Role of insecticide-mediated transcription of the TOR and JH signaling pathway-related genes in the regulation of reproduction in Sogatella furcifera

Sublethal concentrations of insecticides can affect the population dynamics of insects by inducing changes in their reproductive traits; however, the underlying molecular mechanisms remain unclear. In previous transcriptomic experi-ments, triazophos was found to promote SfTOR transcription. Therefore, in this study, two representative insecticides, thia-methoxam (inhibiting reproduction) and triazophos (stimulating reproduction), were selected to evaluate the transcription of the key genes involved in the target of rapamycin (TOR) and juvenile hormone (JH) pathways under stress in Sogatella furcifera. The results showed that thiamethoxam could significantly inhibit the transcription of SfRheb, SfTOR, SfS6K, and SfHMGR, whereas triazophos significantly promoted the transcription of SfRheb, SfTOR, SfS6K, SfHMGR, SfMet, and SfKr-h1. Moreover, RNA interference (RNAi) technology was used to target and silence TOR signaling pathway-related genes. The results showed that RNAi-mediated silencing of SfRheb, SfTOR, and SfS6K significantly inhibited ovarian development and fecundity. The transcription of JH signaling pathway-related genes (i.e., SfHMGR, SfFAMeT, SfMet, and SfKr-h1) and SfVg was significantly inhibited. However, the effects of SfRheb and SfTOR silencing on female reproduc-tion were partially mitigated by the JH analog methoprene. These results indicate that the TOR signaling pathway can regulate the JH signaling pathway and SfVg transcription. In addition, insecticide stress can influence the transcription of TOR signaling pathway-related genes and transduction of stress signals via the JH signaling pathway, thereby affecting the transcription of SfVg and ultimately regulating reproduction in females.