Unraveling Key Amino Acid Residues Crucial for PxGSTs1 Conferring Benzoylurea Insecticide Resistance in Plutella xylostella

The widespread use of benzoylurea insecticides (BUs) has led to significant resistance issues in various agricultural pests. Previous studies have demonstrated that the overexpression of sigma glutathione S-transferase 1 (PxGSTs1) can confer resistance to novaluron in Plutella xylostella; however, the underlying molecular mechanism remains unclear. This study investigates the role of glutathione S-transferase PxGSTs1 in mediating resistance to BUs in P. xylostella. Using a combination of RNA interference and transgenic Drosophila models, we demonstrated that the overexpression of PxGSTs1 significantly contributes to the resistance against BUs. Functional assays revealed that PxGSTs1 binds to these insecticides with varying affinities. Structural analysis through homology modeling and molecular docking identified the importance of hydrogen bonding and pi–pi stacking in resistance mechanisms. Site-directed mutagenesis confirmed the critical role of Ser65 and Tyr97 in these interactions. Our findings provide a molecular basis for the development of novel BUs and inform strategies for managing BU resistance in P. xylostella.