Effects of Double-Stranded RNA Degrading Nucleases on RNAi Efficiency in Beet Moth Spodoptera exigua (Lepidoptera: Noctuidae)

The insect order Lepidoptera contains many species that are considered to be agricultural pests. Specific double-stranded RNA-degrading enzymes in some moth species decrease the efficiency of RNA interference (RNAi). RNAi refers to the efficient and specific degradation of homologous mRNA induced by highly conserved, double-stranded RNA during evolution. The dsRNase enzymes can specifically recognize exogenous dsRNA, and bind to and degrade dsRNA, resulting in the inability of dsRNA to play its role. Although dsRNases play an important role in dsRNA degradation, there has been limited research on these enzymes. In this study, we successfully identified four genes related to dsRNases (named SeRNase1, SeRNase2, SeRNase3 and SeRNase4) from the genome of Spodoptera exigua. To overcome the rapid degradation of dsRNA in the midgut of S. exigua, we combined nanotechnology with biology and developed a new strategy to administer RNAi to insect pests. This binding block directed contact between the dsRNA and SeRNases to improve the efficiency of RNAi in suppressing gene expression. We demonstrate the potential of using nanotechnology to provide a novel RNAi delivery method for pest control.