RNAi assays in the striped flea beetle (Phyllotreta striolata) suggest Ps-COPI and PsArf1COPI as potential molecular targets for pest control

Phyllotreta striolata (Fabricius), commonly known as the striped flea beetle (SFB), is a notorious insect pest that attacks Brassicaceae plants worldwide, leading to tremendous economic losses. RNA interference (RNAi) has been proposed as a promising strategy for sustainable and eco-friendly pest control. In this study, a total of nine housekeeping genes including PsVATPA, PsHSP90, PsEF1A, PsRPL6, PsRPS24, PsActin, PsTUBA, PsRPS18, and PsRPL4 were evaluated under four different conditions (organization, population, sex, and RNAi). PsEF1A and PsVATPA were identified as the best reference genes for RNAi bioassay. Furthermore, a total of 24 target genes were selected to investigate their RNAi effects in SFB adults with double-stranded RNAs (dsRNAs), five of them showed significant mortality (28.00% to 70.00%), namely Ps alpha-COPI, Psi-COPI, PsRPS18, Ps gamma-COPI, and PsArf1COPI. We found that gene transcript levels of the two most lethal genes, Ps gamma-COPI and PsArf1COPI, were significantly decreased after treated with the target dsRNAs either by feeding or injection method. The findings from this study demonstrated that the introduction of dsRNAs via oral feedings or injection induces the RNAimediated silencing of target genes and can lead to insect mortality. Overall, the identified target genes can be explored in developing RNAi-based insecticides for SFB control.