Deciphering Pesticide-Induced Gut Microbiota Dysbiosis in Bombyx Mori L. Through 16s Rrna Amplicon Sequencing

The gut microbiota engages in complex interactions with its host, influencing essential physiological processes such as digestion, nutrient assimilation, immunity, and detoxification. Pesticide residues can disrupt this microbial equilibrium by altering the composition and structure of the gut microbial community. The present study investigated the impact of pesticide residues on the gut microbiota of the silkworm, Bombyx mori L., with the objective of determining a safe post-application waiting period. Gut bacteria were isolated from fifth-instar larvae and characterized using morphological and molecular approaches. A total of 74 bacterial isolates were obtained, representing three major phyla: Pseudomonadota (Proteobacteria), Bacillota (Firmicutes) and Bacteroidota (Bacteroidetes). The dominant genera identified were Serratia, Acinetobacter, Bacillus and Chryseobacterium. Phylogenetic analysis grouped the isolates into two major clades corresponding to Proteobacteria and Firmicutes. Exposure to pesticide residues caused significant alterations in the gut microbial community, characterized by a decline in beneficial taxa and an enrichment of pesticide-resistant genera. Temporal analysis revealed that microbial diversity reached its lowest level at 8 days after spraying (DAS) and gradually recovered by 21 DAS, indicating a transient disruption of gut microbial homeostasis. Based on these findings, a safe waiting period of 15/21 days after pesticide application is recommended to minimize adverse effects on gut microbiota and to ensure optimal silkworm health and growth.