湖沼型疫区沟渠反复药物灭钉螺效果观察

Effects of repeated application of molluscicide in the control of snails in the marshland and lake region

目的观察湖沼型疫区沟渠反复药物灭钉螺效果,为制定防治对策提供科学依据。方法选择有感染性钉螺分布的灌渠1条,采用50%氯硝柳胺乙醇胺盐可湿性粉剂2g/m2喷洒法反复实施药物灭螺,每次药物灭螺后采用系统抽样方法进行近期(14d)和远期(30～90d)效果现场考核,观察钉螺死亡率、螺口密度和感染性钉螺变化情况。结果 4次药物灭螺,近期效果考核钉螺死亡率在87.35%～90.48%之间,校正死亡率分别87.29%、84.69%、88.74%、88.47%,与灭前比较,差异有统计学意义(χ2=302.14、430.00、241.83、61.07,P均<0.01);活螺平均密度下降率分别为94.35%、85.48%、91.94%、94.35%;未发现感染性钉螺。3次远期效果考核钉螺死亡率在4.76%～23.33%之间,与灭前比较无差异;活螺平均密度下降率分别为35.48%、29.84%、50.87%;后2次未发现感染性钉螺。结论反复药物灭螺对控制感染性钉螺作用明显,但对年度钉螺螺口消长作用有限。

Objective To evaluate the effect of repeated application of molluscicide in the control of snails in the lake region. Methods One of the irrigation channel was selected in this study.Between May and November,50% of niclosamide ethanolamine salt （WP 2 g/m2） was repeatedly sprayed over the irrigation channel. Samples were collected 14 days and 30 to 90 days after the drug application.The death rate, screw density and the degree of infection were determined. Results After 4 times of drug application, the snail mortality rate was between 87.35% and 90.48%. The corrected mortality rates were 87.29%, 84.69%, 88.74%, 88.47%, and the difference was statistically significant （χ2= 302.14,430.00,241.83,61.07,P〈0.01）. The reduction of average density of living snails in these 4 drug applications was 94.35%, 85.48%, 91.94%, and 94.35%, respectively. Infectiou snails were not found. The mortality after 30-90 days of drug application was ranged from 4.76% to 23.3%, and the values were similar to the pre-drug treatment. The average density of living snails these 3 applications were 35.48%, 29.84%, and 50.87%, respectively. Found no infected snails in the last two times. Conclusion Repeated application of molluscicide is an effective method to control the growth of snail.