Toxicity Effects and Mechanism of Chemical Stress on Pomacea canaliculata

Pomacea canaliculata, as a significant invasive alien species, poses severe threats to agricultural development. Currently, chemical applications demonstrate notable efficacy in controlling this pest. However, metaldehyde exhibits overly singular toxicity towards P. canaliculata; niclosamide sulfate is not a molluscicide; and fentin acetate is a fungicide. Currently, these findings fail to elucidate the physiological and biochemical effects of the compounds after they enter the P. canaliculata’s body. In this study, we evaluated the toxicity of metaldehyde (ME), niclosamide sulfate (NS), and fentin acetate (FA) against P. canaliculata and analyzed the morphological and physiological changes in response to chemical stress. The results indicated that three chemicals exhibited potent molluscicidal activity, especially in the NS treatment group. After 12 h exposure to LC50 concentrations (48 h LC50), the surface area of livers was reduced significantly by 12.1%, 13.9%, and 2.8% compared to the control group, while the kidneys expanded significantly by 6.4%, 3.2%, and 16.7%, respectively. The heart showed marked enlargement by 152.1% and 44.2% under niclosamide sulfate and metaldehyde treatments. The pulmonary sac significantly contracted by 23.6% under niclosamide sulfate stress but expanded by 6.1% under fentin acetate exposure. The stomach enlarged significantly after niclosamide sulfate treatment, whereas it shrank by 2.1% and 5.7% under metaldehyde and fentin acetate treatments, respectively. Metabolomic analysis of liver tissues revealed 553, 99, and 585 differential metabolites compared to the control group, respectively. KEGG pathway enrichment analysis showed that the metabolism pathway, lysine degradation, and bile secretion are likely related to the response to chemical stress in P. canaliculata. Further examination showed a significant decrease in total protein content and the activities of malondialdehyde (MDA), acetylcholinesterase (AChE), superoxide dismutase (SOD), and catalase (CAT) under chemical stress. These findings enhance our understanding of the targeted mechanisms of molluscicides against P. canaliculata. Metaldehyde may exert neurotoxic effects on the P. canaliculata, while niclosamide sulfate may interfere with its respiratory system. Additionally, both chemicals affect metabolic pathways in the snail’s liver, including lipid metabolism and metabolic pathways associated with energy metabolism. These findings provide valuable insights for designing a novel snail control agent and formulating scientific management strategy.