Objective: To evaluate the molluscicidal effect and cost of spraying molluscicides with drones against Oncomelania hupensis snails in marshland and lake areas, so as to provide new insights into field snail control in China.
Methods: A marshland and lake setting measuring approximately 12 000 m2 was selected in Wanzhi District, Wuhu City on June 2023 as the test field, and assigned to four groups, of 3 000 m2 in each group. Environmental cleaning was not conducted in groups A or B, which were given 5% niclosamide ethanolamine salt granules sprayed with knapsack-type sprayers and drones at a dose of 40 g/m2, and environmental cleaning was conducted in groups C and D, which were given 5% niclosamide ethanolamine salt granules sprayed with drones and knapsack-type sprayers at a dose of 40 g/m2, respectively. O. hupensis snails were surveyed before chemical treatment and 1, 3, 5, 7, 14 days post-treatment. The uniformity of chemicals was determined on the day of treatment, and the snail mortality, corrected snail mortality and density of living snails were calculated and compared among groups. The cost of molluscicides, labor fees of environmental cleaning and chemical treatment and cost of equipment were calculated, and the cost for a 1% reduction in the mean density of living snails was calculated 14 days post-treatment.
Results: The mean densities of living snails and mortality rates of snails were 1.82 to 2.85 snails/0.1 m2 and 1.41% to 2.94% in groups A, B, C and D before chemical treatment, and the mortality and corrected mortality of snails were 55.75%, 49.32%, 85.94% and 87.50%, and 55.00%, 48.47%, 85.70% and 87.29% in groups A, B, C and D 14 days post-treatment. There was a significant difference in the mortality of snails among the four groups 14 days post-treatment (χ2 = 38.735, P < 0.005), and there was a higher snail mortality in Group D than in Group A (χ2 = 16.876, P < 0.005), and higher in Group C than in Group B (χ2 = 20.508, P < 0.005). The density of living snails reduced by 55.00%, 43.94%, 90.43% and 87.14% 14 days post-treatment relative to pre-treatment in groups A, B, C and D, respectively. The test for uniformity of chemicals showed that the mean dose of molluscicides were 57.34, 55.21, 40.19 g/m2 and 32.37 g/m2 in groups A, B, C and D, respectively, and the minimal standard deviation (7.07) and coefficient of variation (0.18) of mean doses were seen in Group C. The costs for chemical treatment were 0.33 Yuan in groups A and B and 1.53 Yuan in groups C and D, respectively. The costs for a 1% reduction in the mean density of living snails were 17.82, 22.47, 50.73 Yuan and 52.56 Yuan in groups A, B, C, and D 14 days post-treatment, respectively.
Conclusions: The molluscicidal effect and cost of spraying 5% niclosamide ethanolamine salt granules with drones are comparable to manual spraying, and chemical treatment with drones are high in uniformity of molluscicides, time- and labor-saving, and feasible for applications in complex environments, which deserves widespread applications in the field of snail control.
［摘要］ 目的 评价湖沼型环境采用无人机喷撒灭螺药物的灭螺效果, 并对其成本进行分析, 为我国开展现场灭螺提供 新思路。方法 2023 年 6 月选择芜湖市湾沚区一块面积约 12 000 m2 的湖沼型环境作为试验现场, 将现场分成A、B、C、D 4个试验组, 每组面积约 3 000 m2; A、B 两组均不清障, 分别采用背负式喷雾喷粉机和无人机喷撒 5% 杀螺胺乙醇胺盐颗 粒剂 (40 g/m2); C、D 两组清障后分别采用无人机和背负式喷雾喷粉机喷撒 5% 杀螺胺乙醇胺盐颗粒剂 (40 g/m2)。分别于 施药前和施药后 1、3、5、7 d 和 14 d 对各组进行钉螺调查, 并于施药当天测定各组药物均匀度, 计算并比较各组钉螺死亡 率、校正死亡率、活螺密度。统计各组灭螺药物成本、清障及施药人工费、设备费, 计算施药后 14 d 各组活螺平均密度每 下降 1% 的成本。结果 施药前, A、B、C、D 4 组活螺平均密度在 1.82 ~ 2.85 只/0.1 m2, 钉螺死亡率在1.41% ~ 2.94%。施 药后14 d, A、B、C、D组钉螺死亡率分别为55.74%、49.32%、85.94%、87.50%, 校正钉螺死亡率分别为55.00%、48.47%、85.70%、87.29%; 4组钉螺死亡率差异有统计学意义 (χ2 = 38.735, P < 0.005), 其中 D 组钉螺死亡率高于A组 (χ2 = 16.876, P < 0.005), C组钉螺死亡率高于B组 (χ2 = 20.508, P < 0.005)。施药后 14 d, 各组活螺密度较施药前分别下降了 55.00%、43.94%、90.43%、87.14%。药物均匀度测试结果表明, A、B、C、D组喷撒药物平均剂量分别为 57.34、55.21、40.19、32.37 g/m2, C组平均剂量标准差 (7.07) 及变异系数 (0.18) 均最小。A、B组1 m2 灭螺成本均为0.33元, C、D 组均为 1.53 元。施药后 14 d, A、B、C、D组活螺平均密度每下降1%的成本分别为 17.82、22.47、50.73、52.56元/m2。结论 无人机喷撒灭螺药物 的灭螺效果及成本均与人工施药相当, 且药物喷洒均匀度高、省时省力, 能应用于复杂环境, 可在灭螺现场推广使用。.
Keywords:
5% niclosamide ethanolamine salt granule; Drone; Marshland and lake area; Molluscicidal effect;