Effect of four organochlorine pesticides on the reproduction of freshwater rotifer Brachionus calyciflorus pallas

Effects of four organochlorine pesticides, including dichlorodiphenyltrichloroethane (DDT), dicofol, endosulfan, and lindane, on the reproduction of freshwater rotifer Brachionus calycifiorus were studied by 3-d population growth tests. Compared to the control, dichlorodiphenyltrichloroethane at 0.64 mg/L, dicofol at 0.8 and 1.2 mg/L, endosulfan at 7.0 mg/L, and lindane at 14.0 mg/L all significantly decreased the population growth rate of the rotifers. Dichlorodiphenyltrichloroethane at concentrations higher than 0.16 mg/L, dicofol at concentrations higher than 0.025 mg/L, endosulfan at concentrations higher than 0.875 mg/L, and lindane at 14.0 mg/L all significantly decreased the mictic rate of the rotifers. Dichlorodiphenyltrichloroethane at 0.24 and 0.32 mg/L-increased significantly the fertilization rate, but DDT at 0.64 mg/L inhibited completely the occurrence of fertilized mictic females. Dichlorodiphenyltrichloroethane at 0.32 and 0.64 mg/L, dicofol at 1.2 mg/L, and endosulfan at 7.0 mg/L all significantly decreased the ratio of ovigerous females to nonovigerous females, but the reverse was true for lindane at 7.0 mg/L. Dichlorodiphenyltrichloroethane at 0.0025 and 0.01 mg/L increased significantly the ratio of mictic females to amictic females, but the reverse was true for dicofol at 0.8 mg/L. Both population growth rate and mictic rate of the rotifers were suitable endpoints for assessing the effects of the four organochlorine insecticides on the reproduction of the rotifers, and the latter was more sensitive.