Study on Cross-resistance between BPU-type IGRs and Other Insecticides Including Bacillus thuringiensis and Abamectin in the Diamondback Moth, Plutella xylostella L.

Abstract

Investigation of cross-resistance of diamondback moth(DBM), Plutella xylostella L., which resisted to benzoylphenyl urea(BPU)-type insect growth regulator (IGR), among four organophosphorus insecticides, two carbamates, two synthetic pyrethroids, four IGRs, Thuricide and Abamectin was conducted us this study. The IGR-selected strains did not show strong cross-resistance to test insecticides except carbofuran. A relatively high resistance to synthetic pyrethroids was recorded as synthetic pyrethroid resistance of the DBM is an existing phenomenon in Taiwan. All IGR-resistant strains were still highly sensitive to Thuricide and Abamectin. Cross-resistance among different IGRs is significant in different amplitudes. Hexaflumuron was the least affected by IGR cross-resistance and followed by chlorfluazuron, while flufenoxuron and teflubenzuron confronted with the most serious cross-resistance problem. The IGR-resistance in DBM is chemical structure-related. Analyses of structure-activity relationship in both susceptible and resistant strains indicated both 3,5-dichloro-and a large side moiety at position-4 on the phenyl ring of BPU are beneficial to reduce the IGR-resistance in DBM.