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Forest Service Research Note

Experiment Station

so-324

June 1986

Studies on the Flight Capabilities of Dendrocfonus frontalis

and IPS calligraphus: Preliminary Findings

Using Tethered Beetles

D. N. Kinn

SUMMARY

Studies provide preliminary results of the flight capabilities of the southern pine beetle and the eastern sixspined engraver.

INTRODUCTION

The current widespread outbreak of the southern pine

beetle, Dendroctonus frontalis Zimmermann, and the

cut-and-leave technique employed to stop individual

spot growth have raised many questions about the flight

capabilities of bark beetles and the effectiveness of this

co@ol method. Few studies have dealt with the flight

capabilities of the southern pine bark beetles. Radioactive tagging and marking beetles with fluorescent powders have been used to study dispersal of the southern

pine beetle (Gara 1967, Moore et al. 1979). Flight mills

have been used to study the flight capabilities of other

bark beetles (Atkins 1961, Kinn 1971).

The studies reported here are preliminary results of

the flight capabilities of the southern pine beetle and the

eastern six-spined engraver. Ips calhgraphus (Germ.).

These findings are intended to provide preliminary

knowledge regarding the flight capacity of southern bark

beetles.

MATERIALS AND METHODS

The flight mill used in this study was a modification of

one designed by Chambers, Sharp, and Ashley (1976).

The mill is suspended rather than being rested on a

platform. This ensures a true vertical orientation (fig. 1).

The mill itself consists of an almost frictionless Teflon@

bearing and a rotor support that rides on a magnetic

cushion. The rotor arm is 16 cm from its axis to its tip and

circumscribes a circle 1 m in length. Six mills are housed

on an enclosed table and each mill provides data to a

recorder that tallies time and distance flown for that particular mill. This information is stored in a memory circuit

after cessation of a beetle’s flight. Counting will not resume if an individual beetle begins a second flight after

a brief resting period. Therefore, the data presented here

is for only the initial, uninterrupted flight. After each flight

the beetles were removed from the rotor and examined

for gender.

Infested loblolly pines (Pinus taeda Linn.) were felled,

cut into bolts and transported to the laboratory where

they were held in emergence boxes. Emerging beetles

were collected at hourly intervals and from these collections beetles were selected at random for testing. Plastic

rubber cement was used to attach the beetles to a pin

attached to the rotor arm. All tests were carried out in a

still atmosphere at 18-26°C 22-28 percent R.H., under

constant illumination of about 500 luxes.

RESULTS AND DISCUSSION

In October 1981, 13 D. frontalis (69 0, 7~3 8) were

collected and flown. The approach of cooler weather and

resulting lack of beetles precluded additional flights.

Thirteen 1 . calligraphus (6s ~3, 78 8) were flown in the

fall of 1981 (Sept.-Dec.) and an additional 8 1 . ca//igraphus (48 CT, 4 9 0 ) were flown in August 1982. No significant differences in duration, distance, or velocity of flight

were noted between female and male southern pine

beetles (table l), nor between female and male sixspined engravers (table 2).

Southern Forest Experiment StationTT-10210 U.S. Postal Services Bldg., 701 Loyola Avenue, New Orleans, La. 70113

Forest Service, U.S. Department of Agriculture.

Sewing Alabama, Arkansas, Louisiana, Mississippi, E. Oklahoma, Tennessee, E. Texas, Puerto Rico, U.S. Virgin islands

1
Figure 1 .-Suspended flight mill and sensing device used to test flight

capabilities of the southern pine beetle and eastern sixspined engraver.

The maximum distance flown by a single southern

pine beetle was 1.6 miles with the average being slightly

over one-half mile. The six-spinned ips, being a more

robust insect, flew farther than the southern pine beetle.

The maximum distance flown by 1 . callisraphus in a single flight was 4 miles with an average flight of slightly

over 1 mile. A similar study revealed that Ips confusus

LeConte can fly non-stop for a distance of 7.8 miles with

the average flight distance being 2.6 miles (Kinn 1971).

The greater flight range of engraver beetles may have

significance for the proliferation of southern pine beetle

infestations. In nonepidemic periods the southern pine

beetle is associated with Ips beetles, with the latter often

attacking first (Hain and McClelland 1979).

Admittedly, tethered flight has many disadvantages

over free flight. The beetles are continually attempting to

correct for a straight line flight (Hocking 1953), and they

only have to supply thrust. Lift requires the expenditure

of more energy than thrust (Hocking 1958) and the former is provided by the mill. Even considering these limitations, the flight capability of tethered southern pine

beetles agrees with limited field observations.

In a study conducted in October and November, radioactively tagged southern pine beetles were found to

travel downwind a distance of 364 meters (1194.3 ft)

(Moore et al 1979) and beetles dusted with a fluorescent

powder in June were found one mile from their emergence site (Gara 1967). In the absence of an attractant

or at distances greater than 20-25 feet from an attractant, the southern pine beetle will tend to disperse (Gara

1967, Gara and Coster 1968). Southern pine beetles,

dusted with a fluorescent powder and released in an

open area in the absence of any attractant, were observed to fly upward at a steep angle of ascent (Kinn,

unpublished observation). In contrast, in an understory,

southern pine beetles tend to fly 4 to 18 feet above the

forest floor (Gara, Vite, and Cramer 1963). It is possible

that beetles flying vertically could be carried considerable distances by upper level winds. This is the conclusion reached by Forsse and Solbreck (1985) in their

studies on the dispersal of Ips typographus L. They estimated that approximately 10 percent of the beetle population flies above the canopy and can be carried distances in excess of 11 miles. It has been reported that

southern pine beetle infestations occur in the direction of

prevailing winds (Coster et al. 1978), at least during the

summer (DeMars and Hain 1980).

It is presumed that cut-and-leave reduces beetle populations by creating higher temperatures under the bark

and through drying of the bole. However, the entire

beetle population is not eliminated using either cut-andleave or cut-and-top (Hodges and Thatcher 1976). Surviving beetles may disperse to other areas (Coster

1977). In view of the limited observations that have been

made, this dispersal distance may be considerable. The

present southern pine beetle outbreak in Louisiana and

east Texas is likely to continue for several more years

and it may move eastward if past patterns are repeated.

Also, it can be assumed that outbreaks will continue to

occur in a sporadic pattern once the present outbreak

subsides. A thorough understanding of the dispersal capability of this species throughout the year and the factors affecting dispersal are essential if we are to predict

or control this pest in the future.

REFERENCES CITED

Atkins, M. D. A study of the flight of the Douglas-fir

beetle, Dendroctonus pseudotsugae Hopk.

(Coleoptera: Scolytidae) Ill. Flight capacity. Canadian

Entomologist. 93: 467-474; 1961.

Chambers, D. L.; Sharp, J. L.; Ashley, T. R. Tethered

D. N. Kinn is research entomologist with the Forest Insects Research project at Alexandria, Louisiana, Southern Forest Experiment Station, Forest

Service-USDA.

2
Table l-Time, distance and velocity of Dendroctonus frontalis flights

No.

Time (min.) Distance (meters) Velocity (mlmin.)

Range Mean SD Range Mean SD Range Mean SD

99 6 6-131 75.7 23.6 133-2566 962.7 363.3 6.1-19.6 13.6 2.4

68 7 14-224 97.3 30.7 224-1930 994.3 265.2 7.2-l 6.0 12.1 1.5

Both 13 6-224 67.3 32.1 133-2566 979.7 207.6 7.2-l 9.6 12.9 1.3

Table 2--Time, distance and ve/ocHy of Ips calligraphus flights

Time (min.) Distance (meters) Velocity (m/min.)

No. Range Mean SD Range Mean SD Range Mean SD

99 10 4-166 50.5 16.9 50-4025 1425.4 497.7 12546.7 29.5 3.6

68 1 1 4-206 63.5 19.6 107-6416 2261.7 615.5 9.044.3 29.4 3.9

Both 2 1 4-206 67.6 13.5 50-6416 1673.9 393.0 9.046.7 29.4 2.6

insect flight: a system for automated data processing

of behavioral events. Behavior Research Methods

and Instrumentation. 8: 352-356; 1976.

Coster, J. E. Towards integrated protection from the

southern pine beetle. Journal of Forestry. 75: 481-

484; 1977.

Coster, J. E.; Hicks, R. Ft., Jr.; Watterston, K. G. Directional spread of southern pine beetle (Coleoptera:

Scolytidae) infestations in east Texas. Journal of the

Georgia Entomological Society. 13: 315-321; 1978.

DeMars, C. J.; Hain, F. P. Bark beetle dispersal related

to patterns of tree mortality and wind. In: Berryman,

A. A.; Safranyik, L., eds. Proceedings of the 2nd

IUFRO conference on dispersal of forest insects: evaluation, theory, and management implications. Pulman, WA: Washington State University; 1980. 66-78.

Forsse, E.; Solbreck, C. Migration in the bark beetle Ips

fvpographus L.: duration, timing and height of flight.

Zeitschrift fuer angewandte Entomologie. 100: 47-57;

1985.

Gara, R. I. Studies on the attack behavior of the southern

pine beetle. I. The spreading and collapse of outbreaks. Contributions from Boyce Thompson Institute.

23: 349-354; 1967.

Gara, R. I.; Coster, J. E. Studies on the attack behavior

of the southern pine beetle. Ill. Sequence of tree infestation within stands. Contributions from Boyce Thompson Institute. 24: 77-85; 1968.

Gara. R. I.; Vite, J. P.; Cramer, H. H. Manipulation of

Dendrocfonus frontalis by use of a population aggregating pheromone. Contributions from Boyce Thompson Institute. 23: 55-66; 1965.

Hain, F. P.; McClelland, W. T. Studies on declining and

low level populations of the southern pine beetle in

North Carolina. In: Hain, F. P., ed. Population dynamics of forest insects at low levels. ESPBRAP work

conference; 1979 August 7-10; Raleigh, NC: North

Carolina State University; 1979.

Hocking, B. The intrinsic range and speed of flight of

insects. Transactions of the Royal Entomological Society of London. 104: 223-345; 1953.

Hocking, B. Insect flight. Scientific American. 199: 92-

96, 98; 1958.

Hodges, J. D.; Thatcher, R. C. Southern pine beetle

survival in trees felled by the cut and top-cut and leave

method. Res. Note. SO-219. New Orelans, LA: US.

Department of Agriculture, Forest Service, Southern

Forest Experiment Station; 1976. 5 p.

Kinn, D. N. The life cycle and behavior and Cercoleipus

coelonotus (Acarina: Mesostigmata). University of

California Publication Entomology. 65. 66; 1971.

Moore, G. E.; Taylor, J. F.; Smith, J. Tracing dispersal of

southern pine beetles from felled brood trees with

Phosphorus 32. Journal of the Georgia Entomological

Society. 14: 83-87; 1979.

aU.S.GOVERNMENTPRINTlNCOFFICE:1986 -659- 080 4003lREGlONNO.4 3