Welsh Jennifer E, Liddell Caroline, VAN DER Meer Jaap, Thieltges David W
NIOZ Royal Netherlands Institute for Sea Research,Department of Coastal Systems,PO Box 59, 1790 AB den Burg,Texel,the NetherlandsandUtrecht University,Postbus 80125, 3508 TC,Utrecht,the Netherlands.
Parasitology. 2017 Nov;144(13):1775-1782. doi: 10.1017/S0031182017001056. Epub 2017 Jul 19.
In parasites with complex life cycles the transmission of free-living infective stages can be influenced by ambient community diversity, in particular via predation. Here, we experimentally investigated whether parasite density and the presence of alternative prey can alter predation rates on free-living cercarial stages of a marine trematode by several non-host predators. All four predator species consumed increasing numbers of cercariae with an increase in cercarial density, indicating that the removal of cercariae by predators is effective over a range of natural densities as well as in the presence of alternative prey for a number of predators typical of marine ecosystems. However, the relative removal rates and the effects of cercarial density and alternative prey differed among predator species. In barnacles and shrimps, significant interactive effects of cercarial density and alternative prey on cercarial predation occurred while in oysters and crabs cercarial removal rates were unaffected by both factors. As changes in cercarial densities directly translate into changes in infection levels in down-stream hosts in this parasite-host system, the observed predator-specific responses suggest that cercarial predation effects on disease risks will depend on the specific species composition of ambient communities and not on non-host biodiversity per se.
在具有复杂生命周期的寄生虫中，自由生活感染阶段的传播可能会受到周围群落多样性的影响，尤其是通过捕食作用。在此，我们通过实验研究了寄生虫密度和替代猎物的存在是否会改变几种非宿主捕食者对一种海洋吸虫自由生活尾蚴阶段的捕食率。随着尾蚴密度的增加，所有四种捕食者物种消耗的尾蚴数量都在增加，这表明在一系列自然密度下以及在存在多种典型海洋生态系统捕食者的替代猎物的情况下，捕食者对尾蚴的清除都是有效的。然而，捕食者物种之间的相对清除率以及尾蚴密度和替代猎物的影响有所不同。在藤壶和虾类中，尾蚴密度和替代猎物对尾蚴捕食产生了显著的交互作用，而在牡蛎和螃蟹中，尾蚴清除率不受这两个因素的影响。由于在这个寄生虫 - 宿主系统中，尾蚴密度的变化直接转化为下游宿主感染水平的变化，观察到的捕食者特异性反应表明，尾蚴捕食对疾病风险的影响将取决于周围群落的具体物种组成，而不是非宿主生物多样性本身。
