50%杀螺胺乙醇胺盐可湿性粉剂浸杀法冬季对土表及土层下钉螺杀灭效果

目的　评价在冬季使用50%杀螺胺乙醇胺盐可湿性粉剂（WPNES）浸杀法对土表以及不同土层深度钉螺的杀灭效果。方法　在冬季室外低温环境下，将钉螺放置在土层表面以及土层下2、5 cm和10 cm，使用2 mg/L和1 mg/L 50% WPNES药液分别浸泡1、3、7 d，以脱氯自来水作为对照，观察土表及土层内钉螺死亡情况。结果　在冬季采用2 mg/L和1 mg/L 50% WPNES浸杀法施药，施药3 d后土表钉螺校正死亡率分别为98.0%和76.0%，7 d后钉螺死亡率均为100.0%。在冬季采用2 mg/L和1 mg/L 50% WPNES浸杀法施药7 d后，土层下2 cm钉螺校正死亡率分别为达95.5%和85.6%，土层下5 cm钉螺校正死亡率分别为66.0%和6.4%。2 mg/L和1 mg/L 50% WPNES施药7 d后，土层下10 cm钉螺死亡率与对照组相比，差异无统计学意义（P均> 0.05）。结论　冬季采用2 mg/L 50% WPNES浸杀7 d，对土表以及土层下5 cm以内的钉螺具有较好杀灭作用。

Molluscicidal effect of immersion with 50% wettable powder of niclosamide ethanolamine salt against Oncomelania hupensis on the soil surface and inside the soil layer in winter

Objective　To evaluate the molluscicidal effect of 50% wettable powder of niclosamide ethanolamine salt (WPNES) against Oncomelania hupensis on the soil surface and inside the soil layer by immersion method in winter. Methods　O. hupensis snails were placed on the soil surface and 2, 5 cm and 10 cm under the soil layer outdoors in winter, and then immersed in 50% WPNES at concentrations of 1 mg/L and 2 mg/L for 1, 3 d and 7 d, while dechlorinated water served as controls. Snail mortality was observed following immersion with 50% WPNES on the soil surface and inside the soil layer. Results　Following immersion with 50% WPNES at concentrations of 2 mg/L and 1 mg/L outdoors in winter, the 3-day corrected snail mortality rates were 98.0% and 76.0% on the soil surface, and the 7-day corrected snail mortality rate was both 100.0%. Following immersion with 50% WPNES at concentrations of 2 mg/L and 1 mg/L outdoors in winter, the 7-day corrected snail mortality rates were 95.5% and 85.6% 2 cm below the soil layer, 66.0% and 6.4% 5 cm below the soil layer. However, the 7-day snail mortality rate swere comparable between the 50% WPNES treatment group (at 2 mg/L and 1 mg/L) and controls 10 cm below the soil layer (both P > 0.05). Conclusion　Immersion of 50% WPNES at a concentration of 2 mg/L for 7 days presents a high molluscicidal efficacy against O. hupensis on the soil surface and 5 cm within the soil layers in winter.