Integration of Physiological, Biochemical, and Transcriptomic Analyses Reveals the Multifaceted Toxicity of Tricyclazole in <i>Eriocheir sinensis</i>

Tricyclazole (TRCZ), a widely used fungicide in rice-crab coculture, poses a potential risk to the Chinese mitten crab (<i>Eriocheir sinensis</i>). This study aimed to elucidate its hepatopancreatic toxicity mechanism by integrating physiological, biochemical, and transcriptomic analyses. We determined a 96 h LC₅₀ of 54.28 mg/L and a safe concentration of 22.09 mg/L. The effects of subchronic (28 days) and acute (96 h) exposure were investigated in the <i>E. sinensis</i>. TRCZ exposure induced oxidative stress, immune dysregulation, metabolic disruption, and apoptosis, leading to histopathological damage in the hepatopancreas of <i>E. sinensis</i>. Transcriptomic profiling revealed 4809 differentially expressed genes, with the MAPK signaling pathway being significantly enriched. RNA interference targeting <i>Ras</i> confirmed the pivotal role of the Ras-MAPK cascade in mediating TRCZ-induced injury. Our findings reveal the mechanism of TRCZ toxicity and provide an insight for its risk assessment and safe application in rice-crab coculture systems.