Influence Of Four Kinds Of Strobilurin Fungicides On Zebrafish And Trichogramma

Strobilurin fungicides is a kind of low toxicity, broad-spectrum, highly efficient absorption of fungicides with the role of protection, treatment, eradication against the Ascomycetes, Deuteromycetes, Oomycetes and Basidiomycetes etc. Strobilurin fungicides also have a good effect on other pathogenic bacteria, which are resistant to other fungicides. With the increasing of strobilurin fungicides, the risks of strobilurin fungicides to the environment and non-target organisms are increasing. Trichogramma and zebra fish, the important representative of predators of insects and aquatic organisms, are the important indicator of environmental safety assessment for chemical pollutants. In this study, we dectected the effects of four strobilurin fungicides on Trichogramma and zebra fish, and revealed the toxicity mechanism, whichwouldprovide important information for establishing and improving the evaluation system, and guide the actual application of these fungicides. The main findings are as follows:(1) The acute toxicity of the four strobilurin fungicides to Trichogramma was detected by exposing Trichogramma adult to residues of pesticides on glass tubes. Results showed that picoxystrobin and pyraclostrobin have higher risks to Trichogramma compared with azoxystrobin and kresoxim-methyl. This study provides informative data for implementing both biological and chemical control strategies in integrated pest management.(2) With the semi-static method, the acute toxicity of four strobilurin fungicides to zebrafish was detected. The results showed that four kinds of strobilurin fungicides have high toxicity to zebrafish, and the descending order of toxicity of these four strobilurin fungicides is as follow, pyraclostrobin> picoxystrobin> kresoxim-methyl> azoxystrobin. The toxicity of different formulations of the same ingredient were different to zebrafish. Our results showed the toxicity of formulations of SC and EC were higher than that of original drug, but the toxicity of WG was slightly lower than that of original drug.(3) According to the standard of OECD, effects of four strobilurin fungicides to zebrafish embryos were detected. The results showed that four kinds of strobilurin fungicides have significant developmental toxicity to zebrafish embryos. After exposed in a certain concentration of four strobilurin fungicides, survival and hatching rates of zebrafish embryo showed a significant dose and timedependent relationship. Embryonic malformations were observed, including pericardial cysts, yolk sac, protruding tail deformity, spine bending et al. When exposed at 72 h, the heart rate of juvenile zebrafish was maximum, the higher the concentration of exposure treatment group, the lower heart rate of juvenile fish, the more severe pericardial cyst.(4) The effect of four kind of fungicides(pyraclostrobin, picoxystrobin, kresoxim-methyl and azoxystrobin) on the activity of glutathione transferase(GST), carboxylesterase(CarE), catalase(CAT) and peroxidase(POD) was detected in juvenile zebrafish(96h). The results showed that the degree of oxidative stress of four kinds of strobilurin fungicides on the embryo is different, but all tested fungicides lead to the increasment of activities of carboxylesterase(CarE) and catalase(CAT). Under the stress of pyraclostrobin, the activity of glutathione transferase(GST) was suppressed, while the other three fungicides which were induced; After exposed to azoxystrobin and picoxystrobin, the activity of peroxidase(POD) was inhibited, but which was induced in the stress of pyraclostrobin and kresoxim-methyl.(5) The effect of four kind of fungicides(pyraclostrobin, picoxystrobin, kresoxim-methyl and azoxystrobin) on the activity of glutathione transferase(GST), carboxylesterase(CarE), catalase(CAT) and peroxidase(POD) superoxide dismutase(SOD) was detected in zebrafish liver. After exposed to pyraclostrobin and picoxystrobin, the severe oxidative stress injury in zebrafish was observed in the early time with a large amount of lipid peroxidation. The GST activity was induced, while that of SOD, CAT and POD was inhibited. Lipid peroxidation stress induced by kresoxim-methyl and azoxystrobin was light in zebrafish, but the stress could accumulate excess reactive oxygen species with prolonging the exposure time which lead to lipid peroxidation injury in zebrafish. With the prolongation of exposure time, the treatment zebrafish gradually adapt to the continuous oxidative stress induced by the tested four fungicides. Under the stress of pyraclostrobin, picoxystrobin and azoxystrobin, the capacity of antioxidant and endurance of females were higher than males; But instead, under the stress of kresoxim-methyl.