Toxicity comparison of avermectins, chlorantraniliprole and deltamethrin on Procambarus clarkii: Histopathology,...

Rice-crayfish farming is currently an important ecological farming model for Procambarus clarkii, achieving co-cultivation of animals and plants, which carries great importance for the development of sustainable agriculture. Widely used pesticides in rice cultivation can effectively control the pests, weeds, and diseases. However, it may also pose a threat to the health of P. clarkii through their residues in water. To assess the toxicity of pesticide residues to P. clarkii, the effects of acute exposure for 96 h on P. clarkii were investigated, from the aspects of histopathology, apoptosis, antioxidation, transcriptome response, and intestinal microbiota, using the three pesticides including avermectins (AVMs, biotic pesticide), chlorantraniliprole (CAP, low toxicity chemical pesticide) and deltamethrin (DM, high toxicity chemical pesticide) at the dose of 1 % of 96 h LC₅₀ for each one. Relative to the control (CON) group, distinct pathological damage was observed in the hepatopancreatic and intestinal tissue structure of P. clarkii in the AVMs, CAP and DM groups, including lumen enlargement, vacuolization, epithelial necrosis, and reduced villus height and muscle thickness. Apoptosis-related indicators, like caspase-3 and p53 were significantly higher, while BI-1 expression lower in the pesticide-treated groups. In all the pesticide-treated groups, oxidative stress was evident, as indicated by increased oxygen species (ROS) and malondialdehyde (MDA) levels, along with decreased the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and total antioxidant capacity (T-AOC) in both hepatopancreas and intestine. Transcriptomic analysis identified differentially expressed genes (DEGs) enriched in immune and metabolic pathways, notably the phagosome pathway, across all pesticide treatments. Integration with intestinal microbiota profiling revealed shifts in dominant bacterial phyla in the pesticide-treated groups relative to the CON group, which included a decline in Proteobacteria and a rise in Firmicutes, Klebsiella, and Aeromonas. Correlation analysis suggested that alterations in intestinal microbiota were closely linked to the expression of phagosome-related DEGs, such as TUBA, TUBB, F-actin, and cathepsin L. These findings highlight the disruption of intestinal and hepatic homeostasis in P. clarkii under pesticide exposure and provide insight into host-microbiota interactions at the molecular level.