A carbohydrate-rich diet increases social immunity in ants

Increased potential for disease transmission among nest-mates means living in groups has inherent costs. This increased potential is predicted to select for disease resistance mechanisms that are enhanced by cooperative exchanges among group members, a phenomenon known as social immunity. One potential mediator of social immunity is diet nutritional balance because traits underlying immunity can require different nutritional mixtures. Here, we show how dietary protein–carbohydrate balance affects social immunity in ants. When challenged with a parasitic fungus Metarhizium anisopliae, workers reared on a high-carbohydrate diet survived approximately 2.8× longer in worker groups than in solitary conditions, whereas workers reared on an isocaloric, high-protein diet survived only approximately 1.3× longer in worker groups versus solitary conditions. Nutrition had little effect on social grooming, a potential mechanism for social immunity. However, experimentally blocking metapleural glands...群居生活存在固有代价，其根源在于同巢个体间的疾病传播风险升高。这种升高的传播风险经预测会推动自然选择青睐于演化出依赖群体成员协作交换的疾病抵抗机制，这一现象被称为社会免疫（social immunity）。饮食营养平衡是社会免疫的潜在调控因子之一，因为免疫相关性状的实现往往需要特定的营养组合。本研究揭示了饮食蛋白质-碳水化合物平衡如何影响蚂蚁的社会免疫：当被寄生真菌绿僵菌（Metarhizium anisopliae）侵染时，饲喂高碳水化合物日粮的工蚁，在群体饲养条件下的存活时长约为单独饲养时的2.8倍；而饲喂等热量高蛋白日粮的工蚁，在群体饲养条件下的存活时长仅约为单独饲养时的1.3倍。营养水平对社会梳理——社会免疫的潜在机制之一——几乎无影响。然而，当通过实验阻断后胸腺（metapleural glands）时……