Carboxylesterase genes in nitenpyram-resistant brown planthoppers,Nilaparvata lugens

Carboxylesterases (CarEs) represent one of the major detoxification enzyme families involved in insecticide resistance. However, the function of specific CarE genes in insecticide resistance is still unclear in the insectNilaparvata lugens(Stal), a notorious rice crop pest in Asia. In this study, a total of 29 putative CarE genes inN. lugenswere identified, and they were divided into seven clades; further, the beta-esterase clade was significantly expanded. Tissue-specific expression analysis found that 17 CarE genes were abundantly distributed in the midgut and fat body, while 12 CarE genes were highly expressed in the head. The expression of most CarE genes was significantly induced in response to the challenge of nitenpyram, triflumezopyrim, chlorpyrifos, isoprocarb and etofenprox. Among these, the expression levels ofNlCarE2,NlCarE4,NlCarE9,NlCarE17andNlCarE24were increased by each insecticide. Real-time quantitative polymerase chain reaction and RNA interference assays revealed theNlCarE1gene to be a candidate gene mainly involved in nitenpyram resistance, while simultaneously silencingNlCarE1andNlCarE19produced a stronger effect than silencing either one individually, suggesting a cooperative relationship in resistance formation. These findings lay the foundation for further clarification of insecticide resistance mediated by CarE inN. lugens.

Automated summary

Carboxylesterases (CarEs) are an important detoxification enzyme family in insecticide resistance, with specific genes in the insect Nilaparvata lugens being identified and shown to be induced by various insecticides. Tissue-specific expression analysis showed certain CarE genes are highly expressed in the midgut and fat body, while others are more highly expressed in the head. The NlCarE1 gene was identified as a main candidate gene for nitenpyram resistance, with evidence suggesting a cooperative relationship with NlCarE19 in resistance formation. These findings provide a foundation for further understanding of insecticide resistance mediated by CarE in N. lugens.