Luong Lien T, Grear Daniel A, Hudson Peter J
Center for Infectious Disease Dynamics, Department of Biology, 208 Mueller Laboratory, The Pennsylvania State University, University Park, PA 16802, USA.
Center for Infectious Disease Dynamics, Department of Biology, 208 Mueller Laboratory, The Pennsylvania State University, University Park, PA 16802, USA.
Int J Parasitol. 2014 Sep;44(10):737-42. doi: 10.1016/j.ijpara.2014.05.004. Epub 2014 Jun 12.
Many complex life cycle parasites rely on predator-prey interactions for transmission, whereby definitive hosts become infected via the consumption of an infected intermediate host. As such, these trophic parasites are embedded in the larger community food web. We postulated that exposure to infection and, hence, parasite transmission are inherently linked to host foraging ecology, and that perturbation of the host-resource dynamic will impact parasite transmission dynamics. We employed a field manipulation experiment in which natural populations of the eastern chipmunk (Tamias striatus) were provisioned with a readily available food resource in clumped or uniform spatial distributions. Using replicated longitudinal capture-mark-recapture techniques, replicated supplemented and unsupplemented control sites were monitored before and after treatment for changes in infection levels with three gastro-intestinal helminth parasites. We predicted that definitive hosts subject to food supplementation would experience lower rates of exposure to infective intermediate hosts, presumably because they shifted their diet away from the intermediate host towards the more readily available resource (sunflower seeds). As predicted, prevalence of infection by the trophically transmitted parasite decreased in response to supplemental food treatment, but no such change in infection prevalence was detected for the two directly transmitted parasites in the system. The fact that food supplementation only had an impact on the transmission of the trophically transmitted parasite, and not the directly transmitted parasites, supports our hypothesis that host foraging ecology directly affects exposure to parasites that rely on the ingestion of intermediate hosts for transmission. We concluded that the relative availability of different food resources has important consequences for the transmission of parasites and, more specifically, parasites that are embedded in the food web. The broader implications of these findings for food web dynamics and disease ecology are discussed.
许多具有复杂生命周期的寄生虫依靠捕食者与猎物之间的相互作用来进行传播，即终末宿主通过摄食受感染的中间宿主而被感染。因此，这些营养寄生虫嵌入在更大的群落食物网之中。我们推测，感染暴露以及寄生虫传播与宿主觅食生态本质上存在关联，并且宿主-资源动态的扰动会影响寄生虫传播动态。我们进行了一项野外操纵实验，为东部花栗鼠（美洲花鼠）的自然种群提供了空间分布呈聚集或均匀状态的现成食物资源。运用重复的纵向标记重捕技术，在处理前后对重复设置的补充食物和未补充食物的对照地点进行监测，以观察三种胃肠道蠕虫寄生虫感染水平的变化。我们预测，接受食物补充的终末宿主接触感染性中间宿主的几率会降低，大概是因为它们将饮食从中间宿主转向了更容易获取的资源（向日葵种子）。正如预测的那样，营养传播寄生虫的感染率因补充食物处理而下降，但对于系统中的两种直接传播寄生虫，未检测到感染率有此类变化。食物补充仅对营养传播寄生虫的传播有影响，而对直接传播寄生虫没有影响，这一事实支持了我们的假设，即宿主觅食生态直接影响对依赖摄食中间宿主进行传播的寄生虫的接触。我们得出结论，不同食物资源的相对可获得性对寄生虫的传播具有重要影响，更具体地说，对嵌入食物网中的寄生虫有重要影响。我们还讨论了这些发现对食物网动态和疾病生态学的更广泛意义。
