Abstract: To investigate the toxic effects and impacts on antioxidant and immune functions of deltamethrin and lambda-cyhalothrin
on juvenile Eriocheir sinensis, a semi-static acute toxicity test was conducted, where juvenile crabs were exposed to a concentration of 0.905 μg/L for 24, 48, 72, 96 hours, respectively. The activities of total superoxide dismutase （T-SOD）, catalase （CAT）, alkaline phosphatase （AKP）, and acid phosphatase （ACP）, as well as the malondialdehyde （MDA） content, were determined in the hepatopancreas and serum of the juvenile crabs. Results showed that after 24 h of exposure, the T-SOD activity in hepatopancreas of
the lambda-cyhalothrin group was significantly higher than that of the deltamethrin group, while the MDA content in hepatopancreas of the deltamethrin group was significantly higher than the control group. After 48 hours, the T-SOD activity in hepatopancreas of the deltamethrin group was significantly higher than the control group, while MDA content significantly decreased, and serum CAT activity was significantly lower than the control group. In the lambda-cyhalothrin group, serum T-SOD activity significantly increased, and hepatopancreas AKP activity was significantly lower than the control group. After 72 hours, serum T-SOD and CAT activities of the deltamethrin group were significantly lower than the control group. At 96 hours, serum AKP activity in both groups was significantly lower than the control group. In summary, both pyrethroids significantly affect the antioxidant capacity and immune response of juvenile Eriocheir sinensis.

Key words: deltamethrin, lambda-cyhalothrin, Eriocheir sinensis, toxic effects, antioxidant capacity