The toxic effects of 0.32% azadirachtin EC on survival, growth and reproduction of water fleas Daphnia magna were studied by acute and chronic toxicity tests. The acute toxicity test showed that azadirachtin as a highly toxic substance had the 24 h LC50 of 39 μg/L, 48 h LC50 of 17 μg/L and the safety concentration of 1. 12 μg/L for the water fleas. The Chronic toxicity test revealed that the water fleas showed decrease in intrinsic rate of population increase (rm) , number of clutches per female, total offspring per female, generation time (T), net reproductive rate (R0) , and survival time with the increasing azadirachtin concentration. There was no significant difference in the rm in the water fleas between the control group and low concentration groups (0. 432, 0. 768 and 1. 120 μg/L) (P>0.05). The rm was decreased from 0. 347 6 d-1 at insecticide concentration of 1.340 to 0.306 3 d-1 at insecti cide concentration of 2.400 μg/L. The minimal number of clutches per female ( 2.47 times) and total offspring per female (26.87 ind. ) , the minimal survival time (13.60 d) , the minimal R0( 24. 696 1), and T(11.4399 d) were observed at the maximal concentration of 2.400 μg/L. In conclusion, the findings show that high concentrations of azadirachtin leads to short survival time, and T, and to reduce in Ro number of clutches per female and total offspring per female significantly.
azadirachtinDaphnia magnatoxicityintrinsic rate of population increasesurvivalreproduction
NETL
NSTL
维普
万方数据
