Graham Robert I, Deacutis Juliane M, Pulpitel Tamara, Ponton Fleur, Simpson Stephen J, Wilson Kenneth
School of Biological Sciences, University of Sydney, NSW 2006, Australia; Charles Perkins Centre, University of Sydney, NSW 2006, Australia; Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
School of Biological Sciences, University of Sydney, NSW 2006, Australia; Charles Perkins Centre, University of Sydney, NSW 2006, Australia; Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
J Insect Physiol. 2014 Oct;69:27-34. doi: 10.1016/j.jinsphys.2014.05.015. Epub 2014 May 24.
There is growing evidence to suggest that hosts can alter their dietary intake to recoup the specific resources involved in mounting effective resistance against parasites and pathogens. We examined macronutrient ingestion and disease-resistance in the Australian plague locust (Chortoicetes terminifera), challenged with a fungal pathogen (Metarhizium acridum) under dietary regimes varying in their relative amounts of protein and digestible carbohydrate. Dietary protein influenced constitutive immune function to a greater extent than did carbohydrate, indicating higher protein costs of mounting an immune defence than carbohydrate or overall energy costs. However, it appears that increased immune function, as a result of greater protein ingestion, was not sufficient to protect locusts from fungal disease. We found that locusts restricted to diets high in protein (P) and low in carbohydrate (C) were more likely to die of a fungal infection than those restricted to diets with a low P:C ratio. We hypothesise that the fungus is more efficient at exploiting protein in the insect's haemolymph than the host is at producing immune effectors, tipping the balance in favour of the pathogen on high-protein diets. When allowed free-choice, survivors of a fungus-challenge chose a less-protein-rich diet than those succumbing to infection and those not challenged with fungus locusts. These results are contrary to previous studies on caterpillars in the genus Spodoptera challenged with bacterial and baculoviral pathogens, indicating that nutrient ingestion and pathogen resistance may be a complex interaction specific to different host species and disease agents.
越来越多的证据表明，宿主可以改变其饮食摄入，以补充在有效抵抗寄生虫和病原体过程中所涉及的特定资源。我们研究了澳大利亚疫蝗（Chortoicetes terminifera）在受到真菌病原体（绿僵菌）攻击时的常量营养素摄入和抗病能力，这些蝗虫处于蛋白质和可消化碳水化合物相对含量不同的饮食模式下。饮食中的蛋白质对组成性免疫功能的影响比碳水化合物更大，这表明进行免疫防御所需的蛋白质成本高于碳水化合物或总体能量成本。然而，摄入更多蛋白质导致的免疫功能增强似乎不足以保护蝗虫免受真菌疾病的侵害。我们发现，与限制在低蛋白碳水比饮食中的蝗虫相比，限制在高蛋白（P）低碳水化合物（C）饮食中的蝗虫更有可能死于真菌感染。我们推测，真菌在利用昆虫血淋巴中的蛋白质方面比宿主产生免疫效应物更有效，这使得在高蛋白饮食中病原体占据优势。当蝗虫可以自由选择时，受到真菌攻击的幸存者选择的饮食中蛋白质含量低于死于感染的蝗虫以及未受到真菌攻击的蝗虫。这些结果与之前关于受到细菌和杆状病毒病原体攻击的夜蛾属毛虫的研究结果相反，表明营养摄入和病原体抗性可能是特定于不同宿主物种和病原体的复杂相互作用。
