Functional Characterization of an α‑Esterase Gene Associated with Malathion Detoxification in <i>Bradysia odoriphaga</i>

Carboxylesterases (CarEs) are a multigene superfamily of metabolic enzymes involved in metabolic detoxification of xenobiotics. In this study, an α<i>-</i>esterase gene (<i>BoαE1</i>) was identified from <i>Bradysia odoriphaga</i>. Phylogenetic analysis classified <i>BoαE1</i> into the <i>α-</i>esterase clade. Developmental expression analysis indicated that <i>BoαE1</i> was significantly expressed in the second to fourth larval stages. Tissue-specific expression analysis indicated that <i>BoαE1</i> was highly expressed in the larval midgut. After exposure to LC₃₀ of malathion, the CarE activity of <i>B. odoriphaga</i> was induced and the transcriptional level of <i>BoαE1</i> was significantly up-regulated. Silencing of <i>BoαE1</i> significantly increased the susceptibility of <i>B. odoriphaga</i> larvae to malathion. Inhibition assays <i>in vitro</i> indicated that malathion significantly inhibited BoαE1 activity. GC-MS assay showed that BoαE1 possesses hydrolase activity toward malathion and participates in the detoxification of malathion. These results strongly suggest that <i>BoαE1</i> plays a crucial role in detoxification of malathion in <i>B. odoriphaga</i>.