Multiple effects of tebufenozide on the survival and performance of the spruce budworm (Lepidoptera: Tortricidae)

Aerial application of Mimic (R) 2LV to rising outbreak populations of the spruce budworm (Choristoneura fumiferana (Clemens); Lepidoptera: Tortricidae) in Quebec, Canada, resulted in high levels of population reduction at spray deposits of 0.5-1.2 mu g tebufenozide/g of foliage. Application to potted host trees in outdoor enclosures followed by bioassays revealed multiple effects on spruce budworm survival and recruitment. Chronic (14-day) exposure of late-instars to treated foliage reduced larval survival and also pupal survival, mating success, and fecundity, depending on the product concentration applied. Treatments that produced foliar deposits of similar to 0.5-1.5 mu g tebufenozide/g caused high larval mortality. Exposure to deposits of similar to 0.15-0.5 mu g/g caused delayed mortality during the pupal stage and reduced the mating success of survivors, while exposure to similar to 0.07-0.15 mu g/g reduced the fecundity of mated females. Sublethal exposure did not affect the progeny of survivors, either in egg hatch, survival during diapause, or survival and performance after diapause. Reduced survival during late-larval and pupal stages combined with lower recruitment as a result of reduced mating success and fecundity are likely to play a role in the suppression of Mimic (R)-treated spruce budworm populations in the years following treatment.