Data from: Ant societies buffer individual-level effects of parasite infections

Parasites decrease host fitness and can induce changes in host behavior, morphology, and physiology. When parasites exploit social insects, they influence not only infected individuals but the society as a whole. Workers of the ant Temnothorax nylanderi are an intermediate host for the cestode Anomotaenia brevis. We studied a heavily parasitized population and found that while parasite infection had strong and diverse consequences for individual workers, colony fitness remained unchanged. On the individual level, we uncovered differences among the three worker types: infected and healthy workers from parasitized colonies and healthy workers from non-parasitized colonies. Infected workers were smaller than healthy ones and had, as parasite load increased, smaller heads. Behavioral changes extended to all workers from parasitized colonies, which were less active but groomed more. Healthy workers from parasitized colonies showed behavioral patterns intermediate to those of infected workers and healthy workers from non-parasitized colonies. Despite the lower activity level, an important fitness parameter - per-worker productivity - remained unaltered in parasitized colonies. However, the investment strategies of parasitized colonies changed as their sex ratio became male-biased and male body size increased. In short, ant colonies can buffer the drain of resources by the parasite despite strong effects on individual workers.

寄生虫会降低宿主适合度，并可诱导宿主在行为、形态及生理层面发生改变。当寄生虫侵染社会性昆虫时，其影响不仅局限于被感染的个体，更会波及整个蚁群社会。凹唇蚁（Temnothorax nylanderi）的工蚁为异带绦虫（Anomotaenia brevis）的中间宿主。本研究针对一处重度寄生的蚁群种群展开调查，结果发现：尽管寄生虫侵染对工蚁个体产生了强烈且多样的影响，但蚁群整体适合度并未发生改变。在个体层面，本研究揭示了三类工蚁之间的差异：来自寄生蚁群的被感染工蚁、来自寄生蚁群的健康工蚁，以及来自非寄生蚁群的健康工蚁。被感染的工蚁体型小于健康工蚁，且随着寄生虫载量升高，其头部尺寸愈发偏小。行为改变的影响范围覆盖了寄生蚁群中的所有工蚁：这些工蚁活跃度更低，但理毛行为更为频繁。来自寄生蚁群的健康工蚁，其行为模式介于被感染工蚁与来自非寄生蚁群的健康工蚁之间。尽管工蚁活跃度有所下降，但一项关键的适合度参数——单工蚁生产力——在寄生蚁群中并未发生改变。然而，寄生蚁群的资源投入策略发生了改变：其种群性比偏向雄性，且雄性个体体型增大。简言之，尽管寄生虫对工蚁个体产生了强烈影响，但蚁群能够缓冲寄生虫造成的资源损耗。