Use of pheromone mimic to cause the disintegration and collapse of colonies of tent caterpillars (Malacosoma spp.)

Abstract

The disruption of the trail‐based communication system of eastern tent caterpillars (ETC) (Malacosoma americanum) and forest tent caterpillars (FTC) (M. disstria) by spraying host trees with a trail pheromone mimic caused the disintegration and collapse of young colonies. A 1‐ppm formulation of 5β‐cholestan‐3‐one or a control formulation was sprayed on trees either before or after eclosion of the caterpillars in the spring. For pre‐eclosion trials, an average of 92% of the FTC colonies on control trees, but only 17% of colonies on treated trees consisted of viable, cohesive aggregates when survival was assessed 5–23 days post‐spray. The remaining colonies had either completely disappeared or were reduced to small, disintegrated fragments. For the ETC, 100% of colonies on control trees and an average of 12% of colonies on treated trees consisted of cohesive aggregates inhabiting tents when survival was assessed 3–41 days post‐spray. The remaining colonies were completely destroyed, reduced to scattered individuals, or to small, disintegrated, shelter‐less fragments. For post‐eclosion trials with the FTC in which colonies were sprayed during their first or second larval stadium, an average of 63% of individuals in control groups but only 7% in treatment groups were still on the sprayed trees 5–18 days post‐spray. For the ETC, colonies were largely unaffected when trees were not sprayed until after the caterpillars had eclosed and established tents. For all trials, the loss of individuals on treated trees was largely attributable to the inability of dispersed and isolated first or second instar caterpillars to maintain secure purchase, causing them to fall from trees and perish. To our knowledge, this is the first study to investigate the potential of manipulating populations of pest species by interfering with a trail‐based, chemical communication system.

Larval Pheromone Disrupts Pre-Excavation Aggregation of Cactoblastis cactorum (Lepidoptera: Pyralidae) Neonates Precipitating Colony Collapse

“…In contrast to studies with ants, the results reported here for C. cactorum, and a previous study of tent caterpillars (Fitzgerald 2008), indicate that trail marking caterpillars are more vulnerable to colony collapse when their trail systems are disrupted. For the 4 experiments reported here, the average survivorship of C. cactorum larvae from colonies on cladodes sprayed with mandibular gland pheromone was approximately 15% compared with 80% on unsprayed control plants.…”

“…As with C. cactorum, new eclosed caterpillars of both tent caterpillar species dispersed independently instead of aggregating en masse on their egg mass, their normal behavior. Although specific causes of C. cactorum larval loss in our study were not determined, tent caterpillar larvae typically perished by losing purchase on the branches of the host tree and falling to the ground (Fitzgerald 2008). A previously reported laboratory study suggested that falls from the plant also may constitute a major mortality factor for C. cactorum (Fitzgerald et al 2016).…”

“…Similarly, losses of colonies of the tent caterpillars, Malacosoma disstria Hübner and Malacosoma americanum (F.) (Lepidoptera: Lasiocampidae), on trees sprayed with a 1 ppm formulation of the trail pheromone mimic 5β-cholestan-3-one, resulted in the loss of 83% of the former colonies and 87% of the latter colonies (Fitzgerald 2008). As with C. cactorum, new eclosed caterpillars of both tent caterpillar species dispersed independently instead of aggregating en masse on their egg mass, their normal behavior.…”

The Ancient Chemistry of Avoiding Risks of Predation and Disease

“…Tent caterpillars travelled in parades around the arena floor. Applications of synthetic trail pheromone disrupts social cohesion of young caterpillars, but was not repellent (Fitzgerald 2009). Thus, repellency of our test materials appears to override such signals.…”

The potential for monitoring and control of insect pests in Southern Hemisphere forestry plantations using semiochemicals

“…Aggregation pheromones, for example, play an important role in sustaining insect attack and infestation levels (Hughes 1974;Silverstein 1981;Wood 1982;Vité and Baader 1990;Schlyter et al 2001), especially of bark beetles. Sex pheromones have also been widely used for mass trapping and mating disruption to suppress various pests, especially relevant to the Lepidoptera (Fitzgerald 2008;Norin 2001;Thorpe et al 1999;Silverstein 1981). Research on plant-derived semiochemicals such as volatile organic compounds can aid in plant protection but are often less specific and can be complex to dissect and apply.…”