Hong-Chu Wu, Yu-Cai Ma, Zheng-Qiu Zhang, Kai Tang, Guang-Ling Du, Jin Zhang, Jian Wang, Dao-Jian Zhu, Yin-Ping Zuo
Key Laboratory of National Health Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasite and Vector Control Technology, Jiangsu Institute of Parasitic Diseases, Wuxi 214064, China.
Hanjiang District Center for Disease Control and Prevention, Yangzhou City, Jiangsu Province, China.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi. 2018 Sep 11;30(6):619-624. doi: 10.16250/j.32.1374.2018222.
To evaluate the effect and cost-effectiveness of three commonly used molluscicides, 4% "Luo-wei" (tea-seed distilled saponins, TDS), 50% niclosamide ethanolamine salt wettable powder (NESWP), and 26% metaldehyde and niclosamide suspension concentrate (MNSC) in large-scale field application, so as to provide the references for formulating the strategy of snail control.
The field test and parallel comparison were implemented. A marshland with snails of the Yangtze River was divided into 4 parts (10 hm) for the research, and three of them were experimental areas while the last one was a blank control area. The experimental areas were sprayed with 4% "Luo-wei", 50% NESWP and 26% MNSC respectively for 3 times and the interval was 1 week. Seven days after each spraying the effect of snail control was investigated, and the costs of molluscicides, labor, transportation, fuel consumption and mechanical loss were recorded. The cost of each molluscicide, snail mortality, snail density, and the cost of increasing 1% of snail mortality per 100 m were analyzed and compared.
After the first, second and third spraying, the corrected snail mortality rates were 67.34%, 76.55% and 84.60% respectively in the 4% "Luo-wei" group; the corrected snail mortality rates were 64.71%, 75.17% and 83.89% respectively in the 50% NESWP group; the corrected snail mortality rates were 66.55%, 76.27% and 86.67% respectively in the 26% MNSC group. There was no significant difference among the 3 groups in the snail mortality at the same spraying time (χ = 1.590, 0.571, 3.238, all 0.05) . In addition, along with the increase of the spraying times, the snail mortality of each group was increased significantly compared to that of the control group (χ = 79.333, 94.718, 117.020, all < 0.01) . After the first, second and third spraying, the reduction rates of snail density were 69.82%-86.60% in the 4% "Luo-wei" group, 68.66%-86.55% in the 50% NESWP group, and 71.89%-88.87% in the 26% MNSC group respectively. The decreasing amplitude of the snail density was more than 85% in all the experimental areas after 3 rounds of spraying molluscicide. The snail control costs per 100 hm were 19.57, 11.97 Yuan and 10.47 Yuan in the 4% "Luo-wei" group, 50% NESWP group, and 26% MNSC group respectively. After the first, second and third spraying, the costs of increasing 1% of snail mortality per 100 m were 0.30, 2.08 Yuan and 2.38 Yuan in the 4% "Luo-wei" group, 0.20, 1.10 Yuan and 1.32 Yuan in the 50% NESWP group, and 0.17, 1.04 Yuan and 0.97 Yuan in the 26% MNSC group respectively, and the cost-effectiveness was the highest at the first spraying in all the three groups.
The effects of the three molluscicides for snail control are similar, but the efficacy of snail control is reduced as the spraying time increases.
评价4%“螺威”（茶籽饼蒸馏皂甙，TDS）、50%氯硝柳胺乙醇胺盐可湿性粉剂（NESWP）和26% 密达（杀螺胺乙醇胺盐悬浮剂，MNSC）3种常用灭螺剂在大规模现场应用中的效果及成本效益，为制定灭螺策略提供参考。
进行现场试验和平行对照。将一片有长江钉螺的沼泽地划分为4个部分（10 hm²）进行研究，其中3个为试验区，另1个为空白对照区。试验区分别用4%“螺威”、50% NESWP和26% MNSC各喷洒3次，间隔1周。每次喷洒后7天调查灭螺效果，并记录灭螺剂、人工、运输、燃油消耗及机械损耗等成本。分析比较各灭螺剂的成本、钉螺死亡率、钉螺密度及每增加1%钉螺死亡率每100 m²的成本。
4%“螺威”组第1、2、3次喷洒后校正钉螺死亡率分别为67.34%、76.55%和84.60%；50% NESWP组校正钉螺死亡率分别为64.71%、75.17%和83.89%；26% MNSC组校正钉螺死亡率分别为66.55%、76.27%和86.67%。3组在同一喷洒时间的钉螺死亡率差异无统计学意义（χ²=1.590、0.571、3.238，均P>0.05）。此外，随着喷洒次数增加，各组钉螺死亡率与对照组相比均显著升高（χ²=79.333、94.718、117.020，均P<0.01）。4%“螺威”组第1、2、3次喷洒后钉螺密度降低率分别为69.82% - 86.60%，50% NESWP组为68.66% - 86.55%，26% MNSC组为71.89% - 88.87%。3轮喷洒灭螺剂后各试验区钉螺密度下降幅度均超过85%。4%“螺威”组、50% NESWP组和26% MNSC组每100 hm²的灭螺成本分别为19.57元、11.97元和10.47元。4%“螺威”组第1、2、3次喷洒后每增加1%钉螺死亡率每100 m²的成本分别为0.30元、2.08元和2.38元；50% NESWP组分别为0.20元、1.10元和1.32元；26% MNSC组分别为0.17元、1.04元和0.97元，3组均在第1次喷洒时成本效益最高。
3种灭螺剂的灭螺效果相似，但随着喷洒次数增加灭螺效果降低。
