Most demonstrated trophic cascades originate with predators, but infectious agents can also cause top-down indirect effects in ecosystems. Here we synthesize the literature on trophic cascades initiated by infectious agents including parasitoids, pathogens, parasitic castrators, macroparasites, and trophically transmitted parasites. Like predators, infectious agents can cause density-mediated and trait-mediated indirect effects through their direct consumptive and nonconsumptive effects respectively. Unlike most predators, however, infectious agents are not fully and immediately lethal to their victims, so their consumptive effects can also trigger trait-mediated indirect effects. We find that the frequency of trophic cascades reported for different consumer types scales with consumer lethality. Furthermore, we emphasize the value of uniting predator–prey and parasite–host theory under a general consumer–resource framework.

大多数已证明的营养级联起源于捕食者，但传染原也可能对生态系统造成自上而下的间接影响。在这里，我们综合了由营养因子（包括寄生虫，病原体，寄生cast虫，大寄生虫和营养传播的寄生虫）引发的营养级联的文献。像掠食者一样，传染原可以通过直接消耗和非消耗作用分别引起密度介导和性状介导的间接作用。但是，与大多数掠食者不同，传染原并未完全和立即对其受害者致死，因此其消耗性作用还可能触发性状介导的间接作用。我们发现，针对不同消费者类型的营养级联反应的频率随消费者致死率而变化。此外，