Ecological applications of pheromone trapping ofMalacosoma disstriaandChoristoneura conflictana

Abstract

AbstractThe forest tent caterpillar,Malacosoma disstriaHübner (Lepidoptera: Lasiocampidae), and large aspen tortrix,Choristoneura conflictana(Walker) (Lepidoptera: Tortricidae), are important pests of trembling aspen,Populus tremuloidesMichx. (Salicaceae), in western Canada. Populations of both species can be monitored with sex pheromone-baited traps as part of an integrated pest management program. Moths captured in pheromone traps can also be used for ecological studies. Captured males of each species were examined to test the effect of population density, geographic region, and collection date on moth quality. Moth quality was assessed on the basis of wing area and level of infection with microsporidian parasites. The level of microsporidian infection ofM. disstriawas strongly dependent on geographic region but not on population density. MaleM. disstriafrom high-density populations had smaller wings than males from endemic populations. Wing area of maleM. disstriadecreased throughout the flight period. Neither collection date nor microsporidian infection level affected wing area of maleC. conflictana.Collection date also did not affect the level of microsporidian infection ofC. conflictana. These data support pheromone trapping as a tool to detect microsporidian infections and examine their temporal and density-dependent effects on wing size inM. disstriaandC. conflictanapopulations.