The influence of water on the migration of infective trichostrongyloid larvae onto grass
The influence of water on the migration of infective trichostrongyloid larvae onto grass
复制标题
水对感染性毛圆线虫幼虫向草上迁移的影响
作者：
J. V. Dijk;Eric R. Morgan
概述迫切需要详细了解水对经济上重要的毛状虫类感染幼虫迁徙的影响，以便为未来流行病学的预测模型提供资料。通过一系列室内实验，研究了水分对寄生线虫蝙蝠线虫、缠绕血线虫和周缘线虫从羊粪中迁移到草地上的影响。草坪地播种幼虫，幼虫是通过连续取样从草屑中回收的。游离水是幼虫从粪便中逃逸所必需的，但不是垂直迁移到草地上所必需的。当温度和相对湿度保持不变时，草本植物上的活幼虫种群比例在24 h后达到2(1-10)%左右的平台期，然后随时间变化不大。土壤和粪便中的幼虫形成了一个水库，这样修剪后草地上的幼虫数量保持了相似的比例。这些发现表明，自由幼虫继续随机移动。在寄生虫面临的权衡的背景下，讨论了对毛状虫类的流行病学的影响。
SUMMARY Detailed knowledge of the effects of water on the migration of infective larvae of economically important trichostrongyloid species is urgently needed to feed into prediction models of future epidemiology. The influence of water on the migration of the parasitic nematodes Nematodirus battus, Haemonchus contortus and Teladorsagia circumcincta from sheep dung onto grass was examined in a series of laboratory experiments. Turf plots were seeded with larvae, which were recovered from grass clippings by serial sampling. Free water was necessary for larvae to escape from dung, but not for vertical migration onto grass. When temperature and relative humidity were held constant, the proportion of a population of live larvae present on herbage reached a plateau of around 2 (1–10)% after 24 h, and then changed little over time. Larvae in soil and dung formed a reservoir, such that a similar proportion of the larval population was maintained on grass after clipping. These findings suggest continuing random movement of free larvae. Implications for the epidemiology of trichostrongyloid species are discussed in the context of trade-offs faced by the parasites.