Madsen H
Acta Trop. 1983 Sep;40(3):297-306.
Helisoma duryi is a planorbid snail, which has been suggested as biological control agent against the intermediate hosts of schistosomiasis. This snail species has been present in a sugar estate in northern Tanzania since 1972. In January 1981 a snail survey was done in this area in order to determine the distribution and abundance of H. duryi relative to other freshwater snail species. The distribution of H. duryi was found to be restricted to a few drains, while Biomphalaria pfeifferi, Bulinus natalensis, and Lymnaea natalensis were widespread. However, where H. duryi was found, no or very few B. pfeifferi were recorded indicating either competitive interactions between the two species or perhaps differences in the ecological preferences of the two species. No competitive interactions were indicated between H. duryi and B. natalensis. The apparent failure of H. duryi to spread in the area might be due to regular molluscicide application to the canal system and drainage canals, where H. duryi did not occur.
杜氏扁卷螺是一种盘螺科蜗牛，有人提议将其作为控制血吸虫病中间宿主的生物制剂。自1972年以来，这种蜗牛就出现在坦桑尼亚北部的一个甘蔗种植园里。1981年1月，该地区进行了一次蜗牛调查，以确定杜氏扁卷螺相对于其他淡水蜗牛种类的分布和数量。结果发现，杜氏扁卷螺的分布仅限于少数排水沟，而费氏双脐螺、纳塔尔小泡螺和纳塔尔椎实螺分布广泛。然而，在发现杜氏扁卷螺的地方，记录到的费氏双脐螺数量很少或没有，这表明这两个物种之间存在竞争相互作用，或者这两个物种在生态偏好上存在差异。杜氏扁卷螺和纳塔尔小泡螺之间未显示出竞争相互作用。杜氏扁卷螺在该地区未能扩散，可能是由于定期向杜氏扁卷螺未出现的运河系统和排水渠道施用杀螺剂。
