目的 探讨鄱阳湖区钉螺时空分布动态及影响因素,为制定鄱阳湖区钉螺控制措施提供科学依据。 方法 选择鄱阳湖南湖区的赣江南支和北支、抚河、信江、饶河、修河与赣江汇合处5大入湖河流尾闾和北湖区入江水道的35块草洲为研究对象,分析草洲有螺面积、感染螺面积、活螺平均密度和感染螺平均密度等指标。同步收集各草洲3次钉螺普查数据、不同水文站水位数据、草洲高程及相关灭螺方式等信息,采用秩和检验法比较活螺平均密度和感染螺平均密度的差异。 结果 第一、第二和第三次普查（1982、2002、2017年）发现的有螺面积分别为8 574.5、9 014.3和5 099.8 hm²,感染螺面积分别为172.0、91.0和0 hm²;活螺平均密度分别为0.7（48 833/69 750）、1.6（134 534/83 387）和0.3只/0.1 m²（33 189/97 315）,感染螺平均密度分别为2.5 × 10^-3（172/69 750）、1.1 × 10^-3（91/83 387）和0只/0.1 m²。除1985年外,1980-2002年（横跨第一次、第二次普查）的平均年最高水位均超过草洲上高程（18 m）,平均年最低水位低于草洲下高程（13 m）;2003-2016年（横跨第二次、第三次普查）,有7个年份的平均年最高水位低于草洲上高程,平均年最低水位低于1980-2002年结果。第二次普查后,水位因素导致鄱阳湖丰水期上高程的草洲难以被淹,枯水期低洼泥滩显露时间更长、草洲更干旱。鄱阳湖3次普查测得草洲的高程没有变化,根据草洲上高程平均值,由高至低排序,依次为信江（16.7 m）、赣江北支（16.5 m）、抚河（16.5 m）、修河与赣江汇合处（16.4 m）、赣江南支（16.3 m）、饶河（15.7 m）和入江水道（15.0 m）。第一次普查时灭螺草洲和自然草洲的活螺平均密度分别0.5只/0.1 m²（18 227/34 531）和0.9只/0.1 m²（36 605/35 219）,感染螺平均密度分别为1.7 × 10^-3只/0.1 m²（58/34 531）、3.2 × 10^-3只/0.1m²(114/35 219);第二次普查时灭螺草洲和自然草洲的活螺平均密度分别1.1只/0.1 m²（37 494/34 755）和2只/0.1 m²（97 041/48 632）,感染螺平均密度分别为1.7 × 10^-3只/0.1 m²（58/34 755）和0.7 × 10^-3只/0.1 m²（33/48 632）;第三次普查时灭螺草洲和自然草洲的活螺平均密度分别0.3只/0.1 m²（15 180/44 417）和0.3只/0.1 m²（18 009/52 898）,感染螺平均密度分别为0,差异均无统计学意义（P > 0.05)。 结论 鄱阳湖区钉螺消长受水位、草洲高程和人工干预灭螺等综合因素的影响,南湖区草洲高程较高区域的钉螺呈现往西北部和北湖区低高程草洲退移的趋势。药物灭螺措施可快速降低草洲活螺平均密度,但钉螺低密度状态下药物灭螺措施对草洲灭螺的效果不佳。

Objective To investigate the spatial and temporal distribution of Oncomelania hupensis in Poyang Lake area and the influencing factors related to the spread of O. hupensi, so as to provide a scientific basis for formulating measures for the control of O. hupensi in the endemic lake area. Methods Total 35 marshland blocks located at the confluences of rivers at the north and south banks of Poyang Lake were chosen as survey sites. The data for three surveys including area with O. hupensi, the area with infected O. hupensi, average density of living O. hupensi and average density of infected living O. hupensi, hydrologic water level, the bank marshland height and O. hupensi control measures were collected. Average density of living O. hupensi and infected living O. hupensi were analyzed by using rank sum test. Results For the 1^st, 2^nd and the 3^rd O. hupensi survey（1982, 20012, 2017）, the area with O. hupensis was 8 574.5, 9 014.3 and 5 099.8 hm², the area with infected O. hupensiwas 172.0, 91.0 and 0 hm², the average density of living O. hupensi was 0.7(48 833/69 750), 1.6 (134 534/83 387) and 0.3/0.1 m² (33 189/97 315), and the average density of infected O. hupensis was 2.5 × 10^-3 (172/69 750), 1.1 × 10^-3 (91/83 387) and 0 hm², respectively. Except 1985, the average annual maximum water level during 1980-2002(including 1^st and 2^nd snail surveys) was higher than the upper elevation of marshland(18 m), and the average annual minimum water level was lower than the lower elevation of marshland (13 m). From 2003 to 2016 (including 2^nd and 3^rd surveys), the mean annual maximum water level was lower than the upper elevation of the marshland for 7 years, and the mean annual minimum water level was lower than that during 1980-2002. After the second survey, the lower lake water level was not able to merge the marshland during the flood season and the basin of lake was exposed for a longer time and the marshland was dried out during the drought season. There was no change for the elevation of marshland among the three surveys. The mean elevation of marshland from high to low was Xinjiang (16.7 m), Ganjiang North Branch(16.5 m), Fu River (16.5 m), Xiuhe and Ganjiang confluence (16.4 m), Ganjiang South Branch (16.3 m), Rao River (15.7 m) and river entry channel (15.0 m). For the first survey, the average density of living O. hupensi in the areas with and without O. hupensis control was 0.5/0.1 m² （18 227/34 531）and 0.9/0.1 m²（36 605/35 219）, the density of infected O. hupensis in the areas with and without O. hupensis control was 1.7 × 10^-3/0.1m²(58/34 531) and 3.2 × 10^-3/0.1 m² (114/35 219), respectively. For the second survey, the density of living O. hupensis was 1.1/0.1 m² （37 494/34 755） in O. hupensis control area and 2/0.1 m² （97 041/48 632） in area without O. hupensis control, the density of infected O. hupensis was 1.7 × 10^-3/0.1 m²(58/34 755) in O. hupensis control area and 0.7 × 10^-3/0.1 m² (33/48 632) in area without O. hupensis control. For the third survey, the density of living O. hupensis in the areas with and without O. hupensis control was 0.3/0.1 m²（15 180/44 417）and 0.3/0.1 m²（18 009/52 898）, the density of infected O. hupensis in the areas with and without O. hupensis control was 0, respectively, without statistical significance (P > 0.05). Conclusion The growth and spread of O. hupensis in Poyang Lake area was affected by lake water level, elevation of marshland and the snail control intervention. O. hupensis in the higher elevations of marshland in the Southern Lake Area show a trend of retreating to the northwest and the low elevations of marshland in the Northern Lake Area. Application of molluscicides can quickly reduce the O. hupensis density on the marshland, but has low effect on the snail control when the snail density is low.