Resistance reduction and cross-resistance of spinosad-resistant Rhyzopertha dominica (Coleoptera: Bostrichidae) and the association between spinosad resistance and maltase activity

Abstract

The lesser grain borer, Rhyzopertha dominica, is a serious stored-products pest mainly controlled by insecticides. Spinosad, an environmentally friendly biological insecticide with low mammalian toxicity, is considered a suitable candidate for R. dominica management. Given the structural similarity of spinosad and maltose, both containing a neutral sugar structure, it was hypothesized that maltase may hydrolyze spinosad, rendering R. dominica resistant to spinosad. In this study, multiple spinosad-resistant strains (RdSR) were used to test the hypothesis.