Characterization of emamectin benzoate resistance in the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae)

Abstract BACKGROUND Plutella xylostella (L.) is a destructive pest of cruciferous crops worldwide that has evolved resistance to many insecticides. Here we examined the mode of inheritance, cross‐resistance profile, and potential mechanisms of emamectin benzoate resistance in a field‐derived strain of P . xylostella from Japan. RESULTS A field‐collected population of P . xylostella , was found to exhibit strong (> 150‐fold) resistance to emamectin benzoate in insecticide bioassays when compared with a laboratory susceptible strain. Genetic analysis showed that resistance is inherited as an autosomal, recessive trait, and is conferred by a single or a few closely linked loci. The emamectin benzoate resistant strain also exhibited resistance to abamectin, lepimectin, chlorantraniliprole, lufenuron, spinetoram, indoxacarb, fipronil, dieldrin, endosulfan and lambda‐cyhalothrin, demonstrating a remarkable multi‐resistance profile. Insecticide bioassays employing inhibitors of detoxification enzymes revealed that piperonyl butoxide (PBO) increased the toxicity of emamectin benzoate in the resistant strain by ten‐fold indicating the potential involvement of cytochrome P450 monooxygenases in avermectin resistance. Furthermore, cloning and sequencing of the primary receptor of avermectins, the GluCl channel, revealed the absence of target‐site mutations in the resistant strain. CONCLUSIONS Our data on the mode of inheritance and mechanisms of resistance to emamectin benzoate in a P . xylostella strain from Japan provide a foundation for the development of regional resistance management strategies. However, the high levels of phenotypic resistance in this strain to a diverse range of other insecticide classes available for control illustrate the challenges associated with the sustainable control of this important pest. © 2023 Society of Chemical Industry.