Characterization of the insecticide detoxification carboxylesterase Boest1 from Bradysia odoriphaga Yang et Zhang (Diptera: Sciaridae)

BACKGROUND In insects, carboxylesterases (CarEs) are enzymes involved in the detoxification of insecticides. However, the molecular mechanism of CarE-mediated insecticide metabolism in Bradysia odoriphaga, a serious agricultural pest, remains unclear. The aim of this study is to investigate the detoxification process of malathion, bifenthrin, and imidacloprid by B. odoriphaga carboxylesterase (Boest1). RESULTS An alpha class CarE gene Boest1 was cloned from B. odoriphaga. The results of real-time quantitative polymerase chain reaction showed that Boest1 is up-regulated with age during the larval stage, and the level of transcription of Boest1 is higher in the midgut and Malpighian tubule than in other tissues. The expression level of Boest1 was significantly increased after exposure to malathion and bifenthrin. Recombinant BoEST1 expressed in vitro showed high catalytic activity toward alpha-naphthyl acetate, which was substantially inhibited by malathion and triphenyl phosphate. The in vitro metabolism assays showed that BoEST1 demonstrates hydrolytic capacity toward malathion and bifenthrin but not imidacloprid. The binding free energy analysis indicates that BoEST1 has a higher affinity for malathion and bifenthrin than imidacloprid. CONCLUSION These results suggest that BoEST1 plays a role in the breakdown of insecticides and may be involved in the development of resistance in the Chinese chive pest B. odoriphaga; our findings also provide data for better pest management and perspectives for new pesticides development.

Automated summary

The study found that Boest1 expression levels in Chinese chive pests are age-dependent, with higher transcription levels in the midgut and Malpighian tubule during larval stages. Exposure to malathion and bifenthrin increased the expression of Boest1 significantly. BoEST1 exhibited strong catalytic activity towards alpha-naphthyl acetate in vitro, which was inhibited by malathion and triphenyl phosphate.