Singer Michael S, Mason Peri A, Smilanich Angela M
Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA; Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO 80309, USA; Department of Biology, University of Nevada Reno, Reno, NV 89557, USA
Department of Biology, Wesleyan University, 52 Lawn Avenue, Middletown, CT 06459, USA; Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO 80309, USA; Department of Biology, University of Nevada Reno, Reno, NV 89557, USA.
Integr Comp Biol. 2014 Nov;54(5):913-21. doi: 10.1093/icb/icu089. Epub 2014 Jun 20.
A rapidly advancing area of ecological immunology concerns the effects of diet on animals' immunological responses to parasites and pathogens. Here, we focus on diet-mediated ecological immunology in herbivorous insects, in part because these organisms commonly experience nutritional limitations from their diets of plants. Nutritional immunology highlights nutrient-based trade-offs between immunological and other physiological processes as well as trade-offs among distinct immunological processes. This field reveals that nutrition influences the quality and quantity of immunological defense in herbivorous insects, and conversely that nutritional intake by herbivorous insects can be an adaptive response to the specific types of immune-challenge they face in the context of other physiological processes. Because the diets of herbivores challenge them physiologically with plants' secondary metabolites, another area of study analyzes constraints on immunological defense imposed by secondary metabolites of plants in the diets of herbivorous insects. Alternatively, some herbivores can use secondary metabolites as medicine against parasites or pathogens. Animal-medication theory makes an important contribution to ecological immunology by distinguishing prophylactic and therapeutic mechanisms of anti-parasite defense. Integrating ideas from animal-medication and nutritional immunology, we outline a conceptual framework in which the immunological role of the diet consists of mechanisms of prophylaxis, therapy, compensation, and combinations thereof. Then, we use this framework to organize findings from our own research on diet-mediated ecological immunology of woolly bear caterpillars. We show evidence that the woolly bear caterpillar, Grammia incorrupta (Hy. Edwards) (Lepidoptera, Erebidae, and Arctiinae), can employ both diet-mediated prophylaxis and therapy. First, increased consumption of carbohydrate-biased food prior to immune-challenge increased its melanization-response. Second, increased consumption of pyrrolizidine alkaloids (PAs) more than 24 h after parasitism by tachinid flies resulted in anti-parasite resistance. Caterpillars reduced feeding on protein-biased food within 24 h after immune-challenge, showing evidence of illness-induced anorexia. We synthesize our work to generate the hypothesis that a diet-mediated defense by the host against parasites acts as a temporally explicit, multi-stage process.
生态免疫学中一个迅速发展的领域关注饮食对动物针对寄生虫和病原体的免疫反应的影响。在此，我们聚焦于食草昆虫中由饮食介导的生态免疫学，部分原因是这些生物通常会因其植物性饮食而面临营养限制。营养免疫学强调了基于营养的免疫和其他生理过程之间的权衡，以及不同免疫过程之间的权衡。该领域揭示，营养会影响食草昆虫免疫防御的质量和数量，反之，食草昆虫的营养摄入可能是它们在其他生理过程背景下面对特定类型免疫挑战的一种适应性反应。由于食草动物的饮食会用植物的次生代谢产物对它们进行生理挑战，另一个研究领域分析了食草昆虫饮食中植物次生代谢产物对免疫防御的限制。或者，一些食草动物可以将次生代谢产物用作对抗寄生虫或病原体的药物。动物用药理论通过区分抗寄生虫防御的预防和治疗机制，为生态免疫学做出了重要贡献。整合动物用药和营养免疫学的观点，我们概述了一个概念框架，其中饮食的免疫作用包括预防、治疗、补偿及其组合机制。然后，我们使用这个框架来整理我们自己关于灯蛾毛虫饮食介导的生态免疫学研究的结果。我们展示了证据，表明灯蛾毛虫（Grammia incorrupta (Hy. Edwards)，鳞翅目，夜蛾科，灯蛾亚科）可以采用饮食介导的预防和治疗方法。首先，在免疫挑战前增加对富含碳水化合物食物的消耗会增强其黑化反应。其次，在被寄蝇寄生超过24小时后增加对吡咯里西啶生物碱（PAs）的消耗会产生抗寄生虫抗性。毛虫在免疫挑战后24小时内减少对富含蛋白质食物的取食，显示出疾病诱导厌食的证据。我们综合我们的研究成果，提出一个假设，即宿主通过饮食介导对寄生虫的防御是一个具有时间特异性的多阶段过程。
