Assessing RNAi feasibility and susceptibility to environmental RNAi in Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae)

Trichogramma, a genus of egg parasitoid wasps, are widely used as biological control agents and serve as model organisms in parasitoid research. Despite their significance, the understanding of RNA interference (RNAi) in Trichogramma remains very limited. In this study, we investigated RNAi-associated genes by bioinformatic approaches and experimentally assessed the feasibility of RNAi and the susceptibility of environmental RNAi in Trichogramma. We found that Trichogramma genomes contain a complete set of genes in the RNAi pathway and exhibit extensive gene expansion of dsRNase, which may influence RNAi efficiency by degrading dsRNA. We demonstrated successful RNAi through pupal microinjection in T. dendrolimi Matsumura, providing a technical approach for future gene functional studies. In addition, we observed no evidence of susceptibility to environmental RNAi in either T. dendrolimi adults or larvae, which might be attributed to the extensive expansion of dsRNase. This low environmental RNAi sensitivity in Trichogramma could suggest a reduced risk of RNAi-based pest management strategies affecting nontarget Trichogramma populations. Overall, this study presents a technical approach for conducting gene functional studies in Trichogramma and provides a foundation for evaluating the nontarget effects of RNAi-based pest control strategies on Trichogramma.