miR-23a modulates chlorantraniliprole susceptibility by targeting SfGSTs3 in Spodoptera frugiperda (Smith)

The fall armyworm Spodoptera frugiperda (Smith) can damage many crops distributed worldwide, and chemical insecticide application is the main control strategy. However, the frequent application of insecticides can lead to severe insecticide resistance in S. frugiperda. Glutathione S-transferases (GSTs) play a critical role in insecticide resistance in pests. In this study, it was found that the expression of SfGSTs3 was significantly up-regulated after exposure to chlorantraniliprole. After injection of dsSfGSTs3, the susceptibility of chlorantraniliprole was improved, and microRNA-23a binding on 3'UTR of SfGSTs3 was found. Luciferase reporter assays revealed that the effects of miR-23a on SfGSTs3 expression were suppressed via this binding site in S. frugiperda. Injection of the miR-23a agomir significantly reduced SfGSTs3 expression, together with increased chlorantraniliprole susceptibility. In contrast, injection of the miR-23a antagomir significantly improved SfGSTs3 expression and thus decreased chlorantraniliprole susceptibility in the larvae of S. frugiperda. These findings provide a theoretical foundation for better understanding the posttranscriptional regulation of SfGSTs3 and can be used to further study the mechanism by which miRNAs regulate insecticide susceptibility in pests.