Studies On The Effects Of Atrazine And Chlorpyrifos On Chinese Mitten-handed Crab, Eriocheir Sinensis

Pesticides are used judiciously to control a wide variety of agricultural pests and most of them pool ultimately into aquatic ecosystems throughout various pathways. Now there is a growing concern worldwide over the toxicity towards non-targeted organisms.However, the toxicity of pesticide to the Chinese mitten-handed crab, E. sinensis, which is economically important crustacean, has not been fully evaluated. Hence, an attempt was made to study the toxic effect of atrazine, a herbicide and chlorpyrifos, an organophosphate insecticide on crab at various developmental stages, including the acute toxic effects on embryo, juvenile and adult; effects of metabolism enzymes and antioxidant enzymes in embryos; effects of energy metabolism and growth in juveniles; effects of gonad mature in female adults. The purpose is to accumulate basal information for aquatic toxicology, and provide reference for criterion of water quality.The acute toxicity tests of herbicides atrazine and insecticides chlorpyrifos to Chinese mitten-handed crab E. sinensis were determined with the semi-static test. The Results of test found no effects on survival of juveniles I, juveniles II, adults crab exposed to atrazine, which indicate that atrazine has slight or no acute toxicity to E.sinensis. The calculated LC50 of 96h for chlorpyrifos to juveniles I, juveniles II, adults and embryos were 22.9, 75.9, 142.2 and 54.7 μg/L, respectively. 96-hr exposure of embryos caused a significant decreased in hatching time compared to controls at 10 and 20mg/L atrazine. However, 6.3 and 12.5μg/L chlorpyrifos treated embryos had a significantly increased hatching time. Based the results of embryos test, the safe concentrations of atrazine and chlorpyrifos are 100 and 0.06μg/L, respectively.The activities of superoxide dismutase (SOD), catalase (CAT), glutathion-S-transferases (GST) and acetylcholinesterase (AChE) were determined in Eriocheir sinensis during embryonic development. The elevated activities of antioxidant enzymes SOD and CAT indicated increased need to detoxify superoxide anion radical and to metabolize hydrogen peroxide. The increased activities of GSTindicated elevated detoxified function. The increased activities of AChE suggested that significant nervous system development is underway.The biochemical stress responses of atrazine and chlorpyrifos were studied in embryos and juvenile of E.sinensis. The antioxidant enzymes activities indicated that the embryos maybe suffered oxidant stress during exposed to atrazine and chlorpyrifos. The results suggested atrazine did not influenced the toxicokinetics of chlorpyrifos (resulting in increased formation of the o-analog), which suggested that direct conjugation to GSH without activation by phase I enzymes may be one main pathway of atrazine detoxication. The GST activities in hepatopancreas might be a promising biomarker of atrazine and chlorpyrifos long-period exposure, and AchE was a specially biomarker of the chlorpyrifos exposure.In the present investigation, laboratory experiment was conduced to study the toxicity of atazine and chlorpyrifos on oxygen-consumption and ammonia-N excretion of E. sinensis juvenile. The results indicated that atrazine exposure caused more catabolism to supply energy for overcome stress while chlorpyrifos exposure decreased the metabolism rate in juvenile crab.In present study, semistatic bioassay was employed to determine the toxicity of atrazine and chlorpyrifos on growth and body composition of E.sinensis juveniles. The results suggested that atrazine and chlorpyrifos decreased the accumulation of energy precursors and inhibited the growth of juvenile through delaying the molting.Using the RT-PCR techniques, the expression of mRNA encoding the Vg were observed in vitellogenic female ovaries and hepatopancreas, while was not detected in any other tissue including muscle, heart, and subepidermal tissue. The positive immunocytological staining with antibody against vitellin have been founded in ovaries and hepatopancreas of vitellogenic female, which is determined by imm...