Abstract: Objective　To investigate the changes in distribution of Oncomelania hupensis snails in forestlands in Songjiang District, Shanghai Municipality from 2009 to 2023, so as to provide insights into formulation of O. hupensis snail surveillance programs. Methods　The reports on O. hupensis snail surveillance in Songjiang District, Shanghai Municipality from 2009 to 2023 were collected, and the snail surveillance data in forestlands were extracted. The trends in the proportion of areas with snails in forestlands in total areas with snails, occurrence of frames with living snails and density of living snails were evaluated using a Joinpoint regression model in Songjiang District from 2009 to 2023, and the annual percent change (APC) and average annual percent change (AAPC). Results　A total of 40 sites with snails were found in forestlands in 14 administrative villages of 4 townships, Songjiang District, Shanghai Municipality from 2009 to 2023. A total of 39 065 frames were surveyed for snails in settings covering an area of 609 600 m2, and there were 6 084 frames with snails, covering 151 250 m2 snail habitats. A total of 22 210 snails were captured, with the highest density of 260.00 snails/0.1 m2, and 6 262 snails were dissected, with no Schistosoma japonicum infection identified in snails. The proportion of areas with snails in forestlands in total areas with snails appeared a tendency towards a rise in forestlands in Songjiang District, Shanghai Municipality from 2009 to 2023 (APC = AAPC = 24.9%, P > 0.05); however, there were no turning points in the trend curve, with the highest proportion seen in 2009 (53.81%), the lowest in 2011 and 2023 (both 0) and a mean proportion of 24.81%. The occurrence of frames with living snails appeared a tendency towards a rise from 2009 to 2023 (APC = AAPC = 41.5%, P > 0.05); however, there were no turning points in the trend curve, with the highest occurrence in 2009 (53.81%), the lowest in 2011 and 2013 (both 0), and the mean occurrence of 15.57%. In addition, the density of living snails appeared a tendency towards a rise from 2009 to 2023 (APC = AAPC = 55.0%, P > 0.05); however, there were no turning points in the trend curve, with the highest density in 2023 (0.96 snails/0.1 m2), the lowest in 2011 and 2013 (both 0), and a mean density of 0.57 snails/0.1 m2. Conclusions　The difficulty in O. hupensis snail control and risk of imported snails appeared a tendency towards a rise in forestlands in Songjiang District, Shanghai Municipality over years from 2009 to 2023. Supervision and assessment prior to seedling transplantation and intensified surveillance post⁃transplantation are recommended to reduce the risk of O. hupensis snail importation and spread.

Key words: Oncomelania hupensis, Forestland, Joinpoint regression analysis, Songjiang District

摘要： 目的　分析2009—2023年上海市松江区林地螺情变化，为制定松江区螺情监测方案提供参考依据。方法　收集2009—2023年上海市松江区螺情监测工作报表，提取林地钉螺调查数据，采用Joinpoint回归模型分别对有螺面积比、活螺框出现率及活螺密度进行建模分析，计算2009—2023年各指标年度变化百分比（annual percent change，APC）、年均变化百分比（average annual percent change，AAPC）。结果　2009—2023年，上海市松江区累计在4个镇14个行政村发现林地螺点40个；累计调查钉螺39 065框，调查面积609 600 m2，其中有螺框6 084框、有螺面积151 250 m2；捕获钉螺22 210只，最高钉螺密度260.00只/0.1 m2；解剖钉螺6 262只，未发现血吸虫感染阳性钉螺。2009—2023年，上海市松江区林地有螺面积比呈上升趋势，但无统计学意义（APC = AAPC = 24.9%，P > 0.05），趋势曲线无连接点；最高在2009年（53.81%）、最低在2011年和2013年（均为0），平均24.81%。2009—2023年，上海市松江区林地活螺框出现率呈上升趋势，但无统计学意义（APC = AAPC = 41.5%，P > 0.05），趋势曲线无连接点，总体呈单调递增趋势；最高在2009年（53.81%）、最低在2011年和2013年（均为0），平均15.57%。2009—2023年，上海市松江区林地活螺密度呈上升趋势，但无统计学意义（APC = AAPC = 55.0%，P > 0.05），趋势曲线无连接点；最高在2023年（0.96只/0.1 m2）、最低在2011年和2013年（均为0），平均0.57只/ 0.1 m2。结论　2009—2023年上海市松江区林地钉螺控制难度及输入风险呈逐年增加趋势；建议采取苗木移植前监管评估、移植后加强监测频次等措施，以降低钉螺输入及扩散风险。

关键词: 钉螺, 林地, 苗木移植, Joinpoint回归, 松江区