Effective target genes for RNA interference‐based management of the cabbage stem flea beetle

Abstract

AbstractThe cabbage stem flea beetle (CSFB, Psylliodes chrysocephala) is a key pest of oilseed rape. The ban on neonicotinoids in the European Union due to environmental concerns and the emergence of pyrethroid‐resistant populations have made the control of CSFB extremely challenging. In search of a solution, we have recently shown that RNA interference (RNAi) has potential in the management of CSFB. However, the previously tested target genes for RNAi‐mediated pest control (subsequently called target genes) exhibited moderate and slow‐acting lethal effects. In this study, 27 double‐stranded RNAs (dsRNAs) were orally delivered to identify highly effective target genes in CSFB adults by leveraging the findings of a genome‐wide RNAi screen in Tribolium castaneum. Our screen using 500 ng of dsRNA identified 10 moderately effective (> 50% mortality) and 4 highly effective target genes (100% mortality in 8–13 days). The latter mainly included proteasome subunits. Gene expression measurements confirmed target gene silencing and dose–response studies revealed LD50 values as low as ~20 ng in 14 days following a single exposure to dsRNA. Four highly effective dsRNAs also inhibited leaf damage (up to ~75%) and one affected locomotion. The sequences of promising target genes were subjected to in silico target prediction in non‐target organisms, for example, beneficials such as honeybees, to design environmentally friendly dsRNAs. Overall, the study provides valuable insights for the development of dsRNA‐based insecticides against CSFB.