How Changes in Diet Can Enable Caterpillars to Overcome Parasite Infection

Michael S. Singer，Proposal IOS-0744676饮食的改变如何使毛毛虫克服寄生虫感染进食行为的改变可以使个体动物治愈寄生虫感染或其他生理痛苦。所有动物都有免疫防御能力，根据个体的饮食，免疫防御能力可能会发生变化。此外，食草动物如毛毛虫可能会通过摄入和积累它们所吃植物中的有毒化学物质来杀死它们的寄生虫。本研究计划将调查这两种手段的抗寄生虫行为的羊毛熊毛虫Grammia geneura。从先前的研究中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的饮食选择与未寄生毛毛虫。第二，为了评估特定饮食在抗寄生虫中的作用，将测试寄生和未寄生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，寄生虫将在反映不同毛虫饮食的人工饮食中饲养。新感染了潜在致命的寄生蝇追寄蝇梅拉的毛虫，预计会选择营养丰富的饮食来增强其免疫抵抗力。预计这种机制对毛虫的生理成本最小。然而，受到晚期寄生虫感染威胁的毛毛虫预计会选择富含称为吡咯里西定生物碱的天然植物毒素的饮食。摄入异常大量的生物碱预计对毛虫来说是生理上昂贵的，因此被用作最后的手段。这项研究的更广泛的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有关动物健康，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.