Transcription factor B‐H2 regulates CYP9J34 expression conveying deltamethrin resistance in Culex pipiens pallens

Abstract BACKGROUND Mosquitoes are vectors of various diseases, posing significant health threats worldwide. Chemical pesticides, particularly pyrethroids like deltamethrin, are commonly used for mosquito control, but the emergence of resistant mosquito populations has become a concern. In the deltamethrin‐resistant (DR) strain of Culex pipiens pallens , the highly expressed cytochrome P450 9 J34 ( CYP9J34 ) gene is believed to play a role in resistance, yet the underlying mechanism remains unclear. RESULTS Quantitative polymerase chain reaction with reverse transcription (qRT–PCR) analysis revealed that the expression of CYP9J34 was 14.6‐fold higher in DR strains than in deltamethrin‐susceptible (DS) strains. The recombinant production of CYP9J34 protein of Cx. pipiens pallens showed that the protein could directly metabolize deltamethrin, yielding the major metabolite 4′‐OH deltamethrin. Through dual luciferase reporter assays and RNA interference, the transcription factor homeobox protein B‐H2 ‐like ( B‐H2 ) was identified to modulate the expression of the CYP9J34 gene, contributing to mosquito resistance to deltamethrin. CONCLUSIONS Our findings demonstrate that the CYP9J34 protein could directly degrade deltamethrin, and the transcription factor B‐H2 could regulate CYP9J34 expression, influencing the resistance of mosquitoes to deltamethrin. © 2023 Society of Chemical Industry.