Sublethal clothianidin disrupts PI3K-AKT-mTOR homeostasis and induces autophagic-apoptotic imbalance in Bombyx mori.

Unmanned aerial vehicles (UAVs) have improved the operational efficiency of pesticide application. However, off-target droplet drift poses a potential threat to nontarget organisms. Clothianidin is widely applied, yet its sublethal toxicological impacts on nontarget organisms remain poorly characterized beyond neurotoxicity. Here, Bombyx mori larvae were exposed to clothianidin, followed by comprehensive analyses of fat body ultrastructure, biochemical responses, and transcriptomic profiles. Clothianidin exposure impaired larval growth and induced ultrastructural damage in the fat body. Transcriptomic analysis revealed pronounced responses in the fat body, with GO and KEGG analyses indicating disrupted ATP binding along with downregulation of immune and metabolic pathways. Mechanistically, clothianidin exposure perturbed the PI3K-AKT-mTOR signaling pathway, as evidenced by decreased p-AKT and p-4EBP levels. Furthermore, clothianidin induced an autophagic-apoptotic imbalance, as indicated by accumulation of ATG8-PE and ATG6 alongside elevated BmICE expression. Beyond the classical neurotoxicity observed at the synapse, these findings showed that the fat body was preferentially responsive to sublethal clothianidin, with cellular injury linked to PI3K-AKT-mTOR signaling perturbation and autophagy-related stress. This study provided novel mechanistic insights into sublethal neonicotinoid toxicity in silkworms and established a valuable foundation for ecological risk assessment of UAV-based pesticide application.