Biochemical and molecular disruptions in hook snout carp induced by co-exposure to lambda-cyhalothrin and difenoconazole

Pesticides are recognized as prominent toxicants in aqueous ecosystems, which frequently impact aquatic life. The pyrethroid insecticide lambda-cyhalothrin (LDC) and the triazole fungicide difenoconazole (DFC) are frequently co-detected in many water sources. However, the joint harmful effects of these chemicals on fish are still poorly understood. In this study, a 30-day co-exposure experiment was conducted using LDC and DFC on the hook snout carp (Opsariichthys bidens) to assess their toxic impacts on hepatic tissues. Biochemical assays demonstrated a significant increase in catalase (CAT) and caspase-3 (CASP-3) activities of hepatic cells following exposure to either LDC or DFC alone, as well as their combination. Notably, the combined exposure group exhibited a more pronounced elevation in these enzymatic activities compared to individual exposures, suggesting enhanced oxidative stress and mitochondrial dysfunction. At the molecular level, exposure to both pesticides, either individually or in combination, caused erβ1 and socs3a to be downregulated and cxcl-c1c to be upregulated. Consistent with the biochemical findings, the combined exposure had a more substantial impact on gene expression than the individual exposures, indicating heightened immunotoxic and endocrine-disrupting effects. The synergistic interaction between LDC and DFC suggested that their co-presence exacerbates toxicity in fish liver, revealing underlying mechanisms of oxidative damage, mitochondrial impairment, and immune dysregulation. These findings provide insightful knowledge that could inform chemical regulatory guidelines for pesticide application and management in agricultural settings, aiming to mitigate the environmental impact of these commonly used agrochemicals.