Abstract

BACKGROUND Insecticide resistance continuously poses a threat to agricultural production. Chemosensory protein-mediated resistance is a new mechanism of insecticide resistance discovered in recent years. In-depth research on resistance mediated by chemosensory proteins (CSPs) provides new insight into aid insecticide resistance management. RESULTS Chemosensory protein 1 in Plutella xylostella ( PxCSP1 ) was overexpressed in the two indoxacarb-resistant field populations and PxCSP1 has a high affinity with indoxacarb. PxCSP1 was upregulated when exposed to indoxacarb and the knockdown of this gene elevated sensitivity to indoxacarb, which demonstrate that PxCSP1 is involved in the indoxacarb resistance. Considering that CSPs may confer resistance in insects via binding or sequestering, we explored the binding mechanism of indoxacarb in PxCSP1 -mediated resistance. Using molecular dynamics simulations and site-directed mutation, we found that indoxacarb forms a solid complex with PxCSP1 mainly through van der Waals interactions and electrostatic interactions. Between these, the electrostatic interaction provided by the Lys100 side chain in PxCSP1 , and especially the hydrogen bonding between the NZ atom and the O of the carbamoyl carbonyl group of indoxacarb, are the key factors for the high affinity of PxCSP1 to indoxacarb. CONCLUSIONS The overexpression of PxCPS1 and its high affinity to indoxacarb is partially responsible for indoxacarb resistance in P. xylostella . Modification of indoxacarb's carbamoyl group has the potential to alleviate indoxacarb resistance in P. xylostella . These findings will contribute to solving chemosensory protein-mediated indoxacarb resistance and provide a better understanding of the insecticide resistance mechanism. © 2023 Society of Chemical Industry.