Rohr Jason R, Civitello David J, Crumrine Patrick W, Halstead Neal T, Miller Andrew D, Schotthoefer Anna M, Stenoien Carl, Johnson Lucinda B, Beasley Val R
Department of Integrative Biology, University of South Florida, Tampa, FL 33620;
Departments of Biological Sciences and Geography and Environment, Rowan University, Glassboro, NJ 08028;
Proc Natl Acad Sci U S A. 2015 Mar 10;112(10):3008-13. doi: 10.1073/pnas.1415971112. Epub 2015 Feb 23.
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.
人类正在全球范围内改变生物多样性，传染病也在不断增加；因此，人们对于了解生物多样性的变化如何影响疾病产生了兴趣。在此，我们探讨捕食者多样性如何影响寄生虫传播。在一项中宇宙实验中，我们操纵了捕食者（蜻蜓和豆娘幼虫）的密度和多样性，结果发现，仅捕食自由生活尾蚴（寄生吸虫）的非集团内（非IG）捕食者减少了蝌蚪体内的后尾蚴感染，而既捕食寄生虫又捕食蝌蚪宿主的集团内（IG）捕食者则没有。这种情况可能是因为IG捕食者降低了蝌蚪密度并减少了抗尾蚴行为，尽管它们捕食了寄生虫，但却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）。一个数学模型表明，非IG捕食者会减少大型寄生虫感染，但IG捕食会削弱这种“稀释效应”，甚至可能增加寄生虫负担。与实验和模型一致，一项湿地调查显示，IG捕食者的多样性与两栖动物体内的后尾蚴负担无关，但非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，这表明可能存在害虫防治的一般机制，生物防治研究可能为疾病管理提供参考，反之亦然。总之，我们确定了捕食者的一个一般特征——它们在IG捕食连续体上的位置——这预测了它们减少感染以及可能减少害虫的能力。因此，管理捕食者组合是一种尚未充分利用的工具，可用于管理人类和野生动物疾病以及害虫种群。
