Potential toxicity and dietary risk of tricyclazole to Chinese mitten crab (Eriocheir sinensis) in the rice-crab co-culture model.

Tricyclazole is used as a common fungicide to control rice blast. However, studies on the toxicity of tricyclazole to crabs in the rice-crab co-culture system are still extremely rare. Here, the environmental dissipation of tricyclazole was monitored in this model, and the potential toxicity of tricyclazole to E. sinensis at environmental concentrations as well as the dietary risk was evaluated. The results showed that tricyclazole had no significant acute toxicity to E. sinensis (LC50 > 100 mg/L), while it promoted body weight gain. Tricyclazole in the hepatopancreas had a higher persistent bioaccumulation risk than in the muscle. Tricyclazole suppressed the immune response of E. sinensis under prolonged exposure and there should be gender differences, with females being more sensitive. Lipid metabolism enzymes were also significantly inhibited. While tricyclazole stimulated males molting but prolonged molting duration, both molting and duration of females were also disturbed. The dietary risk assessment indicated that tricyclazole intake from current crab consumption was low risk. This evidence demonstrated that tricyclazole may have potential risks to individual development, nutritional quality, and economic value on E. sinensis and should be used with caution in rice-crab co-culture system whenever possible.