关键词: 韭菜迟眼蕈蚊, 辛硫磷, 羧酸酯酶, RNA干扰, 解毒代谢

Abstract: Bradysia odoriphaga is a major pest of Chinese chive and has developed resistance to the commonly used organophosphorus insecticide phoxim.To elucidate the detoxification mechanism of B.odoriphaga against phoxim，a combination of methods including carboxylesterase‐specific inhibitor synergism assay，quantitative real‐time PCR，RNA interference（RNAi），and in vitro inhibition assay were employed.The results showed that under exposure to the 30% lethal concentration（LC₃₀）of phoxim，carboxylesterase activity in third‐instar larvae increased significantly.The carboxylesterase activities at 12，24，36，and 48 h post‐treatment were 40.03，32.91，30.03，and 27.98 μmol/（mg·min），representing 2.44‐，1.68‐，1.58‐，and 1.82‐fold increases compared to the blank control.Following treatment with the specific carboxylesterase inhibitor triphenyl phosphate（TPP），the mortality of the larvae reached 41.67%，which was 8.34 percentage points higher（a relative increase of 25.0%）than the control group not fed with TPP.Under phoxim stress，the expression level of the carboxylesterase gene BoαE1 was significantly up‐regulated. Knockdown of BoαE1 by RNAi resulted in a corrected mortality rate of 56.25%，representing a 30.44 percentage point increase（a relative increase of 117.9%）compared to the control larvae without gene silencing.In vitro inhibition assays further demonstrated that phoxim inhibited the activity of the recombinant BoαE1 protein with a half‐maximal inhibitory concentration（IC₅₀）of 4.020×10^-4 mg/L. In conclusion，the carboxylesterase gene BoαE1 is involved in
the detoxification metabolism of phoxim in B.odoriphaga and plays a crucial role in the development of resistance to organophosphorus insecticides.

Key words: Bradysia odoriphaga, Phoxim, Carboxylesterase, RNAi, Detoxification metabolism