How Changes in Diet Can Enable Caterpillars to Overcome Parasite Infection

Michael S. Singer，提案 IOS-0744676 饮食的改变如何使毛毛虫克服寄生虫感染喂养行为的改变可以使个体动物治愈寄生虫感染或其他生理困扰。所有动物都具有免疫防御能力，其强度可能会根据个人饮食而改变。此外，毛毛虫等食草动物可能会通过摄入和积累所吃植物中的有毒化学物质来杀死寄生虫。该研究项目将研究毛毛熊毛毛虫 Grammia 属的这两种抗寄生虫行为。之前的研究怀疑该物种通过其摄食选择来抵御天然寄生虫。首先，行为实验将表征实验寄生毛毛虫相对于未寄生毛毛虫的饮食选择。其次，为了评估特定饮食在抵抗寄生虫方面的作用，将测试被寄生和未被寄生的毛毛虫在不同饮食中的存活率。第三，生理实验将评估这些饮食对毛毛虫对寄生虫的免疫反应的影响。最后，为了分析没有免疫系统的毛虫饮食的直接影响，将用反映不同毛虫饮食的人工饲料饲养寄生虫。刚被潜在致命的寄生蝇 Exorista mella 感染的毛毛虫预计会选择营养丰富的饮食来增强其免疫抵抗力。这种机制预计会给毛毛虫带来最小的生理成本。然而，受到后期寄生虫感染威胁的毛毛虫预计会选择富含天然植物毒素（称为吡咯里西啶生物碱）的饮食。摄入异常大量的生物碱预计对毛毛虫来说是生理上代价高昂的，因此被用作最后的手段。这项研究的更广泛影响包括培训不同的学生和博士后研究员将行为、生理学和生态学与动物健康联系起来。通过公开演讲，该项目还将教育公众了解动物健康、行为和环境之间的科学联系。

Michael S. Singer, Proposal IOS-0744676How changes in diet can enable caterpillars to overcome parasite infectionChanges in feeding behavior can enable individual animals to cure themselves of parasite infections or other physiological distress. All animals have immunological defenses that can potentially change in strength based on an individual's diet. In addition, herbivores such as caterpillars may kill their parasites by ingesting and accumulating toxic chemicals found in the plants they eat. This research project will investigate these two means of anti-parasite behavior by the woolly bear caterpillar Grammia geneura. This species is suspected from previous study to ward off natural parasites through its feeding choices. First, behavioral experiments will characterize the dietary choices of experimentally parasitized caterpillars in relation to unparasitized caterpillars. Second, to evaluate the role of specific diets in resistance against parasites, the survival of parasitized and unparasitized caterpillars on different diets will be tested. Third, physiological experiments will evaluate the effects of these diets on the caterpillar's immune response to parasites. Finally, to analyze direct effects of caterpillar diet without the immune system, the parasites will be raised on artificial diets that reflect different caterpillar diets. Caterpillars newly infected by the potentially lethal, parasitic fly Exorista mella, are expected to choose a nutritious diet to enhance their immunological resistance. This mechanism is expected to carry minimal physiological costs for the caterpillar. However, caterpillars threatened by late-stage parasitic infections are expected to choose a diet rich in natural plant toxins called pyrrolizidine alkaloids. Ingesting unusually large quantities of alkaloids is expected to be physiologically costly for the caterpillar, and thus used as a last resort. The broader impacts of this research include training diverse students and a post-doctoral fellow in linking behavior, physiology, and ecology to animal health. Through public presentations, this project will also educate the public about the scientific link between animal health, behavior, and the environment.