Objective: To investigate the distribution of Oncomelania hupensis snails in different water systems in Anqing City from 2016 to 2022, so as to provide insights into snail control in the city.
Methods: Snail survey data and distribution of water systems in snail-infested environments were collected from schistosomiasis-endemic areas of Anqing City from 2016 to 2022. The vector maps of towns and water systems in Anqing City were downloaded from National Geomatics Center of China. The GPS toolbox APP version 2.7.9 was downloaded from a smartphone to record the longitude and latitude of each snail-infested environment in Anqing City, which were loaded into the software LocaSpace Viewer version 4.4.6 to map the distribution of snail-infested environments. The area of snail habitats, area of emerging snail habitats, area of re-emerging snail habitats, type of snail habitats and density of living snails were descriptively analyzed. The spatial database of snail-infested environments in Anqing City was built with the software ArcGIS version 10.8, and the density of living snails was subjected to spatial autocorrelation analysis in snail-infested environments. The hotspot clusters of density of living snails were identified in snail-infested environments and the density of living snails was subjected to standard deviation ellipse analysis in snail-infested environments.
Results: A total of 515 snail-infested environments were identified in water systems in Anqing City in 2022. The area of snail habitats reduced from 6 909.32 hm2 in 2016 to 6 087.48 hm2 in 2022, with a reduction of 11.89%, and the areas of snail habitats reduced by 2.39%, 21.71% and 1.67% in the main stream of the Yangtze River, the Wanhe River system and the Caizihu River system in Anhui City, respectively, while the area of snail habitats increased by 3.94% in the Huayang River system. Emerging or re-emerging snail habitats were identified in Anqing City each year during the period from 2016 to 2018 and from 2020 to 2020. The density of living snails appeared a tendency towards a decline in the Wanhe River system (b = -0.030, t = -3.019, P < 0.05) and Huayang River system (b = -0.029, t = -4.296, P < 0.05) in Anqing City from 2016 to 2022, and fluctuated in the main stream of the Yangtze River (b = 0.028, t = 1.019, P > 0.05) and the Caizihu River system (b = 0.020, t = 1.877, P > 0.05). A positive global spatial autocorrelation was identified in the density of living snails in Anqing City each year from 2016 to 2022 (all Moran's I values > 0, all P values < 0.05), and the hotspot clusters of density of living snails in snail-infested environments were mainly distributed in the Wanhe River system (Shankou Township, Hongpu Township, Yueshan Township and Wanghe Townshpi), the main stream system of the Yangtze River (Dalongshan Township, Wanhe Farm, Haikou Township and Huayang Township), the Huayang River system (Dashi Township and Xuqiao Township) and the Caizihu River system (Xiushan Township and Fangang Township). The ratio of the long to short axes of the standard deviation ellipse was 1.72 to 2.06 for the density of living snails in snail-infested environments in Anqing City from 2016 to 2022, and snails were mainly distributed in the southwest to northeast, and appeared the east-west and north-south spread.
Conclusions: The areas of snail habitats and the density of living snails appeared a tendency towards a decline in different water systems in Anqing City from 2016 to 2022; however, there is still a risk of snail spread. Reinforced surveillance and precision control of snails are required in Anqing City.
［摘要］ 目的 分析2016—2022年安庆市不同水系钉螺分布, 为该市钉螺控制提供参考。方法收集2016—2022年安 庆市血吸虫病流行区钉螺调查数据、有螺环境水系分布数据。于国家基础地理信息中心下载安庆市乡 (镇) 和水系矢量 地图; 通过智能手机下载GPS工具箱APP 2.7.9, 记录安庆市各有螺环境经纬度, 导入图新地球软件4.4.6, 绘制有螺环境 面数据。对不同水系有螺面积、新发现有螺面积、复现有螺面积、环境类型、活螺密度等指标进行描述性分析。采用Arc-GIS 10.8软件建立安庆市有螺环境空间数据库, 对有螺环境活螺密度进行空间自相关分析, 探索有螺环境活螺密度热点 聚集区, 对有螺环境活螺密度进行标准差椭圆分析。结果2022年安庆市各水系累计发现有螺环境515处。2016— 2022年, 全市有螺面积从6 909.32 hm2降至6 087.48 hm2, 下降幅度为11.89%; 其中该市长江干流、皖河水系和菜子湖水 系有螺面积分别下降2.39%、21.71%和1.67%; 华阳河水系有螺面积上升3.94%。2016—2018年与2020—2022年, 安庆 市各年份均有新发现或复现有螺环境。2016—2022年, 安庆市皖河水系 (b = -0.030, t = -3.019, P < 0.05) 和华阳河水 系 (b = -0.029, t = -4.296, P < 0.05) 活螺密度呈下降趋势; 长江干流 (b = 0.028, t = 1.019, P > 0.05) 与菜子湖 (b = 0.020, t = 1.877, P > 0.05) 水系活螺密度呈波动状态。2016—2022年, 安庆市各年份活螺密度存在全局空间正相关 (Moran's I 指 数均> 0, P 均< 0.05), 有螺环境活螺密度热点聚集区主要分布于皖河水系 (山口乡、洪铺镇、月山镇和王河镇) 、长江干流 水系 (大龙山镇、皖河农场、海口镇和华阳镇) 、华阳河水系 (大石乡和徐桥镇) 和菜子湖水系 (秀山乡和范岗镇) 。2016— 2022年, 安庆市有螺环境活螺密度标准差椭圆长轴与短轴比例为1.72 ~ 2.06, 钉螺分布存在一定方向性, 主要为西南-东 北方向, 并在东西和南北方向均存在扩散。结论2016—2022年安庆市部分水系有螺面积和活螺密度呈下降趋势, 但 仍存在钉螺扩散风险, 需加强螺情监测和精准控制。.
Keywords:
Anqing City;