Predators and pathogens often regulate the population dynamics of their prey or hosts. When species interact with both their predators and their pathogens, understanding each interaction in isolation may not capture the system's dynamics. For instance, predators can influence pathogen transmission via consumptive effects, such as feeding on infected prey, or non-consumptive effects, such as changing the prey's susceptibility to infection. A prey species' infection status can, in turn, influence predator's choice of prey and have negative fitness consequences for the predator. To test how intraguild predation (IGP), when predator and pathogen share the same prey/host, affects pathogen transmission, predator preference, and predator fitness, we conducted a series of experiments using a crop pest (Pseudoplusia includens), a generalist predator (Podisus maculiventris), and a generalist pathogen (Autographa californica multicapsid nuclear polyhedrovirus, AcMNPV). Using a field experiment, we quantified the effects of consumptive and non-consumptive predators on pathogen transmission. We found that a number of models provided similar fits to the data. These models included null models showing no effects of predation and models that included a predation effect. We also found that predators consumed infected prey more often when choosing between live infected or live healthy prey. Infected prey also reduced predator fitness. Developmental times of predators fed infected prey increased by 20% and longevity decreased by 45%, compared with those that consumed an equivalent number of non-infected prey. While this research shows an effect of the pathogen on intraguild predator fitness, we found no support that predators affected pathogen transmission.

中文翻译：

---

公会内部的捕食会降低捕食者的适应能力，从而对草食动物宿主中的病原体传播产生潜在的变化影响。

捕食者和病原体经常调节猎物或宿主的种群动态。当物种与它们的捕食者及其病原体相互作用时，孤立地了解每种相互作用可能无法捕获系统的动态。例如，掠食者可以通过诸如食用受感染猎物的食用效应或诸如改变猎物对感染的易感性等非食用效应来影响病原体的传播。猎物物种的感染状况反过来会影响捕食者对猎物的选择，并对捕食者产生不利的适应性后果。为了测试行内捕食（IGP）如何在捕食者和病原体共享相同的猎物/宿主时影响病原体传播，捕食者偏爱和捕食者适应性，我们使用农作物害虫（拟假单胞菌包括）进行了一系列实验，通才的捕食者（Podisus maculiventris）和通病的病原体（Autographa californica多衣壳核多角体病毒，AcMNPV）。通过现场实验，我们量化了食用和非食用捕食者对病原体传播的影响。我们发现许多模型提供了与数据相似的拟合度。这些模型包括显示没有捕食效果的空模型和包含捕食效果的模型。我们还发现，当在活感染或活健康的猎物之间进行选择时，捕食者会更频繁地消耗被感染的猎物。被感染的猎物也会降低捕食者的适应能力。与消耗了相同数量的未感染猎物的捕食者相比，喂食被感染猎物的捕食者的发育时间增加了20％，寿命降低了45％。