Lee K P, Cory J S, Wilson K, Raubenheimer D, Simpson S J
Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
Proc Biol Sci. 2006 Apr 7;273(1588):823-9. doi: 10.1098/rspb.2005.3385.
Mounting effective resistance against pathogens is costly in terms of energy and nutrients. However, it remains unexplored whether hosts can offset such costs by adjusting their dietary intake so as to recoup the specific resources involved. We test this possibility by experimentally challenging caterpillars (Spodoptera littoralis) with a highly virulent entomopathogen (nucleopolyhedrovirus), under dietary regimes varying in the content of protein and digestible carbohydrate. We found that dietary protein influenced both resistance to pathogen attack and constitutive immune function to a greater extent than did dietary carbohydrate, indicating higher protein costs of resistance than energy costs. Moreover, when allowed to self-compose their diet, insects surviving viral challenge increased their relative intake of protein compared with controls and those larvae dying of infection, thus demonstrating compensation for protein costs associated with resistance. These results suggest that the change in the host's nutritional demands to fight infection induces a compensatory shift in feeding behaviour.
对病原体产生有效的抵抗力在能量和营养方面代价高昂。然而，宿主是否能够通过调整饮食摄入量来抵消这些成本，从而补充所涉及的特定资源，这一点仍未得到探索。我们通过在蛋白质和可消化碳水化合物含量不同的饮食方案下，用一种高致病性昆虫病原体（核多角体病毒）对毛虫（草地贪夜蛾）进行实验性挑战，来测试这种可能性。我们发现，与饮食中的碳水化合物相比，饮食中的蛋白质对病原体攻击的抵抗力和组成性免疫功能的影响更大，这表明抵抗的蛋白质成本高于能量成本。此外，当允许昆虫自行选择饮食时，与对照组以及死于感染的幼虫相比，在病毒攻击中存活下来的昆虫增加了它们相对的蛋白质摄入量，从而证明了对与抵抗力相关的蛋白质成本的补偿。这些结果表明，宿主为对抗感染而改变的营养需求会引起进食行为的补偿性转变。
