Esterase-based metabolic resistance to insecticides in heliothine and spodopteran pests

Elevated esterase activities and increased band intensities of multiple esterase isozymes after electrophoresis are commonly associated with resistance to organophosphate, pyrethroid and carbamate insecticides in various heliothine and spodopteran pests. One possible explanation for this involves a 'master regulator' mutation in a more general chemical stress response. An association between elevated esterase activities and isozyme intensities has also been reported for resistance to the Cry1Ac toxin of Helicoverpa armigera. The basis for this is unclear albeit some involvement of esterases could be mediated by the toxin's affinity for N-acetyl galactosamine glycans on certain gut-expressed esterases in this species. (C) Pesticide Science Society of Japan