氯硝柳胺泥敷灭螺土壤残留药物对钉螺和鱼类的毒性

目的观察氯硝柳胺泥敷灭螺后土壤残留药物的持续灭螺效果和对鱼类的毒性。方法选择3个试验点开展氯硝柳胺泥敷灭螺,设0、4、6、8、10g/m^2剂量,灭螺后7、15、30、90、180d将试验药泥取回实验室,配制成各种浓度的溶液,放入活螺和活鱼;现场将水引入试验沟渠,各组筑坝隔离,投放活螺和活鱼。观察室内和现场试验钉螺和鱼的死亡情况。结果残留药物灭螺试验,泥敷15d时室内和现场试验平均钉螺死亡率分别为29.64%和60.00%,30d时室内试验平均钉螺死亡率16.07%,钉螺死亡率随时间增加而降低（χ^2=207.578,P〈0.05）。残留药物鱼毒试验,泥敷15d时室内和现场试验鱼死亡率分别为5.83%和14.17%,表明钉螺死亡率高于鱼类。结论氯硝柳胺泥敷灭螺1月内环境残留药物仍具有一定的灭螺作用;泥敷灭螺15d后环境残留药物对鱼类的毒性已明显减小。

Toxicity of molluscicide residue in soil to snail and fish after soil pasting mixed with niclosamide

Objective To evaluate the persistent effect of killing Oncomelania snails and toxicity to fish after soil pasting mixed with niclosamide. Methods Three sites were selected in Sichuan Province. Soil pasting mixed with niclosamide was used in this study, and the dosages were 0, 4, 6, 8, and 10 g/m^2. The molluscicide soil was fetched to the lab 7, 15, 30, 90, 180 days after soil pasting. Serial solutions were made from the molluscicide soil, and the snails and fish were put into the solutions. At the same time the water was led into the experimental ditches and the dams were built between the different dosage groups, and the snails and fishes were put into the water in the ditch. The survival of the snails and fish was recorded in the lab and field within 7 days. Results The average mortality rates of snails were 29.64% and 60.00% in the lab and field 15 days after soil pasting, and 16.07 % in lab 30 days after soil pasting respectively. The mortality of snails decreased with the increasing of time （Х^2= 207. 578, P〈0.05）. The average mortality rates of fish were 5.83% and 14. 17% respectively in the lab and field 15 days after soil pasting. At the same time and dosage, the mortality of snails was much higher than that of fish. Conclusions The molluscicide residue could kill snail partially 1 month after soil pasting, and the toxicity of molluscicide residue to fish reduces significantly 15 days after soil pasting mixed with niclosamide.