Effect of RNAi Targeting SeGrx1 on the Cytotoxicity and Insecticide Susceptibility of Camptothecin in Spodoptera exigua

Glutaredoxins (Grxs) are a class of small, heat-stable, acidic proteins which have been implied in various biological activities in cells, including the defense against oxidative stress induced by various biotic and abiotic factors. In this paper, the effects of RNAi targeting SeGrx1 on the cytotoxicity and insecticide susceptibility of camptothecin (CPT) in Spodoptera exigua were investigated. Results showed that the cytotoxicity of CPT to the cells of S. exigua is heightened significantly by the silencing of SeGrx1. In the larvae of S. exigua, the mortality was significantly increased compared to CPT-alone treatment group at 120 h after knocking down the SeGrx1 gene. Taken together, our results confirmed that SeGrx1 in S. exigua played an important role in protecting the cells from the cytotoxicity induced by CPT, and the sensitivity of S. exigua larvae to CPT was increased by the silencing of SeGrx1. Our findings might provide basic information for understanding the function of Grxs and a strategy in insect pest control of RNAi technology combined with pesticides.