SfFPPS genes mediate reproduction and insecticide-induced resurgence in Sogatella furcifera

Farnesyl pyrophosphate synthase (FPPS), a key enzyme in the mevalonate pathway, is essential for juvenile hormone (JH) biosynthesis and plays a critical role in insect development and reproduction. However, its function and regulation in insect pests like Sogatella furcifera remain poorly understood. Three FPPS genes (SfFPPS1, SfFPPS2, and SfFPPS-like) were identified in S. furcifera. SfFPPS1 and SfFPPS2 contain all typical FPPS motifs and cluster with Hemipteran FPPS genes, while SfFPPS-like lacks several conserved motifs and forms a distinct clade. RNAi-mediated knockdown of each gene significantly downregulated SfKr-h1 and SfVg, further impaired ovarian development and reduced fecundity. The expression of all three SfFPPS genes was significantly reduced by the silencing of TOR pathway key genes, SfRheb, SfTOR, and SfS6K. Moreover, the enhanced expression of these genes in female adults under sublethal triazophos (LC₂₅) exposure indicates a potential link between environmental stress and reproductive enhancement. These findings demonstrate the involvement of SfFPPS1, SfFPPS2, and SfFPPS-like in female reproduction and insecticide exposure through the TOR pathway in S. furcifera. This study not only provides new insights into the JH biosynthesis-mediated reproductive control and the molecular basis of insecticide-induced resurgence, but also offers promising targets for pest management.