Abstract: Objective　To examine the impact of arid climates on distribution of Oncomelania hupensis snails in the Poyang Lake area, so as to provide insights into precision control of O. hupensis snails in the Poyang Lake area. Methods　O. hupensis snails⁃infested grass islands in Hukou County, Lianxi District and Lushan City in the northern Poyang Lake area, and Jinxian County, Nanchang County and Poyang County in the southern Poyang Lake area were selected as the study areas, and the occurrence of frames with living snails and the mean density of living snails were captured from snail surveys in the study areas in spring and autumn each year from 2006 to 2023. Five years 2007, 2011, 2013, 2019 and 2022 were selected as drought years, and the mean daily water levels were collected at the Xingzi hydrological station in the drought years, normal flow year (2012) and flood year (2020). The numbers of days with water levels ranging from the lower elevation (11 m) to the upper elevation (16 m) for snail survival and the numbers of days with water levels of 11 m and below were collected in the Poyang Lake area, and the changes of snail indicators were compared in different grass islands in the Poyang Lake area before and after drought. Results　The numbers of days with water levels ranging from 11 to 16 m were 110, 88, 136 d and 125 d at the Xingzi hydrological station in four drought years 2007, 2011, 2013 and 2019, which were less than in the flow year and flood year, and the days with water levels of 11 m and below were 242, 277, 220 d and 198 d in four drought years 2007, 2011, 2013 and 2019, which were longer than in the flow year and flood year. A total of 416 snails⁃infested marshlands were surveyed in the Poyang Lake area from 2006 to 2021, and the survey marshlands accounted for 43.12% (307/712) and 46.98% (109/232) of total marshlands in the southern and northern Poyang Lake areas, respectively. The median occurrence of frames with living snail and mean density of living snail were 0.60% (interquartile range, 4.04%) and 0.010 1 snail/0.1 m2 (interquartile range, 0.076 1 snail/0.1 m2) in drought years, which were both lower than those [1.33% (5.19%) and 0.022 8 (0.098 9) snail/0.1 m2] in non⁃drought years ([χ2] = 42.170 and 44.911, both P values < 0.01). The proportion of grass islands with a continuous decline in snail indicators was higher in the southern Poyang Lake area than in the northern Poyang Lake area after the next year of drought (24.24% vs. 2.33%; [χ2] = 10.633, P < 0.01), and the proportion of grass islands with rebounding snail indicators was higher in the northern Poyang Lake area than in the southern Poyang Lake area (53.49% vs. 15.76%; [χ2] = 26.966, P < 0.01). A longitudinal analysis of snail indicators in marshlands with rebounding snail indicators after drought showed 1 to 5 years for return to pre⁃drought snail status, with a median of 2 (interquartile range, 1) years, and snail status was more likely to rebound if the occurrence of frames with living snails and the mean density of living snails were 2.11% and 0.025 5 snail/0.1 m2 and greater in snails⁃infested grass islands. Conclusions　Drought causes a remarkable decline in O. hupensis snail indicators in the Poyang Lake area, with a more remarkable impact in the southern Poyang Lake area, and 1 to 5 years are required for return to pre⁃drought snail status.

Key words: Oncomelania hupensis, Schistosomiasis, Drought, Poyang Lake area

摘要： 目的　评价干旱气候对鄱阳湖区螺情的影响，为鄱阳湖区钉螺精准控制提供科学依据。方法 选择鄱阳湖区北部湖口县、濂溪区、庐山市和南部进贤县、南昌县、鄱阳县所属有螺草洲作为研究区域，收集2006—2023年研究区域每年春、秋两季开展钉螺调查获取的活螺框出现率和活螺平均密度。以2007、2011、2013、2019年和2022年5个年份为干旱年份，收集干旱年、2012年（平水年）、2020年（洪水年）星子水文站日均水位，分别统计上述各年份水位介于鄱阳湖区有螺环境下有螺线高程（11 m）和上有螺线高程（16 m）间的天数，以及水位≤ 11 m的天数，比较干旱前后鄱阳湖区不同区域螺情指标。结果 2007、2011、2013年和2019年4个干旱年星子水文站水位在11～16 m的天数分别为110、88、136 d和125 d，较平水年或洪水年少；水位≤ 11 m的天数分别为242、277、220 d和198 d，较平水年或洪水年多。2006—2021年累计调查鄱阳湖区416块有螺洲滩，其中鄱阳湖南、北部区域调查洲滩分别占南、北部洲滩总数的43.12%（307/712）和46.98%（109/232）。干旱年活螺框出现率与活螺平均密度中位数（四分位间距）[M（QR）]分别为0.60%（4.04%）和0.010 1（0.076 1）只/0.1 m2，低于非干旱年的1.33%（5.19%）和0.022 8（0.098 9）只/0.1 m2（[χ2] = 42.170、44.911，P均 < 0.01）。干旱次年后鄱阳湖南部区域螺情持续下降的草洲数比例高于北部区域（24.24% vs. 2.33%；[χ2] = 10.633，P < 0.01），但北部区域螺情回升的草洲数比例高于南部区域（53.49% vs. 15.76%；[χ2] = 26.966，P < 0.01）。对干旱后螺情回升洲滩的螺情指标进行纵向观察发现，螺情恢复至干旱前需1～5年，中位年数为2（1）年；当有螺草洲内活螺框出现率和活螺平均密度分别在2.11%和0.025 5只/0.1 m2及以上时，螺情更易出现反弹。结论 干旱对鄱阳湖区钉螺孳生产生了较明显的影响，使得螺情指标显著下降，其中南部区域影响更大；螺情恢复至干旱前需1～5年。

关键词: 钉螺, 血吸虫病, 干旱, 鄱阳湖区