三种常用农药对环棱螺、圆田螺和河蚬的急性毒性研究

采用急性毒性试验方法,研究了3种常用农药毒死蜱、丁草胺和三唑酮对3种本地底栖生物环棱螺Bellamya quadrata、圆田螺Cipangopaludina cathayensis和河蚬Corbicula fluminea的毒性效应,同时测定了螺类不同大小个体对供试农药的敏感性。结果显示:毒死蜱、丁草胺和三唑酮对环棱螺的96 h-LC50值分别为4.32、3.62和15.2 mg/L,对圆田螺的96 h-LC50值分别为6.31、4.31和16.9 mg/L,对河蚬的96 h-LC50值分别为8.75、6.83和26.5 mg/L;毒死蜱和丁草胺对3种供试生物均为中等毒性,三唑酮属低毒。环棱螺幼螺对毒死蜱、丁草胺和三唑酮的敏感性分别比大螺高2.52、1.84和1.72倍,圆田螺幼螺对毒死蜱、丁草胺和三唑酮的敏感性分别比大螺高2.26、2.26和2.67倍。因此,在田间使用3种供试农药时需注意对供试底栖生物尤其是其幼体的保护。

Acute toxicity of three common pesticides to Bellamya quadrata, Cipangopaludina cathayensis and Corbicula fluminea

The toxic effects of three common pesticides (chlorpyrifos,butachlor and triadimefon) to benthos of three native species (Bellamya quadrata,Cipangopaludina cathayensis and Corbicula fluminea) were studied by acute toxicity tests,and the sensitivity of B.quadrata and C.cathayensis in different size to pesticides was measured.The results showed that the 96 h-LC₅₀ values of chlorpyrifos,butachlor and triadimefon to B.quadrata were 4.32,3.62 and 15.2 mg/L,respectively,and those to C.cathayensis were 6.31,4.31 and 16.9 mg/L,respectively,to C.fluminea were 8.75,6.83 and 26.5 mg/L,respectively.Chlorpyrifos and butachlor showed middle toxicity to the three species,and triadimefon showed low toxicity.The young snails of B.quadrata were 2.52,1.84 and 1.72 times more sensitive to chlorpyrifos,butachlor and triadimefon,respectively,than the large snails;and the young snails of C.cathayensis were 2.26,2.26 and 2.67 times more sensitive to the three pesticides than the large snails.The results suggested that we should pay attention to protecting the benthos especially the larvae when applying the three pesticides in the fields.