Many studies have now implicated elevated levels of various esterases and cytochrome P450s in metabolic resistance to synthetic pyrethroids (SPs) and organophosphates (OPs) in Helicoverpa armigera, and a couple of studies have also implicated elevated esterase levels in resistance to the Cry1Ac toxin of Bacillus thuringiensis (Bt). However, excepting one study linking a specific P450 to modest levels of SP resistance, a causal basis for these associations remains to be established. We have been involved in a genome sequencing project for the species, which finds that the genome contains an unusually large number of esterase and P450 genes. This includes one cluster of 21 very closely related esterase paralogues, some members of which proteomic work has previously associated with SP and OP resistance. We describe a set of selection, genetic mapping and expression analyses using the genomic resources that help clarify the role of esterases and P450s in these two resistances. A series of experiments with various Bt resistant lines discounts some lines of evidence associating esterases with Cry1Ac resistance but also supports some other evidence for such an association.

Biochemistry and genomics of insecticide resistance in<i> Helicoverpa</i>

248th National Meeting (2014)

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Biochemistry and genomics of insecticide resistance in Helicoverpa