Eastern Tent Caterpillar Malacosoma Americanum Research Articles

Colonies of the Eastern Tent Caterpillar Malacosoma americanum (Lepidoptera:Lasiocampidae) Abandon Trails to Depleted Feeding Sites and Follow the Most Direct and Shortest Pathways Between their Tent and Food-Finds

Colonies of the Eastern Tent Caterpillar Malacosoma americanum (Lepidoptera:Lasiocampidae) Abandon Trails to Depleted Feeding Sites and Follow the Most Direct and Shortest Pathways Between their Tent and Food-Finds

Pheromone Trap for the Eastern Tent Caterpillar Moth

The discovery that the eastern tent caterpillar Malacosoma americanum (F.) causes mare reproductive loss syndrome (MRLS), and thus has the potential to continue to result in major economic losses to the equine industry of Kentucky, has resulted in an intensive effort to identify practical means to monitor and control this defoliator, including these experiments to optimize a sex pheromone trap for this pest. A pheromone-baited delta trap with a large opening, such as InterceptST Delta, was more effective than other tested traps. Orange delta traps caught more moths than other tested colors. ETC males are caught at all tested heights within the tree canopy. For monitoring flights, setting traps at 1.5 m would allow easy counting of moths. A 9:1 blend of (E,Z)-5,7-dodecadienal (ETC-Ald) and (E,Z)-5,7-dodecadienol (ETC-OH) was most effective in capturing males. Increasing loading doses of a 3:1 blend (Ald:OH) resulted in the capture of increasing numbers of moths, but a 9:1 blend was more effective than 3:1 blend even at a nine-fold lower loading rate. Pheromone-impregnated white septa caught more moths than gray septa at the same loading dose. The advantages and limitations of using pheromone traps for monitoring M. americanum are discussed.

Managing Eastern tent caterpillars Malacosoma americanum (F) on horse farms to reduce risk of mare reproductive loss syndrome

An equine disease now known as mare reproductive loss syndrome (MRLS) struck the Ohio Valley in 2001-2002 causing thousands of foal abortions and enormous economic loss. Evidence that pregnant mares' exposure to Eastern tent caterpillars Malacosoma americanum (F) induces MRLS created an urgent call for control measures suitable for use on horse farms. We surveyed egg mass distribution and monitored emergence in wild cherry trees, and evaluated reduced-risk treatment strategies including foliage sprays, trunk injections, winter egg mass treatments and barrier sprays to intercept larvae entering pastures. Egg masses were concentrated in the lower canopy, on exposed sides of trees. Larval emergence began in mid-March. Emergence was prolonged (3-4 weeks) in 2002, a typically cool spring, but more synchronized in warmer 2003. Winter treatment of egg masses with bifenthrin or permethrin in a penetrating solvent prevented emergence, but 3% horticultural oil was ineffective for that purpose. Insecticidal soap or oil sprayed directly on neonates gave relatively poor control. Bifenthrin and spinosad were effective as foliage sprays against all instars, their field-weathered residues active for at least 7 days. Bacillus thuringiensis Berliner var kurstaki controlled neonates within 3 days but was less active against late instars, with shorter residual action than bifenthrin or spinosad. Larvae did not avoid insecticide-treated leaves. Trunk microinjection of cherry trees with dicrotophos was effective against all instars, whereas microinjection with milbemectin or abamectin gave poor or inconsistent control. Trunk injection with emamectin benzoate also was effective. Dry permethrin residues controlled late instars crawling in pasture grass for at least 7 days. Factors complicating M americanum management on horse farms are discussed.

Plasticity in foraging patterns of larval colonies of the small Eggar moth, Eriogaster lanestris (Lepidoptera: Lasiocampidae).

Activity patterns of colonies of the central-place foraging (CPF) social caterpillar, Eriogaster lanestris, were electronically long-term recorded under field conditions. Caterpillars showed distinct, highly synchronized activity bouts during which they left their tent, fed on their host-plant and returned to their tent. Caterpillars stayed almost inactive during their digestion phases when they rested inside or on the tent. The number of daily foraging bouts varied over a wide range. On warm and sunny days with high solar irradiation caterpillars left their tent up to 9times, whereas there was only one foraging bout on cool and rainy days. On average, 4.8daily foraging bouts were performed by fourth (pre-final) instar larvae, which is higher than the number reported for another well-known CPF species, the eastern tent caterpillar Malacosoma americanum. Overall, E. lanestris colonies required 31±2 foraging periods to pass their fourth instar within 7.3±1.2days under the temperature conditions prevailing over the course of our experiment. The length of individual foraging bouts as well as the phase of digestion proved to be strongly temperature dependent. In contrast to patterns reported for M. americanum, foraging activities were not bound to specific times of day and also continued during night time if temperature permitted. Changes in light phases only had a modulatory effect on the onset of the next foraging bout. E. lanestris is the first lepidopteran species with CPF social caterpillars reported to show a plastic, but nevertheless strictly synchronized foraging pattern. Caterpillars are thus able to optimize their food intake and enhance growth during periods of thermally favourable conditions while minimizing their exposure to natural enemies.

HIERARCHICAL GENETIC STRUCTURE AND GENE FLOW IN MACROGEOGRAPHIC POPULATIONS OF THE EASTERN TENT CATERPILLAR (MALACOSOMA AMERICANUM).

Genetic structure and inferred rates of gene flow in macrogeographic populations of the eastern tent caterpillar Malacosoma americanum were analyzed at two hierarchical scales: local demes and regional subpopulations. Wright's F-statistics were used to estimate population genetic structure using multilocus genotypic data generated electrophoretically. Estimated values of FST and the distribution of private alleles were then used to obtain indirect estimates of gene flow. We found modest, though significant, genetic structure at both spatial scales, a pattern consistent with high rates of gene flow over the large distances involved. Modest values obtained for Nei's genetic distance also suggested high levels of gene flow across the range of this species, although some gene-flow restriction resulting from isolation by distance was suggested by a positive regression of genetic distance on geographic distance. The observed homogeneity at enzyme loci across the range of M. americanum parallels the reported uniformity in morphology, suggesting a general absence of local genetic differentiation in this widely distributed species. The genetic homogeneity observed in this wide-ranging insect is discussed in terms of organism-specific environmental experience at different spatial scales. Some organisms occupying apparently heterogeneous environments may ameliorate unsuitable local conditions through microhabitat selection or behavioral modification of their microenvironment. This may be accomplished in M. americanum through group shelter construction and behavioral thermoregulation, closely tying thermoregulation to social biology in this species. If in this way the tent helps produce an effectively homogeneous environment for this species across its extensive range, this system may provide a unique example of how social behavior can influence the distribution of genetic variation in a population.

Trail following and recruitment: Response of eastern tent caterpillarMalacosoma americanum to 5?-cholestane-3,24-dione and 5?-cholestan-3-one

Studies were conducted to determine the relative effectiveness of 5β-cholestane-3,24-dione (diketone) and 5β-cholestan-3-one (monoketone) in eliciting trail following from eastern tent caterpillars,Malacosoma americanum. In Y maze tests, trails prepared from the monoketone were followed preferentially over diketone trails, even when the diketone trail was several orders of magnitude stronger. Under field conditions, colonies readily abandoned well-developed trail systems in favor of artificial trails that were established with the monoketone. Other tests in which the caterpillars selected trails prepared from the monoketone (but not the diketone) more often than their own recruitment trails indicate that the monoketone constitutes the chemical basis of recruitment communication in this insect. The study also shows that tent caterpillars are highly sensitive to small differences in the amount of monoketone in a trail and can distinguish between new and aged trails prepared from the compound.

Daily foraging schedule of field colonies of the eastern tent caterpillar Malacosoma americanum.

The daily foraging patterns of seven colonies of the eastern tent caterpillar, Malacosoma americanum, were monitored photoelectronically during the last three larval stadia to provide the first detailed record of the foraging behavior of a gregarious caterpillar under field conditions. Colonies were active an average of 49.3% of each day. Three bouts of foraging, centered about 0600 h, 1500 h and 2000 h (EST), occurred daily during the fourth and fifth stadia. Although ambient temperatures were less favorable for foraging and food processing than at other times of the day, the caterpillars were most active at dusk and dawn, and spent comparatively little time away from the tent during the daylight hours. In the last (sixth) stadium, the caterpillars foraged only under the cover of darkness. A lack of relationship between the rate at which the caterpillars processed food and the spacing of their feeding bouts, indicates that this species follows a schedule of feeding and growth shaped by factors other than those directly related to feeding efficiency and ambient temperature. Colony foraging patterns may reduce caterpillar mortality by minimizing contact between larvae and day-active predators and parasitiods.

Control of Eastern Tent Caterpillar on Black Cherry, 1987

Abstract Eleven insecticides were sprayed on nests of eastern tent caterpillar Malacosoma americanum (F.), found in black cherry, Prunus serotina. Selected trees were growing along roadsides near Auburn, in Lee County, Ala. Tes materials were applied 14 Apr to active colonies and surrounding foliage. Insecticides were applied to runoff using hand-pumped, compressed-air sprayers Chevron Spray Sticker™ was added to all spray mixtures at the rate of 0.5 pt/100 gal. Treatments were replicated 3 times, with each colony constituting. a replication. Efficacy of test materials was determined 7 days posttreatment by removing the colonies from trees, dismantling the webbing, and counting tit number of dead and living larvae.

Niche Relations of Predatory Stinkbugs (Podisus spp., Pentatomidae) Attacking Tent Caterpillars (Malacosoma americanum, Lasiocampidae)

Colonies of the eastern tent caterpillar (Malacosoma americantnm, Lasiocampidae) and nearly 700 associated adults of the predatory stinkbugs Podisus maculiventris, P. placidus, P. modestus and P. serieventris (Hemiptera: Pentatomidae) were censused in 1977-1979 near Ithaca, New York. Most observations were made in an old field where three of the four pentatomid species (all but P. serieventris) occurred and attacked the tent caterpillars. While differences in seasonal timing occurred among the three stinkbug species in the old field, they were found together at tents each sprihg midway through the larval development of M. americanum. During this period of seasonal overlap, the three species displayed similar patterns of activity and sought out prey of similar size on the same trees. The three predators differed, however, in their locations on individual trees: P. placidus occurred most often inside tents, P. maculiventris on or within 30 cm of tents, and P. modestus more than 30 cm distant from the nearest tent. Because individual predators readily attack prey already subdued by other individuals, this divergence in hunting sites reduced interspecific interference in consumption of prey. INTRODUCTION In eastern North America, four predatory stinkbugs of the genus Podisus (Hemiptera: Pentatomidae) prey upon colonial larvae of Lepidoptera and Hymenoptera (sawflies) which defoliate trees and shrubs. Various combinations of the four species have been reported attacking different species of prey (e.g., Kirkland, 1898; Sullivan and Green, 1950; Coppel and Jones, 1962; Tostowaryk, 1971; Morris, 1972). The shifting composition of this association of predators from place to place and time to time suggests that the association is an unstructured assemblage of species, each with its own independent habits. Among the sites frequented each spring by adults of these predators are tents of the eastern tent caterpillar Malacosoma americanum (Fabricius) (Lasiocampidae). I undertook the following study of stinkbugs attacking tent caterpillars to examine whether this association of predators is indeed as unstructured as casual observation suggests. I address two central questions: (1) do the predators differ in their use of a common prey? and (2) do such differences result from independent adaptation to exploit the prey, or from competitive interactions among predators? STUDY SITES AND METHODS Obserations were made during the springs of 1977-79 at three sites near Ithaca, N.Y. Most observations were made in an old field in an advanced state of secondary succession at Whipple Farm Research Area of Cornell University. Tent caterpillars heavily infested black cherries (Prunus serotina Ehrh.) and apples (Malus sylvestris Mill.), and individual trees often bore several tents. Additional observations were made in a mixed forest stand dominated by hemlock (Tsuga canadensis (L.) Carr.), and in a deciduous woods dominated by oaks (Quercus spp.) and hickories (Carya spp.). Tent caterpillars inhabited black cherries in these two sites. Trees infested with tent caterpillars weLe visited and searched for stinkbugs every few days in the old field in 1977-1979 and in the wooded sites in 1977. These wooded 1 Present address: Division of Biology, Kansas State University, Manhattan 66506.

Site of secretion of the trail marker of the eastern tent caterpillar

A new site of secretion of a chemical trail marker was found on the sternum at the tip of the last abdominal segment of the larva of the eastern tent caterpillarMalacosoma americanum. Larvae marked from this site by drawing their sterna along the substrate when they extended existing trails in search of food and again when they established recruitment trails to food-finds. Differences in the quantity or quality of the marker deposited by exploring and recruiting caterpillars may account for the greater activity of the recruitment trails.

A chemical trail factor from the silk of the eastern tent caterpillarMalacosoma americanum (Lepidoptera: Lasiocampidae)

The leaf-feeding larvae of the eastern tent caterpillarMalacosoma americanum (Fabricius) follow silk trails laid down on branches leading from their communal tent to distant foraging sites. The response of colonies reared in the laboratory under seminatural conditions to silk trails washed in methylene chloride and to chemical trails prepared from a solvent extract of their tent or trail silk, showed that one or more soluble components of their trail is essential to the elicitation of the following response. The demonstrated ability of the caterpillars to distinguish between old and newly reinforced silk trails most likely occurs in response to a temporal change in the detectable chemical properties of their trail.