Endophytic Fusarium commune G3-29-Mediated dsRNA Delivery for Efficient Control of Western Flower Thrips

RNA interference (RNAi) provides a sequence-specific strategy for pest management, but efficient and stable double-stranded RNA (dsRNA) delivery remains a key challenge. Here, we established a plant-probiotic-based gene silencing system using the endophytic fungus Fusarium commune G3-29 as a dsRNA delivery vector against western flower thrips (WFTs, Frankliniella occidentalis). Recombinant G3-29 strains expressing dsRNA targeting the essential WFT genes ACT and SNF were constructed and confirmed to colonize kidney bean leaves without pathogenicity. Bioassays showed that feeding on leaves colonized by dsRNA-expressing G3-29 significantly decreased survival and downregulated target gene expression in both WFT larvae and adults. Within 4 days, survival of both larvae and adults fell below 10%. In larvae, target gene expression decreased by 63% (ACT) and 33% (SNF), while in adults, reductions of 74% (ACT) and 65% (SNF) were observed. In contrast, in vitro-synthesized dsRNA failed to induce significant gene silencing or mortality in larvae, and its control efficacy against adults was also inferior to that of endophytic fungus-mediated dsRNA delivery. Our findings establish endophytic fungus F. commune G3-29 as an effective and sustainable dsRNA delivery vehicle for RNAi-based pest control, offering distinct advantages over existing strategies such as HIGS and SIGS. This approach provides a promising new direction for managing WFTs and other insect pests.