 2003

1 A simulation model was developed to investigate the inter‐relationship of factors influencing the population dynamics of the bird cherry‐oat aphid (Rhopalosiphum padi (L.)) in barley crops during the autumn and winter.

2 The model incorporated algorithms describing alate immigration, development and survival of adults and nymphs, fecundity and morph determination in newly born nymphs.

3 The model was validated against pest outbreaks in barley fields in south‐east England.

4 It simulated accurately the size of the outbreaks with predictions of peak aphid populations within 20% of the observed in all but one case. Similarly, all but one of the year‐sowing date combination predictions of timing of peak abundance fell within 14 days of the observed.

5 A sensitivity analysis of the model highlighted the relative importance of various population processes in determining simulated aphid population dynamics; decreasing mortality rates of apterous nymphs by as little as 5% over the autumn and winter increased peak densities by as much as 60‐fold, whereas increasing daily temperatures by only 1 °C more than doubled peak aphid abundance.

6 The model identified our understanding of the mechanisms of aphid mortality as a limiting factor in the accurate prediction of R. padi outbreaks in the field.
Evaluation of traps of six different designs to capture pine sawyer beetles (Coleoptera: Cerambycidae)
Authors: De Groot Peter , Nott Reg
Published: March 2003

1 Sawyer beetles (Coleoptera: Cerambycidae) and metallic wood‐boring beetles (Coleoptera: Buprestidae) attack recently killed or felled trees. They are attracted to potential hosts by volatiles and possibly by visual cues. We examined traps of six different designs to determine the role of silhouette and shape in the capture of pine sawyer beetles, Monochamus L.

2 Traps with a round black cylinder, a single vane (clear or black), or cross vanes (clear or black) all mounted above a pan were compared to an open pan. Each pan contained soapy water to retain insects.

3 Traps with a black silhouette were significantly more effective in capturing male and female Monochamus scutellatus (Say) than traps with or without clear vanes. For both sexes of M. mutator LeConte, pan traps were as effective as traps with a black silhouette. Silhouette was not important for the capture of male and female M. notatus (Drury). Trap catches for the six trap types were not significantly different for male Buprestis maculativentris Say.

4 A pan trap with a black silhouette is recommended for general use in capturing wood‐boring cerambycids and buprestids.
Development and functional response of Coelophora inaequalis (Coleoptera: Coccinellidae) feeding on brown citrus aphid, Toxoptera citricida (Homoptera: Aphididae)
Authors: Wang Jin‐Jun , Tsai James H.
Published: March 2003

1 Development and survivorship of Coelophora inaequalis (F.) were evaluated in the laboratory on the brown citrus aphid, Toxoptera citricida (Kirkaldy) at 20 and 25 °C. Coelophora inaequalis could complete its life cycle feeding on T. citricida at these two temperatures. The developmental period from egg to adult was significantly longer at 20 °C (24.7 d) than at 25 °C (15.9 d). The survivorship of combined immature stages were higher at 25 °C (39.2%) than at 20 °C (34.3%).

2 The effects of prey densities (4–64 aphids per leaf disk) on the functional responses of C. inaequalis fourth‐instar larvae and female adults were investigated using grapefruit leaf disks over a 24‐h period at 25 °C and a photoperiod of LD 14 : 10 h. Logistic regression analyses indicated that fourth‐instar larvae and adults exhibited a type II functional response to aphid density. Fourth‐instar larvae had a higher search rate (0.1305) than C. inaequalis female adults (0.0989). The handling time of fourth‐instar larvae (30.4 min) was significantly longer than that of female adults (5.8 min). Collectively, C. inaequalis appears to be a promising biological control agent of T. citricida in the citrus groves.
Predation by the carabid beetles Pterostichus madidus and Nebria brevicollis is affected by size and condition of the prey slug Deroceras reticulatum
Authors: Mair J. , Port G. R.
Published: March 2003

1 Slugs are important pests in many agricultural crops but molluscicides commonly used to control slugs affect non‐target organisms. Encouraging biological control may help to reduce molluscicide use, but the efficiency of potential natural enemies needs to be investigated.

2 Serological tests have shown that certain carabid species consume slugs. These techniques, however, do not distinguish between scavenging and true predation, nor do they provide information on the size or other characteristics of the prey consumed. The study reported here was undertaken to establish whether scavenging of dead slugs might be an important factor contributing to positive serological test results.

3 Both Pterostichus madidus (Fabricius) and Nebria brevicollis (Fabricius) consumed Deroceras reticulatum (Müller) under laboratory conditions. Dead slugs were scavenged in preference to injured or healthy slugs.

4 Only small, live slugs (< 0.11 g) were killed by both beetle species, which may, therefore, be incapable of killing larger slugs.

5 These generalist beetle species appeared unable to overcome the defence mucus produced by slugs. The data suggest that positive serological results from field collected beetles may reflect scavenging rather than predation on live or injured slugs.
Comparative efficacy of five types of trap for woodborers in the Cerambycidae, Buprestidae and Siricidae
Authors: McIntosh R. L. , Katinic P. J. , Allison J. D. , Borden J. H. , Downey D. L.
Published: March 2003

1 Traps of four new designs were tested against the conventionally used multiple‐funnel trap to determine whether trapping of large wood‐boring insects can be improved in western Canada. All four new traps used a large collecting receptacle containing detergent‐laced water, and three presented a prominent visual silhouette above the receptacle.

2 In total, 27 336 large woodborers were captured from 10 June to 30 September in an experiment in the southern interior of British Columbia, and 4737 from 6 June to 27 July in an experiment in northern Alberta. The woodborers captured in the British Columbia experiment were mainly beetles in the families Cerambycidae (79%) and Buprestidae (15%), and woodwasps in the family Siricidae (6%). Most woodborers, e.g. three Monochamus spp. and Xylotrechus longitarsus (the predominant cerambycids), were captured throughout the summer, with peak captures in August.

3 Cross‐vane, pipe and stacked‐bottomless‐flower‐pot traps were generally superior to pan and multiple‐funnel traps for insects in nine taxa, but cross‐vane traps were the most effective overall, trapping 32% of all insects captured.

4 The large number of target insects captured in a relatively small number of traps in the two experiments suggests that employment of an efficacious trap with a large vertical silhouette and a wide, escape‐proof collecting receptacle could make mass trapping of large woodborers in timber processing areas operationally feasible.

5 Because the most effective traps were unstable in the wind, and the detergent‐laced water captured unacceptably high numbers of small mammals, design modifications are necessary. We are currently developing a wind‐firm trap, with a prominent vertical silhouette, a wide collecting surface, and an escape‐proof, but dry collecting receptacle.
The influence of leaf age on the oviposition preference of Chrysophtharta bimaculata (Olivier) and the establishment of neonates
Authors: Howlett B. G. , Clarke A. R. , Madden J. L.
Published: March 2003

1 The degree of discrimination shown by a herbivore when selecting oviposition sites has been suggested as a key factor to understanding herbivore population dynamics. Chrysophtharta bimaculata (Coleoptera: Chrysomelidae) is a primary pest of Tasmanian eucalypt forests and can cause severe defoliation. Previous work suggests that females show discrimination when selecting oviposition sites. Our aim was to test the degree of oviposition discrimination exhibited by C. bimaculata with regards to leaf toughness, a character that is critical to neonate survival.

2 We conducted an experiment examining the leaf toughness critical for neonate survival and found that significant larval mortality occurs above a toughness of 46.9 g. We also determined that the maximum toughness of leaves upon which larvae established in the field was 48.2 g, supporting the laboratory result.

3 Field surveys showed that although the majority of eggs were laid on leaves suitable for larval establishment, many eggs were laid on unsuitable, tougher leaves. However, all eggs were normally placed within 20 cm of suitable leaves and glasshouse trials demonstrated the neonates could move this distance without mortality occurring.

4 We conclude that egg batch distribution and larval performance of C. bimaculata will influence the population dynamics of C. bimaculata in two ways. Firstly, the availability of expanding/newly expanding leaves of eucalypt hosts will determine larval carrying capacity. Secondly, at a more localized level, the deposition of large numbers of egg batches on both suitable and unsuitable leaves followed by successful neonate migration increases the risk of resource depletion and poor larval development.
Attacks on living spruce trees by the bark beetle Ips typographus (Col. Scolytidae) following a storm‐felling: a comparison between stands with and without removal of wind‐felled trees
Authors: Schroeder L. Martin , Lindelöw Åke
Published: March 2003

Abstract 1 To maintain biodiversity in forests more wind‐felled trees must be left where they fall. However, there is concern among forest owners that this may result in higher tree mortality caused by the spruce bark beetle, Ips typographus (L.) (Col.: Scolytidae).

2 In the 5 years following a major storm disturbance the number of standing spruces killed by I. typographus was determined in a total of 53 stands. In five of the stands all wind‐thrown trees were left (unmanaged stands) and in 48 of the stands, which were situated at distances of 1.4–10.0 km from each focal unmanaged stand, the wind‐felled trees were removed directly after the storm (managed stands). In the winter preceding the fifth summer new storm‐fellings occurred in the study area.

3 In the 4‐year period between the first and second storm‐fellings, 50–322 standing trees were killed by I. typographus per unmanaged stand. There was a direct linear relationship between the number of storm‐felled spruces colonized by I. typographus and the number of trees subsequently killed in the unmanaged stands.

4 Tree mortality caused by I. typographus in the unmanaged stands was almost nil in the first year, peaked in the second or third year, and decreased markedly to a low level in the fourth and fifth years.

5 In the 4‐year period between the first and second storm‐fellings twice as many trees were killed per ha in the unmanaged stands than in the managed stands: the average difference being 6.2 killed trees per ha, equivalent to 19% of the number of spruce trees felled by the first storm in the unmanaged stands.

6 Much higher numbers of trees were killed per ha in the stand edges than in the interiors of both the unmanaged and the managed stands.
Effects of food nutritive quality and Bacillus thuringiensis onfeeding behaviour, food utilization and larval growth of spruce budworm Choristoneura fumiferana (Clem.) when exposed as fourth‐ and sixth‐instar larvae
Authors: Bauce Éric , Bidon Yannick , Berthiaume Richard
Published: March 2003

Abstract 1 Feeding behaviours, and lethal and sublethal (growth, development and food utilization) effects of Foray 48B, a commercial formulation of Bacillus thuringiensis (kurstaki), were investigated on fourth‐ and sixth‐instar spruce budworm larvae according to food nutritive quality. Nitrogen and soluble sugar content of artificial diets were modified to obtain three different qualities of food, simulating variations in nutritive quality of host tree.

2 Larval development times were longer for Bt‐treated larvae and pupal weights were reduced for sixth‐instar larvae only. Bt‐induced mortality levels were influenced by food quality. Ingested dose of Bt and feeding inhibition times were strongly affected by the Bt treatment, but food quality affected only fourth‐instar larvae. Except for food digestibility, nutritional indices were negatively affected by the Bt treatment and by the reduction in food quality.

3 Contrary to early treated larvae (fourth instar), larvae treated at the beginning of the sixth instar were not able to compensate for Bt injury and were consequently more affected by the Bt‐treatment both in terms of lethal and sublethal effects.

4 Bt efficacy was not directly related to the ingested dose.

5 Increase in larval vulnerability to Bt was more likely a consequence of a general stress induced by a less suitable food than a direct interaction between Bt and food nitrogen or sugar compounds.

6 The application of Bt on late‐instar larvae could be a successful operational strategy at low population levels when field sprays target the insect instead of foliage protection.
Oviposition and mining byPhytobia betulae(Diptera: Agromyzidae) in genotypes of European white birch (Betula pendula)
Authors: Ylioja Tiina , Hinkkanen Sami , Roininen Heikki , Rousi Matti
Published: March 2003

Abstract1  The colonization success of herbivorous insects depends partly on the ability of females to choose suitable host plants.Phytobia betulaeKangas (Diptera: Agromyzidae), a miner of differentiating xylem, infests birch (Betula pendulaRoth andBetula pubescensEhrh.) trees.

2  In a field experiment we measured successful ovipositions in the long shoots of eight 5‐year‐old‐birch genotypes. Later in the growing season, in the same experiment, we counted the number of larvae from the same birch genotypes (different replicates).

3  We attempted to determine wherePhytobiafemales lay their eggs in the birch canopy, what kind of shootsPhytobiautilize, whether birch genotypes differ in their susceptibility toPhytobia, and which tree characteristics correlate with successful utilization of birch for oviposition and larval development.

4  The ovipositions were concentrated in fast growing shoots and only 5% of the available shoots were utilized. Usually a shoot contained only one oviposition (80% of the cases). However, oviposition pattern resulted in significant aggregations (two to four ovipositions per shoot): 11% of shoots selected for oviposition contained more than onePhytobiaand 22% of larvae shared their shoot with at least one other larva. Although birch shoots were much more abundant thanPhytobia, there may be intraspecific competition for host resources amongPhytobia.

5  Birch genotypes differed in the number of ovipositions but not in the number of larvae, although in general the number of larvae was correlated positively with the number of ovipositions. There were more ovipositions in the faster growing genotypes.
Effects of buckwheat flowers on leafroller (Lepidoptera: Tortricidae) parasitoids in a New Zealand vineyard
Authors: Berndt Lisa A. , Wratten Steve D. , Hassan Paul G.
Published: March 2003

Abstract 1 The provision of floral resources in agricultural ecosystems can potentially enhance biological control of pests by providing nutrients to parasitoids. To test this, the effect of buckwheat Fagopyrum esculentum Moench flowers on leafroller parasitoids was investigated in a New Zealand vineyard.

2 Relative abundance of parasitoids was assessed with yellow sticky traps in buckwheat and control plots. Male Dolichogenidea tasmanica (Cameron) (Hymenoptera: Braconidae) were significantly more abundant in the presence of buckwheat. No significant result was found for female D. tasmanica or either sex of Glyptapanteles demeter (Wilkinson) (Hymenoptera: Braconidae), the other leafroller parasitoid caught.

3 The relative parasitism rate of leafrollers by D. tasmanica was assessed with a leafroller release and recover technique. No difference in parasitism was found between buckwheat and control plots.

4 The sex ratio (% males) of D. tasmanica emerging from recovered leafroller larvae was significantly lower in the presence of buckwheat than in control plots on one of the two release dates. Possible reasons for this increase in female production are discussed.
Variation in insect damage and growth in Eucalyptus globulus
Authors: Floyd R.B. , Farrow R.A. , Matsuki M.
Published: March 2003

Abstract

 Objectives of this study were to examine (i) between‐provenance variation in susceptibility to insects in Eucalyptus globulus and (ii) relationships between insect damage and tree growth. We planted seedlings of 18 provenances of E. globulus from south‐east Australia in a field trial and measured tree growth and insect damage.

 Christmas beetles Anoplognathus spp. were the dominant herbivores during this experiment, and 99% of trees were affected by them. Defoliation of individual trees by Anoplognathus spp. ranged from 0% to 85%.

 The main results of this study were that: (i) provenances of E. globulus from Tasmania and the Bass Strait islands, which had previously shown resistance to autumn gum moth Mnesampela privata and leaf blister sawfly Phylacteophaga froggatti tended to be resistant to Anoplognathus spp.; (ii) mean tree volume was reduced by herbivory; and (iii) the volume‐based performance ranking of provenances changed depending on the probability of insect outbreaks.

 Fast‐growing provenances should be planted in optimal growing areas for E. globulus with low probability of insect outbreaks. However, in suboptimal growing areas, planting slightly slower growing but more resistant provenances is likely to result in greater output than planting fast‐growing provenances when the probability of insect outbreaks is high.
Trap cropping to manage green vegetable bug Nezara viridula (L.) (Heteroptera: Pentatomidae) in sweet corn in New Zealand
Authors: Rea James H. , Wratten Stephen D. , Sedcole Richard , Cameron Peter J. , Davis Stuart I. , Chapman R. Bruce
Published: March 2003

Abstract

The use of trap crops to reduce green vegetable bug (GVB) Nezara viridula (L.) (Heteroptera: Pentatomidae) damage to process sweet corn Zea mays (L.) was investigated in three field experiments.

In the first season, small plots (2.7 m by 10 m) of white mustard Sinapis alba (L.) with pea Pisum sativum (L.) were sown along a crop border and compared with sweet corn alone.

In the second season, black mustard Brassica nigra (L.) was sown at two sowing dates (14 days apart) and compared with a sweet corn control, to examine how the maturity of the trap crop affected numbers of GVB trapped.

A field scale experiment was also conducted to determine the effectiveness of black mustard as a trap crop to protect larger areas of sweet corn from GVB.

In all three experiments, GVB populations were much higher on the trap crops compared with the sweet corn.

In both small plot experiments, GVB were contained largely within the trap crop for 2 weeks until the sweet corn was harvested.

The field scale experiment demonstrated the efficacy of the trap cropping technique to protect larger areas of crop from GVB.

Percentages of damaged sweet corn cobs in the outside row of fields protected by a trap crop were 0% and 1%, respectively, compared with 11% and 22% in control fields.

Trap cropping is recommended as an effective strategy to manage this insect. Options for cultivating or spraying the trap crops to reduce bug survival are discussed.
A molecular identification key for economically important thrips species (Thysanoptera: Thripidae) using direct sequencing and a PCR‐RFLP‐based approach
Authors: Brunner P. C. , Fleming C. , Frey J. E.
Published: March 2003

Abstract

Treatments against pathogens or pests are often very specific and, as a fundamental first step, require the ability to identify taxa correctly and unambiguously. We used PCR amplification techniques to successfully establish a molecular identification key for economically important thrips species.

A PCR amplified 433 bp long fragment of the mitochondrial COI coding gene was analysed by automated direct sequencing and RFLP. Sequencing of 264 individual thrips representing 10 named species detected 17 haplotypes. Variation within species was low, whereas among species variation was high resulting in an average sequence divergence of 18.6% and an average pairwise species differentiation (calculated as FST‐value) of 0.9896.

Two restriction enzymes (AluI, Sau3AI) produced patterns that allowed unambiguous identification of all thrips species.

Statistical support for the quality of the key was given by (i) a highly significant permutation approach, assigning individual haplotypes to the correct species groups and (ii) a hierarchical NJ cluster analysis in which all conspecific individual sequences clustered together with maximal (100%) bootstrap support.

This study has shown that the use of genetic markers represents a valuable alternative for situations, such as epidemiological research, in which correct identification with classical morphological methods is either very difficult and time consuming or virtually impossible.
Use of historical temperature data for timing insecticide applications of the Nantucket pine tip moth (Lepidoptera: Tortricidae): evaluation of damage and volume increment efficacy
Authors: Fettig Christopher J. , Berisford C. Wayne
Published: March 2003

The effectiveness of optimal spray period intervals based on mean daily temperatures were evaluated as a spray‐timing tool to control high density populations of the Nantucket pine tip mothRhyacionia frustrana(Comstock).

 Initial tree growth realized from first generationR.frustranacontrol was compared to that from conventional applications of one insecticide treatment scheduled for each of three annual generations.

 The optimal spray period intervals provided byFettiget al. (2000a)were highly effective for controllingR.frustranainfestations. The control group averaged 47.0 ± 2.2% whole tree damage for all sites and generations as compared to 0.6 ± 0.2% for the treated group.

 Volume gains attributable toR.frustranacontrol averaged 16.9%, 46.4% and 98.6% for first generation control, and 46.6%, 72.7% and 146.3% for conventional applications of one insecticide treatment scheduled for each of three annualR.frustranagenerations at Northampton, Halifax I and Halifax II, respectively. Growth returns increased as mean damage estimates increased for both treatments, suggesting that returns realized from a single, first generation application are likely to increase with population density.
Morphological and genetic identification of the three pine pests of the genus Tomicus (Coleoptera, Scolytidae) in Europe
Authors: Kohlmayr Bernhard , Riegler Markus , Wegensteiner Rudolf , Stauffer Christian
Published: March 2003

Abstract

Morphological characters were elaborated and part of the mitochondrial COI gene was sequenced in order to facilitate the determination of the three European pine bark beetles Tomicus piniperda, T. destruens and T. minor. The sequence information also provided the first information on the phylogenetic and phylogeographical relationships of these species.

Three hair rows were found on the antennal club of T. destruens between the second and third suture. Tomicus piniperda had only one row. Three different hair types were detected on the elytra – two hair types were found on T. piniperda, whereas the third hair type was only detected on the elytra of T. destruens.

The COI region (445 bp) revealed high sequence divergence among T. destruens, T. piniperda and T. minor. The three species proved to be monophyletic species with 16.98–19.23% sequence divergence. A phylogenetic approach placed T. minor and T. destruens as sister taxa, which contradicts the morphological findings.

European populations of T. piniperda shared two haplotypes, indicating a homogenous distribution of the genotypes. In the American populations only one of these European haplotypes was found. The Greek, Italian and Spanish T. destruens populations revealed three population‐specific haplotypes, indicating restricted gene flow.

Species‐specific primers were designed to allow a rapid and definitive determination of the two sibling Tomicus species by PCR.
The impact of host plant species on the larval development of the large pine weevil Hylobius abietis L.
Authors: Thorpe K. V. , Day K. R.
Published: March 2003

The developmental performance of the large pine weevil Hylobius abietis was studied in the laboratory on four species of conifer, Corsican pine Pinus nigra var. maritima, Sitka spruce Picea sitchensis, Douglas‐fir Pseudotsuga menziesii and Japanese larch Larix kaempferi.

 All species supported development, but, there was considerable variation in larval mortality, development time and weight of adults on emergence between host species.

 Levels of mortality were highest in Japanese larch (77%) and lowest in Corsican pine (8.2%), and the heaviest adults emerged from Corsican pine (130 mg) and the smallest from Douglas‐fir (74 mg).

 A constitutive plant defence chemical, lignin, found to vary within a northern provenance of Sitka spruce, also strongly affected larval development.

 The significance of these findings is discussed in relation to the management of H. abietis.
Cottonwood leaf beetle (Coleoptera: Chrysomelidae) defoliation impact on Populus growth and above‐ground volume in a short‐rotation woody crop plantation
Authors: Coyle David R. , McMillin Joel D. , Hall Richard B. , Hart Elwood R.
Published: March 2003

Abstract

The impact of cottonwood leaf beetle Chrysomela scripta F. defoliation on four plantation‐grown Populus clones was examined over three growing seasons. We used a split‐plot design with two treatments: protected (by insecticides) and an unprotected control. Tree height and diameter at 1 m were measured annually and above‐ground volume was calculated.

Protected trees of most clones had grown over 2 m taller after three growing seasons. Diameter differences ranged from over 1–4 cm larger on protected trees. Insecticide protection increased above‐ground volume over 20 dm3 in one clone, and at least 4 dm3 in all others. Chrysomela scripta defoliation resulted in a 50–73% loss of above‐ground volume. Defoliation also resulted in increased lateral branching and forked terminals on unprotected trees.

Defoliation impact varied among clone. The pure Populus deltoides clone 91 × 04‐03 showed the greatest growth response to chemical protection, whereas clone NM2 (P. nigra × P. maximowiczii) responded the least.

Pest control is a key issue in short‐rotation plantation management. Until adequate pest‐resistant clones can be developed and natural enemy complexes better understood, chemical (biorational and organic) and cultural control may be used to reduce impacts of herbivorous pests.
Oviposition preference and neonate performance of Mnesampela privata in relation to heterophylly in Eucalyptus dunnii and E. globulus
Authors: Steinbauer Martin J.
Published: March 2003

Abstract

 The autumn gum moth, Mnesampela privata, is an endemic Australian geometrid that utilizes a number of species within the genus Eucalyptus as hosts. Based on field observations, the moth is thought to be leaf‐type specific for juvenile as opposed to adult eucalypt foliage.

 Laboratory binary choice assays of the oviposition preference of host novice M. privata confirmed that eggs were more likely to be laid upon juvenile rather than adult foliage of Eucalyptus dunnii and two subspecies of E. globulus. This oviposition preference was not influenced by differences in leaf size or adherence to leaves by ovipositing moths. The high specific leaf weights common to adult leaves were associated with reduced oviposition.

 Although neonates fed on both juvenile and adult leaves of most of the trees studied, performance was greater on juvenile as opposed to adult foliage. Juvenile leaves typically had lower specific leaf weights and were nutritionally superior to their adult counterparts. Specific leaf weights above 0.236 mg/mm2 (associated with low water, i.e. = 56.5%, and nitrogen, i.e. = 1.23%, contents) were associated with reduced larval performance. Younger adult leaves, those with lower specific leaf weights, allowed slightly greater larval consumption.

 When ovipositing, this eucalypt‐specific moth discriminates between leaf types of its heterophyllous hosts in favour of types with the lowest specific leaf weight. Less tough leaf types, which are also higher in nitrogen, enable neonates to attain larger body weights.
Response of quaking aspen genotypes to enriched CO2: foliar chemistry and tussock moth performance
Authors: Lindroth Richard L. , Wood Sarah A. , Kopper Brian J.
Published: March 2003

Abstract

Genetic variation in the phytochemical responses of plants to CO2 enrichment is likely to alter trophic dynamics, and to shift intraspecific selection pressures on plant populations. We evaluated the independent and interactive effects of atmospheric CO2 and quaking aspen (Populus tremuloides Michx.) genotype on chemical composition of foliage and performance of the whitemarked tussock moth (Orgyia leucostigma J. E. Sm.).

This research was conducted at the Aspen FACE (Free Air CO2 Enrichment) site in northern Wisconsin, U.S.A. Leaf samples were collected periodically from each of three genetically variable aspen genotypes growing under ambient and elevated CO2, and analysed for levels of primary and secondary metabolites. Tussock moth larvae were reared in situ on experimental trees, and development times and pupal masses were recorded.

Foliar chemical composition varied among aspen genotypes and in response to CO2 enrichment. However, chemical responses of trees to elevated CO2 were generally consistent across genotypes.

Larval development times varied among host genotypes and increased slightly for insects on high‐CO2 plants. Enriched CO2 tended to reduce insect pupal masses, particularly for females on one of the three aspen genotypes.

CO2 × genotype interactions observed for plant chemistry and insect performance in this study with a small number of genotypes are probably too few, and too weak, to shift selection pressures in aspen populations. These results differ, however, from earlier work in which more substantial CO2 × genotype interactions were observed for plant chemistry.
Responses of trembling aspen (Populus tremuloides) phytochemistry and aspen blotch leafminer (Phyllonorycter tremuloidiella) performance to elevated levels of atmospheric CO2 and O3
Authors: Kopper Brian J. , Lindroth Richard L.
Published: March 2003

1 This research was conducted at the Aspen FACE (Free Air CO2 Enrichment) site located in northern Wisconsin, U.S.A. where trembling aspen (Populus tremuloides Michaux) trees were exposed to one of four atmospheric treatments: elevated carbon dioxide (CO2; 560 µL/L), elevated ozone (O3; ambient × 1.5), elevated CO2 and O3, or ambient air. We evaluated the effects of these fumigants on aspen foliar quality and the performance of aspen blotch leafminer (Phyllonorycter tremuloidiella Braun).

2 CO2 and O3 each affected foliar quality, with the major changes consisting of an 11% reduction in nitrogen under elevated CO2 and a 20% reduction in tremulacin under elevated O3. In the CO2 + O3 treatment, nitrogen levels were reduced by 15% and CO2 ameliorated the O3‐mediated reduction in tremulacin levels.

3 Phyllonorycter tremuloidiella were allowed to colonize trees naturally. Elevated CO2 and O3 reduced colonization rates by 42 and 49% relative to ambient CO2 and O3, respectively. The only effect of fumigation treatments on larval performance occurred under elevated O3, where male development time and larval consumption increased by 8 and 28%, respectively, over insects reared under ambient O3.

4 These data demonstrate that the individual and combined effects of CO2 and O3 can alter aspen foliar chemistry and that these alterations in foliar chemistry produce little to no change in larval performance. However, both CO2 and O3 greatly reduced oviposition. In order to ascertain the full effects of CO2 and O3 on insect performance, future studies should address both population‐ and individual‐level characteristics.
Effects of two types of semiochemical on population development of the bird cherry oat aphid Rhopalosiphum padi in a barley crop
Authors: Ninkovic V. , Ahmed E. , Glinwood R. , Pettersson J.
Published: March 2003

1 Field experiments were performed in barley using volatile semiochemicals affecting population density (density‐related substances – DRS) and spring migration (methyl salicylate) in bird cherry oat aphid Rhopalosiphum padi (L.). Natural infestations of aphids were used, and semiochemical dosages were chosen to be biologically relevant based on previous studies. A simple formulation method for active substances using wax pellets was developed.

2 The effect of treatments on aphid populations was analysed in terms of initial colonization of the crop, temporal dynamics of the population and maximum aphid incidence.

3 Treatments caused a significant delay in aphid establishment in the crop, and reduced the average infestation by 25–50% compared with the untreated control. At a moderate attack rate, the treatments with methyl salicylate and DRS gave a significant reduction in maximum aphid numbers.

4 The significant control effect of the treatment encourages further investigation both to increase understanding of the ecological role of the active substances, and to establish the limitations for their use in plant protection.
Predicting time to peak occurrence of insect life‐stages usingregression models calibrated from stage‐frequency data and ancillary stage‐mortality data
Authors: Candy Steven G.
Published: March 2003

1 Integrated Pest Management programmes often require predictions of peak occurrence of particular insect life‐stages to optimize the timing of population monitoring and control operations.

2 Given a known or estimated starting time for a synchronously developing pest population, predictive models estimated from stage‐frequency data alone can only predict the times of peak occurrence assuming a constant mortality rate across stages.

3 Here, continuation ratio regression models of relative stage frequencies estimated from stage‐frequency data are combined with a stage‐specific model of mortality estimated from ancillary mortality data to allow prediction of time of peak occurrence.

4 To calculate time of peak occurrence new mathematical derivations are given for continuation ratio models.

5 The models are used to predict the time of peak occurrence in degree‐day units for each of the first to third larval instars of the Tasmanian Eucalyptus leaf beetle Chrysophtharta bimaculata (Olivier) (Coleoptera: Chrysomelidae), a serious defoliator of Eucalyptus regnans and E. nitens plantations in Tasmania.