Brackenbury T D
Biological Control Products, Pinetown, South Africa.
Ann Trop Med Parasitol. 1999 Jul;93(5):511-8. doi: 10.1080/00034989958258.
Synthetic molluscicides have proved too expensive for most countries wanting to include snail control in their anti-schistosomiasis programmes. An alternative, which is not only cheaper but also promotes self-reliance and empowerment of the affected communities, is the use of molluscicidal plants. An often-cited limitation to using such natural products is the geographical variation in the toxicity of candidate species. The geographical variation in the molluscicidal activity of Apodytes dimidiata was investigated in South Africa. Leaves of this plant were collected from six, widely separate localities within the areas of the country where schistosomiasis is endemic. The results of bio-assays using the intermediate host snail, Bulinus africanus, clearly showed that variation in toxicity did exist and appeared to be correlated with the range in mean annual temperatures and altitude where the plants grew. Whether the variation was a phenoplastic response to the environment or genetically determined still has to be investigated. Nevertheless, a thorough knowledge of the geographical variation in the level of the active compound(s) in the candidate plants in endemic areas will be needed prior to the implementation of plant-propagation and snail-control programmes.
对于大多数希望在其抗血吸虫病计划中纳入灭螺措施的国家来说，合成杀螺剂已被证明过于昂贵。另一种选择，不仅成本更低，而且能促进受影响社区的自力更生和赋权，那就是使用杀螺植物。使用这类天然产品的一个经常被提及的限制是候选物种毒性的地理差异。在南非对迪氏风车子（Apodytes dimidiata）的杀螺活性的地理差异进行了研究。这种植物的叶子采自该国血吸虫病流行地区内六个相距甚远的地点。使用中间宿主蜗牛非洲泡螺（Bulinus africanus）进行生物测定的结果清楚地表明，毒性差异确实存在，而且似乎与植物生长地的年平均温度范围和海拔高度有关。这种差异是对环境的表型可塑性反应还是由基因决定的，仍有待研究。然而，在实施植物繁殖和灭螺计划之前，需要深入了解流行地区候选植物中活性化合物水平的地理差异。
