Ecological applications of pheromone trapping of Malacosoma disstria and Choristoneura conflictana

The forest tent caterpillar, Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae), and large aspen tortrix, Choristoneura conflictana (Walker) (Lepidoptera: Tortricidae), are important pests of trembling aspen, Populus tremuloides Michx. (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 of M. disstria was strongly dependent on geographic region but not on population density. Male M. disstria from high-density populations had smaller wings than males from endemic populations. Wing area of male M. disstria decreased throughout the flight period. Neither collection date nor microsporidian infection level affected wing area of male C. conflictana. Collection date also did not affect the level of microsporidian infection of C. conflictana. These data support pheromone trapping as a tool to detect microsporidian infections and examine their temporal and density-dependent effects on wing size in M. disstria and C. conflictana populations.

Potential for combining sex pheromones for the forest tent caterpillar (Lepidoptera: Lasiocampidae) and the large aspen tortrix (Lepidoptera: Tortricidae) within monitoring traps targeting both species

Trembling aspen, Populus tremuloides Michx. (Salicaceae), is the most widely distributed tree species in North America (Perala 1990) and is considered to be an ecologically (Hogg et al. 2002) and economically important (Brandt et al. 2003) component of the boreal forest. Due to the recently increased economic value of trembling aspen (Brandt et al. 2003), the impact of native insect defoliators on tree growth and mortality has become commercially important. Two of the most significant defoliators of trembling aspen throughout its range in Canada are the forest tent caterpillar (FTC), Malacosoma disstria Hübner (Lepidoptera: Lasiocampidae), and the large aspen tortrix (LAT), Choristoneura conflictana Walker (Lepidoptera: Tortricidae).

Choristoneura conflictana. [Distribution map].

A new distribution map is provided for Choristoneura conflictana (Walker) Lepidoptera: Tortricidae Attacks mainly Populus tremuloides, also other Populus spp. and broad-leaved trees. Information is given on the geographical distribution in NORTH AMERICA, Canada, Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland, Ontario, Quebec, Saskatchewan, Yukon, USA, Alaska, Arizona, Arkansas, California, Colorado, Iowa, Kansas, Maine, Michigan, Minnesota, Missouri, Montana, Nebraska, New Mexico, New York, North Dakota, South Dakota, Utah, Wisconsin, Wyoming.

NON-TARGET LEPIDOPTERA CAPTURED IN TRAPS BAITED WITH SPRUCE BUDWORM PHEROMONE IN ONTARIO

Traps baited with a 95:5 blend of E:Z-11-tetradecenal, the sex pheromone of the spruce budworm, Choristoneura fumiferana (Clem.), were deployed throughout several summers in Ontario to determine what other Lepidoptera were captured that might be confused with the male C. fumiferana. Eight other species of Tortricidae were captured with sufficient frequency to suggest that they were attracted to the traps: Choristoneura conflictana Wlk. (the large aspen tortrix), six species of Acleris, and one Gretchena species. Of these, C. conflictana can easily be confused with C. fumiferana. The evidence suggests that male C. conflictana were not attracted by the pheromone, but blundered into the traps. They are very similar morphologically to male C. fumiferana, but can be differentiated with care.

SURVEY OF PATHOGENS IN THE LARGE ASPEN TORTRIX, CHORISTONEURA CONFLICTANA (LEPIDOPTERA: TORTRICIDAE), IN ONTARIO AND BRITISH COLUMBIA WITH PARTICULAR REFERENCE TO GRANULOSIS VIRUS

The large aspen tortrix, Choristoneura conflictana Wlk., occurs throughout the range of trembling aspen, Populus trernuloides Michx., in Canada and the eastern United States (Baker 1972). Outbreaks of the insect occur over large areas, but these outbreaks generally collapse in 2 to 3 years. The principal effect of this pest is to reduce growth of aspen, but it causes little tree mortality (Batzer 1972). Prentice (1955) reviewed the history of outbreaks of C. conflictana in Canada from 1912 to 1953 and the natural control factors of the insect. He reported an extensive parasite complement. Dead and apparently diseased insects were examined, but the only pathogen noted was infection of overwintering larvae by the fungus, Beauveria bassiana (Bals .) Vuill.

PARASITOIDS ASSOCIATED WITH THE LARGE ASPEN TORTRIX, CHORISTONEURA CONFLICTANA (LEPIDOPTERA: TORTRICIDAE), IN INTERIOR ALASKA

Twenty-four species of parasitoids were found associated with the large aspen tortrix in interior Alaska. Keys are supplied for determining adults and, in the absence of adults, the parasitoids based on host stage and on late-instar larval remains. Brief biological and descriptive notes are given for each species appearing in the key.