Studies About Toxic Effects Of Carbaryl And Isoprocarb On Rotifer Brachionus Calyciflorus

As we know, environmental problem is still the major problem facing the world today, especially for the water pollution. Among them, water pollution caused by pesticide residue is to be solved as soon as possible. In this paper, I researched the influence of pesticides(carbaryl and soprocarb) on the growth and reproduction of Brachionus calyciflorus, under certain conditions, using the ecological toxicology methods.The main contents and results were as follows:1. The acute effect and chronic toxicity of carbaryl on the life cycle in the rotifer Brachionus calyciflorus were studied, using single individual life table method, under laboratory conditions at(25±1)?. The results showed that the 24 h LC50 value of carbaryl on Brachionus calyciflorus was 4.868 mg·L-1, and exhibited a probit model equation: Probit(P)=6.465X-4.444, 95% confidence interval was 4.538~5.229 mg·L-1. The results of chronic toxicity experiment showed that carbaryl had a significant impact on main developmental stage, average life span, net reproduction rate, innate rate of increase and generation time except the spawning. Compared with the control group, carbaryl significantly reduced the average life span, net reproduction rate and innate rate of increase, and the effect of the high concentration of carbaryl on the average life span and innate rate of increase was even more remarkable. Larval stage length and embryonic development time extended with the increase of carbaryl concentration. Except the concentration of 2.2 mg·L-1, other concentrations of carbaryl significantly shortened the generation time of the rotifer. The generation time and net reproduction rate of the rotifer had a significant curve-correlation to concentration of carbaryl(R2=0.920, P<0.05; R2=0.945, P<0.05).2. Under the different concentrations(1.0×106 cells·mL-1, 3.0×106 cells·mL-1 and 6.0×106 cells·mL-1)of Chlorella vulgaris, the influence of carbaryl on three-day parameters of population growth,five-day resting egg production and twenty-day resting egg hatchability in the rotifer Brachionus calyciflorus were sdudied via community culture method. The results showed that the experimental groups were not established when the concentration of Chlorella vulgaris was 1.0×106 cells·mL-1, and should be abandoned. When the concentration of Chlorella vulgaris was 3.0×106 cells·mL-1, the influence of carbaryl on OF/NOF, FR, RE, r and the resting egg hatchability were significant, excepting on nitrogen fixation rate. Among them, the influence on FR and RE were the most significant.Significant affect was showed when pesticide concentration was very low. When the concentration of Chlorella vulgaris was 6.0×106 cells·mL-1, the influence of carbaryl on the various population growth parameters, RE and the resting egg hatchability were significant and when pesticide concentration increased, then the influence were more significant.In addition, we could see that,within a certain range, rotifers' drug resistance increased along with the rising of the concentrations of food.3. The acute effect and chronic toxicity of different concentrations(0.25, 0.5, 0.75, 1.0, 1.25 and 1.5 mg·L-1)of isoprocarb on the life cycle in the rotifer B. calyciflorus were studied, using single individual life table method, under laboratory conditions at(25±1)?. It showed that the 24 h LC50 value of isoprocarb on B. alyciflorus was 1.542 mg·L-1, 95% confidence interval was 1.381~1.720 mg·L-1, and exhibited a probit model equation:Probit(P)=-0.849+4.511. In the same way, the 96 h LC50 value was 1.367 mg·L-1, 95% confidence interval was 0.980~1.827 mg·L-1, and the safe concentration was 0.1367 mg·L-1. The results of chronic toxicity experiment showed that isoprocarb had a appreciable impact on main developmental stage, average life span, net reproduction rate, life expectation, innate rate of increase and generation time. Compared with the control group, isoprocarb extended larval stage length and embryonic development time of rotifers and shortened reproductive and average life span of rotifers in different degrees. With the increase of concentration of isoprocarb, net reproduction rate, life expectation, innate rate of increase and generation time of B. calyciflorus reduced(or shortened) significantly. And innate rate of increase reduced significantly even the concentration of isoprocarb was very low. Thus, we could see that innate rate of increase was the most sensitive indicator in this condition.4. Toxic effects of isoprocarb on the population growth parameters of B. calyciflorus were examined in laboratory using third-day population growth test. In the experimental concentration range, there was a significant linear correlation between the population growth rate and isoprocarb(R2=0.892,P<0.05);and population density of rotifers reduced with concentration of isopropyl elevated(R2=0.923,P<0.01). Toxic effects of isoprocarb on reproductions of B. calyciflorus were examined in laboratory using three-day population growth parameters(OF/NOF, MF/AF, RE, FR and r), five-day resting egg production and twenty-day resting egg hatchability. The results showed that all of the indicators had significant relationships with isoprocarb except females /non-ovigerous females and resting egg hatchability. The results also showed that there were no significant relationships between isoprocarb and offspring of B. calyciflorus.