Effects of novaluron exposure on cocooning and transcriptional changes of genes in silk gland of silkworm, Bombyx mori

As a representative species of Lepidoptera, the silkworm (Bombyx mori) serves as both a model organism and an insect of economic importance. The abundant genetic mutation resources of silkworms provide a critical foundation for related studies. Globally, exposure to various pesticides often leads to failure in cocooning or direct mortality in silkworms. However, systematic investigations into the effects of novaluron exposure on silkworm growth, development, cocooning, and gene expressions are still lacking. This study revealed that novaluron exposure induced significant signs of intoxication in silkworms, accompanied by reductions in body weight and cocoon quality. Furthermore, novaluron exposure caused histopathological damage to the silk gland, reduced the cocooning rate, and significantly downregulated the expression of genes related to silk protein synthesis. Concurrent alterations were observed in the transcriptional levels of genes associated with the PI3K/Akt and CncC/Keap1 signaling pathways. In addition, novaluron exposure upregulated the relative expression levels of detoxification enzyme genes and enhanced corresponding enzymatic activities. These findings provided further insights into the response mechanisms of silkworms to novaluron exposure.