Unclassified glutathione‐S‐transferase AiGSTu1 confers chlorantraniliprole tolerance in Agrotis ipsilon

BACKGROUND Chlorantraniliprole (CAP) is a diamide insecticide with high efficacy against many pest insects, including the black cutworm, Agrotis ipsilon. Agrotis ipsilon is a serious pest causing significant yield losses in crops. Glutathione‐S‐transferases (GSTs) belong to a family of metabolic enzymes that can detoxify a wide range of pesticides. However, little is known about the functions of GSTs in CAP tolerance in A. ipsilon. RESULTS A cDNA sequence (designated AiGSTu1) encoding an unclassified GST was identified from A. ipsilon. AiGSTu1 is highly expressed during the 3rd‐instar larval and the pupal stages. Most of the mRNA transcripts were found in larval Malpighian tubules. Exposure to CAP strongly enhanced AiGSTu1 expression, GST activity, hydrogen peroxide (H2O2) and malondialdehyde levels in larvae. H2O2 treatment upregulated the transcription level of AiGSTu1, suggesting that CAP‐induced oxidative stress may activate AiGSTu1 expression. The activity of recombinant AiGSTu1 was inhibited by CAP in a dose‐dependent manner. Metabolism assay results demonstrated that AiGSTu1 is capable of depleting CAP. Overexpression of AiGSTu1 enhanced the tolerance of Escherichia coli cells to H2O2 and the oxidative stress inducer, cumene hydroperoxide. Silencing of AiGSTu1 by RNA interference increased the susceptibility of A. ipsilon larvae to CAP. CONCLUSION The findings of this study provide valuable insights into the potential role of AiGSTu1 in CAP detoxification and will improve our understanding of CAP tolerance in A. ipsilon. © 2023 Society of Chemical Industry. Chlorantraniliprole exposure to insects causes oxidative stress and activates AiGSTu1 expression. Recombinant AiGSTu1 can metabolize chlorantraniliprole and protect against oxidative stress. Silencing of AiGSTu1 increases the susceptibility of Agrotis ipsilon larvae to chlorantraniliprole.