吡螺脲硫酸盐可湿性粉剂在湖沼型血吸虫病流行区的灭螺效果评价

Evaluation on molluscicidal effect of wettable powder of pyriclobenzuron sulphate in marshland schistosomiasis endemic areas

目的评价吡螺豚硫酸盐可湿性粉剂(WPPS)在湖沼型血吸虫病流行区的灭螺效果及其对鱼类的毒性,为该药在湖沼型血吸虫病流行区的推广应用提供科学依据。方法于鄱阳湖洲滩选取6块区域进行除障,计算钉螺自然死亡率。兑配25%W PPS溶于水中使最终浓度分别为1、2、4、8 g/m^3,兑配杀螺胺乙醇胺盐(WPNES)溶于水中使最终浓度为1 g/m^3,均匀喷洒施药,空白对照组施用清水,于施药后1、3、7 d,系统抽样法进行钉螺调査,压碎法鉴別钉螺死活,并记录处理螺数、死螺数。将湖北省垸内环境筑坝分隔成6段试验区,每段投放鲫鱼30条,并适应性饲养I d。其中4段药物试验组施用2.5、5.0、7.5 g/m^3 WPPS,药物对照组施用2g/m^3 WPNE S,空白对照组施用清水,分别于施药后的1、2、3 d记录鲫鱼存活率。结果喷洒灭螺药物后1 d和3 d,5个施药组钉螺校正死亡率均超过85%以上,1 g/m^3 WPPS和2 g/m^3 WPPS处理下,3 d的死亡率(93.1%和95.0%)高于1 d的死亡率(88.2%和90.9%)。现场灭螺7 d后,1、2、4、8 g/m^3 WPPS处理下的钉螺校正死亡率分别为90.4%、90.0%、90.3%、89.8%,均高于1 g/m^3 WPNES处理后的钉螺校正死亡率(76.0%)(P<0.05)。2 g/m^3 WPPS处理1、3、7 d后的钉螺校正死亡率均高于90%,于第3天达到最大值(94.7%)。鱼毒性试验结果显示,2.5和5.0 g/m^3 WPPS施药后1、2、3 d的鲫鱼死亡率接近空白对照组(0、3.3%和6.9%),差异无统计学意义(尸>0.05),7.5 g/m^3 WPPS施药后2 d和3 d的死亡率均为50.0%。2.5、5.0、7.5 g/m^3 WPPS处理下的鲫鱼死亡率差异有统计学意义(P<0.05)。结论WPPS可有效杀灭钉螺且对鱼类生物安全性较高,可应用于洲滩以及鱼塘、虾塘等垸内环境。该药对湖沼型血吸虫病流行区灭螺药物的选择具有一定参考价值。

Objective To evaluate the molluscicidal effect of wettable powder of pyriclobenzuron sulphate(WPPS)and its toxicity to fish in marshland schistosomiasis epidemic areas,so as to provide scientific evidence for the extensive application of this molluscicide in marshland schistosomiasis epidemic areas.Methods Six pilot sites in the marshland around Poyang Lake were selected and all obstacles within these sites were removed.The natural mortality of Oncomelania was calculated.The 25%wettable powder of pyriclobenzuron sulphate(WPPS)was dissolved in water to a final concentration of 1,2,4,8 g/m^3.The commonly used molluscicidal drug niclosamide ethanolamine salt(WPNES)was dissolved in water to a final concentration of 1 g/m^3.Then these formulated molluscicidal drugs in different concentration were sprayed on the different spots of marshland evenly.The control spot was sprayed with water only.The Oncomelania were collected and examined for their viability by crushing the snails 1,3 and 7 days after administration of the drugs.To test the toxicity of the molluscicidal drugs to fish,a water area in Hubei Province was selected and separated into 6 chambers.Total 30 carp fishes were put into each chamber and adapt for 1 day before administration with WPPS to the final concentration of 2.5,5.0 and 7.5 g/m^3.The control chamber was administrated with WPNES to 2 g/m^3.The blank control chamber was added with clean water only.The survival rate of carp was counted and recorded after administration with the drugs for consecutive three days.Results The adjusted mortality of Oncomelania in each group was more than 85%after administration with molluscicidal drugs for 1 and 3 days.The mortality of Oncomelania 3 days after administration with 1 g/m^3,2 g/m^3 WPPS(93.1%,95.0%)was higher than that with drugs for 1 day(88.2%,90.9%).The adjusted mortality of Oncomelania after administration with 4 different concentrations of WPPS(1,2,4,8 g/m^3)were 90.4%,90.0%,90.3%and 89.8%,respectively,all higher than that using 1 g/m2 WPNES(76.0%)with significant difference(P<0.05).The adjusted mortality of Oncomelania was higher than 90%at 1 day,3 days and 7 days when 2 g/m^2 WPPS was administrated with highest of 94.7%at 3 days.The fish toxicity test results showed that the mortality of carp at 2.5 g/m^3,5.0 g/m^3 of WPPS was similar to that of the blank control(0,3.3%,6.9%).The mortality of carp was 50%when WPPS was added to 7.5 g/m^3 for 2 and 3 days.Chi-square analysis of mortality of carp at 2.5,5.0,7.5 g/m^3 WPPS was significantly different(P<0.05).Conclusion WPPS can effectively kill Oncomelania and has high biological safety for fish,so it can be applied in the environment of marshland,fish pond to effectively control Oncomelania,providing an effective alternative molluscicides in marshland schistosomiasis epidemic areas.