Gao_2026_Pestic.Biochem.Physiol_222_107212

Bradysia odoriphaga is a major underground pest in northern China. Esterases are key detoxifying enzymes involved in the metabolism of various insecticides. This study explores the role of alpha-esterases in detoxifying chlorpyrifos in B. odoriphaga. Exposure to the LC(30) concentration of chlorpyrifos significantly increased carboxylesterase (CarE) activity in B. odoriphaga. Using the esterase inhibitor triphenyl phosphate (TPP) made B. odoriphaga more vulnerable to chlorpyrifos. A total of 28 esterase genes were identified from the transcriptome database of B. odoriphaga. Phylogenetic analysis classified eight of these genes with the microsomal alpha-esterases common in lower dipterans. Silencing five genes-BoalphaE1, BoalphaE4, BoalphaE5, BoalphaE6, and BoalphaE7-markedly increased the insects' susceptibility to chlorpyrifos. RT-qPCR results showed that all five genes were upregulated after exposure to the LC(30) dose of chlorpyrifos. In vitro experiments demonstrated that recombinant BoalphaE1, BoalphaE4, and BoalphaE7 could bind to chlorpyrifos. Following high-temperature treatment, chlorpyrifos levels returned to the control levels. Molecular docking confirmed that BoalphaE1 and BoalphaE4 bind to chlorpyrifos, with BoalphaE1 having a stronger affinity. These results suggest that alpha-esterases play a vital role in B. odoriphaga's resistance to chlorpyrifos, likely by sequestering the insecticide.