Dietary RNAi toxicity assay suggests α and γ subunits of HvCOPI as novel molecular targets for Henosepilachna vigintioctopunctata, an emerging coccinellid pest

Henosepilachna vigintioctopunctata is a highly polyphagous pest of solanaceous plants in Asia and has been predominantly controlled using synthetic insecticides. The intensive use of insecticides has led to the development of resistance, creating an urgent need for new control strategies, for this insect pest. RNA interference (RNAi) has been explored as a pest management strategy in multiple insect pests. In this study, we explored RNAi as a potential alternative for controlling H. vigintioctopunctata. Based on preliminary research, we hypothesized that HvCOPI, a coat protein complex that facilitates retrograde transport, is a promising novel molecular target for H. vigintioctopunctata control. To test this overarching hypothesis, we examined the toxicity of double-stranded RNAs (dsRNAs) towards H. vigintioctopunctata using dietary RNAi toxicity assays targeting eight HvCOPI subunits, including α-, β-, β′-, γ-, δ-, ε-, ζ-, and Arf1-COPI using in vitro synthesized and bacterially expressed dsRNAs. The results demonstrated that ingestion of dsHvCOPIs induced acute feeding cessation in both larvae and adults, which led to significant mortality. In this study, H. vigintioctopunctata showed similar sensitivity to both types of dsHvCOPIs production. Ingestion of bacterially expressed dsHvαCOPI and dsHvγCOPI led to the highest mortality in both larvae and adults. Interestingly, there was a significant positive relationship between the knockdown efficiency of different HvCOPI subunits and the corresponding mortality on day 2 and 4, respectively. These combined results suggest that α and γ subunits of HvCOPI are promising targets for the development of RNAi-based biopesticides for the management of H. vigintioctopunctata.