The essential role of gut microbiota in dsRNA-mediated pest control of the phytophagous ladybird beetle, Henosepilachna vigintioctopunctata.

RNA interference (RNAi) has proven to be an effective measure in combating insect pests. RNA-based pesticides have already made their way to the market for pest control. We previously have demonstrated the pivotal role of gut microbiota in influencing the efficacy of RNAi against the leaf beetle Plagiodera versicolora (Coleoptera), a species highly susceptible to RNAi. However, the role of the gut microbiota in different insect species remains ambiguous. We delved into the intricate interplay between gut bacterial communities and RNAi in the phytophagous ladybird beetle, Henosepilachna vigintioctopunctata (HV), a significant agricultural pest targeting solanaceous plants. By administering double-stranded RNA targeting HV β-Actin gene (dsACT) or utilizing transplastomic (plastid genome transformed) potato plants expressing dsACT on HV axenic larvae, a substantial decrease in lethality was observed compared to non-axenic controls. This underscores the critical role of microbiota in enhancing the effectiveness of RNAi. The disruption of microbial diversity and functionality due to dysbiosis induced by dsRNA feeding amplified physiological stress and mortality rates in HV. Notably, the optimal bacterial densities were crucial for maximizing mortality rates, as elevated concentrations of gut bacteria could disrupt the native microbial equilibrium. These findings underscore the importance of microbiota-aware strategies in RNAi applications, particularly in the context of sustainable pest management within solanaceous crop systems.