Efficacy of the insect growth regulators tebufenozide and fenoxycarb for lepidopteran pest control in apples, and their compatibility with biological control for integrated pest management.

The insect growth regulators tebufenozide and fenoxycarb were compared with the industry standard organophosphate, azinphos-methyl, in a replicated field trial. In both the 1992-93 and 1993-94 seasons, the 2 insect growth regulators maintained damage levels to harvested and windfall apples below 1% for both codling moth (Cydia pornonella L.) and lightbrown apple moth (Epiphyas postvittana Walker). This was despite considerable pest pressure as indicated by pheromone trap catches of both species. In the first season of the trial, E. postvittana was controlled more effectively (P<0.05) by tebufenozide than by fenoxycarb. In both seasons, populations of two-spotted mite, Tetranychus urticae Koch, and European red mite, Panonychus ulmi Koch, were higher in plots under azinphos-methyl treatment than in either insect growth regulator treatment. Neither insect growth regulator appeared to suppress populations of the phytoseiids Typhlodromus pyri Scheuten and Typhlodromus occidentalis Nesbitt. Limb jarring in the second season showed statistically significant (P<0.05) differences in populations of other predators which may have contributed to the biological control of phytophagous mites in the insect growth regulator treatments. Numbers of spiders, Stethorus spp., and apple dimpling bug (Carnpylomma liebknechti Girault) nymphs were all lower in the azinphos-methyl treatment. Results are discussed in relation to reducing dependence on conventional pesticides by use of more target-specific compounds which may be more compatible with biological control.