Objective: To establish a snail control approach for spraying chemicals with drones against Oncomelania hupensis in complex snail habitats in hilly regions, and to evaluate its molluscicidal effect.
Methods: The protocol for evaluating the activity of spraying chemical molluscicides with drones against O. hupensis snails was formulated based on expert consultation and literature review. In August 2022, a pretest was conducted in a hillside field environment (12 000 m2) north of Dafengji Village, Dacang Township, Weishan County, Yunnan Province, which was assigned into four groups, of no less than 3 000 m2 in each group. In Group A, environmental cleaning was not conducted and 5% niclosamide ethanolamine salt granules were sprayed with drones at a dose of 40 g/m2, and in Group B, environmental cleaning was performed, followed by 5% niclosamide ethanolamine salt granules sprayed with drones at a dose of 40 g/m2, while in Group C, environmental cleaning was not conducted and 5% niclosamide ethanolamine salt granules were sprayed with knapsack sprayers at a dose of 40 g/m2, and in Group D, environmental cleaning was performed, followed by 5% niclosamide ethanolamine salt granules sprayed with knapsack sprayers at a dose of 40 g/m2. Then, each group was equally divided into six sections according to land area, with Section 1 for baseline surveys and sections 2 to 6 for snail surveys after chemical treatment. Snail surveys were conducted prior to chemical treatment and 1, 3, 5, 7 days post-treatment, and the mortality and corrected mortality of snails, density of living snails and costs of molluscicidal treatment were calculated in each group.
Results: The mortality and corrected mortality of snails were 69.49%, 69.09%, 53.57% and 83.48%, and 68.58%, 68.17%, 52.19% and 82.99% in groups A, B, C and D 14 days post-treatment, and the density of living snails reduced by 58.40%, 63.94%, 68.91% and 83.25% 14 days post-treatment relative to pre-treatment in four groups, respectively. The median concentrations of chemical molluscicides were 37.08, 35.42, 42.50 g/m2 and 56.25 g/m2 in groups A, B, C and D, and the gross costs of chemical treatment were 0.93, 1.50, 0.46 Yuan per m2 and 1.03 Yuan per m2 in groups A, B, C and D, respectively.
Conclusions: The molluscicidal effect of spraying 5% niclosamide ethanolamine salt granules with drones against O. hupensis snails is superior to manual chemical treatment without environmental cleaning, and chemical treatment with drones and manual chemical treatment show comparable molluscicidal effects following environmental cleaning in hilly regions. The cost of chemical treatment with drones is slightly higher than manual chemical treatment regardless of environmental cleaning. Spraying 5% niclosamide ethanolamine salt granules with drones is recommended in complex settings with difficulty in environmental cleaning to improve the molluscicidal activity and efficiency against O. hupensis snails.
［摘要］ 目的 探索建立山丘型地区复杂钉螺孳生环境中运用无人机喷撒灭螺药物的方法, 并评价其灭螺效果。方法 通过专家咨询及查阅文献制定无人机喷撒灭螺药物效果评价方案。2022 年 8 月, 选取云南省巍山县大仓镇大凤集自 然村以北的山坡田为预试验现场, 将预试验现场 (12 000 m2) 分为 4 组, 每组面积不少于 3 000 m2。A 组试验区域不清障, 采用无人机喷撒 5% 杀螺胺乙醇胺盐颗粒剂 (剂量 40 g/m2); B 组试验区域先进行清障, 然后采用无人机喷撒 5% 杀螺胺乙 醇胺盐颗粒剂 (剂量 40 g/m2); C 组试验区域不清障, 采用背负式喷撒 (粉) 机喷撒5% 杀螺胺乙醇胺盐颗粒剂 (剂量40 g/m2); D组试验区域先清障, 然后采用背负式喷撒 (粉) 机喷撒 5% 杀螺胺乙醇胺盐颗粒剂 (剂量 40 g/m2)。将 4 组试验区 域再分别按面积均分为6个地块, 并依次编号为 1、2、3、4、5、6 区, 其中 1 区用于开展基线调查, 2~6 区用于灭螺后 1、3、5、7、14 d 钉螺调查。分别于施药前及施药后 1、3、5、7 d 和 14 d 开展钉螺调查, 计算各组钉螺死亡率、校正死亡率、活螺密度 以及灭螺成本。结果 施药后 14 d, A、B、C、D 组钉螺死亡率分别为 69.49%、69.09%、53.57% 和 83.48%, 校正死亡率分别 为 68.58%、68.17%、52.19%、82.99%, 活螺密度分别较施药前下降 58.40%、63.94%、68.91% 和 83.25%。A、B 组平均药物中 位浓度分别为 37.08 g/m2 和 35.42 g/m2, C、D 组平均药物中位浓度分别为 42.50 g/m2 和 56.25 g/m2; A、B 组灭螺 1 m2 的总成 本分别为 0.93、1.50 元; C、D 组灭螺 1 m2 的总成本分别为 0.46、1.03 元。结论 在环境未清障情况下, 山丘型地区无人机 喷撒 5% 杀螺胺乙醇胺盐颗粒剂灭螺效果优于人工施药; 在环境清障情况下, 无人机施药和人工施药灭螺效果相当; 无论 是否清障, 无人机施药灭螺成本均略高于人工施药。在难以开展人工清障灭螺的山丘型地区复杂环境, 可尝试采用无人 机喷撒 5% 杀螺胺乙醇胺盐颗粒剂灭螺, 以提高灭螺效果和效率。.
Keywords:
5% niclosamide ethanolamine salt granules; Drone; Hilly region; Molluscicidal effect;