Predator diversity, intraguild predation, and indirect effects drive parasite transmission
Predator diversity, intraguild predation, and indirect effects drive parasite transmission
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DOI：
10.1073/pnas.1415971112
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发表时间：
2015-03-10
影响因子：
11.1
通讯作者：
Beasley, Val R.
中科院分区：
文献类型：
--
作者：
Rohr, Jason R.;Civitello, David J.;Beasley, Val R.
人类正在改变全球生物多样性，传染病呈上升趋势；因此，人们有兴趣了解生物多样性的变化如何影响疾病。在这里，我们探索捕食者多样性如何影响寄生虫传播。在一项中观实验中，控制捕食者（幼虫蜻蜓和豆豆蝇）的密度和多样性，只吃自由生活的尾蚴（寄生吸虫）的非野生动物捕食者减少了蝌蚪的包囊蚴感染，而既吃寄生虫又吃蝌蚪宿主的野生动物捕食者则没有。这可能是因为IG捕食者减少了蝌蚪的密度和抗虫行为，增加了存活蝌蚪的人均暴露率（即通过密度和性状介导的效应），尽管它们消耗了寄生虫。一个数学模型表明，非IG捕食者减少了大寄生虫的感染，但IG捕食削弱了这种“稀释效应”，甚至可能增加寄生虫的负担。与实验和模型一致的是，一项湿地调查显示，IG捕食者的多样性与两栖动物的囊蚴负荷无关，而非IG捕食者的多样性与感染呈负相关。这些结果与捕食者多样性-害虫生物防治文献中出现的一般性结论惊人地相似，表明害虫防治可能存在一般机制，生物防治研究可能为疾病管理提供信息，反之亦然。总之，我们确定了捕食者的一般特征——它们落在一个IG捕食连续体上——这预示了它们减少感染和可能的害虫的能力。因此，管理捕食者群体是管理人类和野生动物疾病和害虫种群的一种未得到充分利用的工具。
Humans are altering biodiversity globally and infectious diseases are on the rise; thus, there is interest in understanding how changes to biodiversity affect disease. Here, we explore how predator diversity shapes parasite transmission. In a mesocosm experiment that manipulated predator (larval dragonflies and damselflies) density and diversity, non-intraguild (non-IG) predators that only consume free-living cercariae (parasitic trematodes) reduced metacercarial infections in tadpoles, whereas intraguild (IG) predators that consume both parasites and tadpole hosts did not. This likely occurred because IG predators reduced tadpole densities and anticercarial behaviors, increasing per capita exposure rates of the surviving tadpoles (i. e., via density-and trait-mediated effects) despite the consumption of parasites. A mathematical model demonstrated that non-IG predators reduce macroparasite infections, but IG predation weakens this "dilution effect" and can even amplify parasite burdens. Consistent with the experiment and model, a wetland survey revealed that the diversity of IG predators was unrelated to metacercarial burdens in amphibians, but the diversity of non-IG predators was negatively correlated with infections. These results are strikingly similar to generalities that have emerged from the predator diversity-pest biocontrol literature, suggesting that there may be general mechanisms for pest control and that biocontrol research might inform disease management and vice versa. In summary, we identified a general trait of predators-where they fall on an IG predation continuum-that predicts their ability to reduce infections and possibly pests in general. Consequently, managing assemblages of predators represents an underused tool for the management of human and wildlife diseases and pest populations.