Biological Effects of Pyrimethinal on Aquatic Worms (Tubifex tubifex) Under Laboratory Conditions

Laboratory studies were conducted to determine the effects of different concentrations of pyrimethinal on protein contents, and some oxidative stress in Tubifex tubifex after an exposure of 2, 4, and 7 days. Residues of the fungicide were followed in water and in the worms. In water, pyrimethinal concentration decreased slowly (maximum ?6.4 % ± 0.8 % after 2 days for 25 mg L^?1). In the worms, it increased after 4 days and decreased thereafter. LC₅₀ values were between 49.2 ± 0.58 and 39.5 ± 0.95 mg L^?1 depending on exposure time. The activity of catalase increased in response to the fungicide after 2 days of exposure to 25 mg L^?1 of pyrimethinal (+90 %). The highest decrease of glutathione-S-transferase activity (?29.7 %) was found after 7 days in the presence of 25 mg L^?1.