Sublethal chlorantraniliprole exposure induces autophagy and apoptosis through disrupting calcium homeostasis in the silkworm Bombyx mori

The intensive application of chlorantraniliprole (CAP) leaves residues in the environment, posing a potential threat to non-target organisms. In the present study, we investigated the adverse effects of sublethal CAP exposure on Bombyx mori. Sublethal CAP (0.02 mg/L) was shown to induce the release of intracellular CA²⁺ in BmN cells. Meanwhile, CA²⁺ -dependent genes were induced in the midgut at 72 h after CAP (0.01 mg/L) exposure, and damaged mitochondria, autophagosomes, nuclear membrane rupture and condensed chromatin were observed. Moreover, the key genes in the Oxidative Phosphorylation pathway were significantly down-regulated. The transcript levels of autophagy-related genes ATG6 and ATG8 were significantly up-regulated, and the protein levels of LC3-II and Atg7 were significantly increased by 3.72- and 3.33-fold, respectively. Additionally, the transcript levels of the upstream genes in the Apoptosis pathway (calpain and Apaf-1) were significantly up-regulated, the protein levels of the downstream gene Caspase 3 and its cleaved form were significantly up-regulated by 1.97- and 4.55-fold, respectively, consistent with the elevated Caspase 3 activity at 72 h. Collectively, these findings demonstrate that intracellular CA²⁺ release induced by sublethal CAP inhibits Oxidative Phosphorylation pathway, which causes mitochondrial dysfunction, leading to Autophagy and Apoptosis in the midgut of B. mori.