Data from: Colony pace: a life-history trait affecting social insect epidemiology

Among colonies of social insects, the worker turnover rate (colony ‘pace’) typically shows considerable variation. This has epidemiological consequences for parasites, because in ‘fast-paced’ colonies, with short-lived workers, the time of parasite residence in a given host will be reduced, and further transmission may thus get less likely. Here, we test this idea and ask whether pace is a life-history strategy against infectious parasites. We infected bumblebees (Bombus terrestris) with the infectious gut parasite Crithidia bombi, and experimentally manipulated birth and death rates to mimic slow and fast pace. We found that fewer workers and, importantly, fewer last-generation workers that are responsible for rearing sexuals were infected in colonies with faster pace. This translates into increased fitness in fast-paced colonies, as daughter queens exposed to fewer infected workers in the nest are less likely to become infected themselves, and have a higher chance of founding their own colonies in the next year. High worker turnover rate can thus act as a strategy of defence against a spreading infection in social insect colonies.

在社会性昆虫的蜂群中，工蜂更替率（colony ‘pace’，即蜂群周转速率）通常存在显著差异。这对寄生虫的流行病学传播具有重要影响：在‘快周转’的蜂群中，工蜂寿命较短，寄生虫在单只宿主体内的停留时间会被缩短，进而降低寄生虫的进一步传播概率。本研究对此展开验证，旨在探究蜂群周转速率是否为一种抵御传染性寄生虫的生活史策略。我们以感染性肠道寄生虫熊蜂短膜虫（Crithidia bombi）侵染地熊蜂（Bombus terrestris），并通过实验操控出生率与死亡率，以模拟慢周转与快周转两种蜂群模式。研究结果显示，快周转蜂群中的工蜂感染率更低，尤为关键的是，负责培育生殖型个体的末代工蜂感染率也更低。这一结果可提升快周转蜂群的适合度：因巢内接触受感染工蜂的新蜂王更少，自身感染寄生虫的概率更低，且在次年建立新蜂群的可能性更高。因此，较高的工蜂更替率可作为社会性昆虫蜂群抵御传染性寄生虫扩散的防御策略。