RNAi effect in target and non-target pests correlates with the length of continuous matches in dsRNA sequences

RNA interference (RNAi) has emerged as a promising and environmentally friendly approach for controlling the pest Henosepilachna vigintioctopunctata (Hvig). Identifying lethal target genes in Hvig and evaluating the efficacy of oral dsRNA administration are crucial steps in this process. Additionally, assessing the potential risks of RNAi to non-target organisms (NTOs) is essential to ensure environmental safety. A soluble N-ethylmaleimide-sensitive factor attachment protein alpha (alpha SNAP) is an essential component of membrane fusion machinery, offering as a potential target gene for RNAi-based pest control. This study found that silencing of Hv alpha snap with varying dsRNA concentrations (6.25, 12.5, 25, 50, 100, 200 ng/mu L) induced 53.33 %-100 % lethality in Hvig, with an LC50 value of 10.15 ng/mu L. Feeding the NTO, Propylaea japonica with dsHv alpha snap or dsPj alpha snap-1 containing 3-21-nt consecutive matches had no notable effects on survival, development, pupal weight, or gene expression. However, injecting these dsRNAs significantly increased P. japonica mortality. A chimeric dsGFP-alpha snap-17-nt suppressed Hv alpha snap expression and reduced Hvig larval survival but failed to induce RNAi in P. japonica. Overall, this study suggests that different species exhibit varying sensitivities to dsRNA, and increasing the number of consecutive matching bases may enhance RNAi effects in NTOs.