| The effects of deltamethrin, DDT, dicofol and endosulfan on the experimental population dynamics of B. calyciflorus were studied using the life-table technique and population cumulative culture method, and with 17β-estradiol as the positive control. The main results were presented as the following:1 By means of life-table technique, the effect of deltamethrin whose experimental concentrations were 0.6, 1.2, 1.8, 2.4, 3.0 and 3.6mg/L on experimental population dynamics of freshwater rotifer B. calyciflorus was studied at 25℃and with 3.0×106cells/ml of alga Scenedesmus obliquus as the rotifer's food. The results showed that deltamethrin shortened the survival time, and lowered the fecundity of the rotifer. When the concentration of deltamethrin was 3.6mg/L, the survival time and fecundity of the rotifer were the shortest and lowest, and was 72 h and less than 1offspring/female/8h, respectively. Compared to the control, deltamethrin ranged from 0.6 to 3.0mg/L prolonged the pre-reproductive period significantly from (16.48±0.30)h to (20.95±0.97)h, except 1.2mg/L of deltamethrin at which the pre-reproductive period was (15.83±0.29)h. The reproductive periods of the rotifer treated with 0.6 and 1.2mg/L of deltamethrin were respectively (89.83±2.30)h and (106.58±4.88)h, and were significantly longer than that of the control which was (78.29±2.89)h; while those treated with 2.4 and 3.0mg/L of deltamethrin were respectively (70.13±2.61)h and (48.14±2.52)h, and were significantly shorter than that of the control. 1.2mg/L of deltamethrin lengthened the mean life span significantly. The life expectancy, generation time, net reproductive rate and intrinsic rate of population increase of the rotifers decreased respectively from (135.62±6.37)h, (58.81±1.62)h, (28.47±0.59)ind. and (0.0802±0.0026)/h to (81.39±5.04)h, (46.31±2.12)h, (6.32±2.11)ind. and (0.0431±0.0126)/h with the rise of...
|
PDF Full Text Request