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

Abstract

AbstractThe 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.