Data from: The parasite’s long arm: a tapeworm parasite induces behavioural changes in uninfected group members of its social host

Parasites can induce alterations in host phenotypes in order to enhance their own survival and transmission. Parasites of social insects might not only benefit from altering their individual hosts, but also from inducing changes in uninfected group members. Temnothorax nylanderi ant workers infected with the tapeworm Anomotaenia brevis are known to be chemically distinct from nestmates and do not contribute to colony fitness, but are tolerated in their colonies and well cared-for. Here, we investigated how infected workers affect colony aggression by manipulating the presence of tapeworm-infected workers and analysing whether their absence or presence resulted in behavioural alterations in their nestmates. We report a parasite-induced shift in colony aggression, shown by lower aggression of uninfected nestmates from parasitized colonies towards conspecifics, potentially explaining the tolerance towards infected ants. We also demonstrate that tapeworm-infected workers showed a reduced flight response and higher survival, while their presence caused a decrease in survival of uninfected nestmates. This anomalous behaviour within infected ants, coupled with their increased survival, could facilitate the parasites’ transmission to its definitive hosts, woodpeckers. We conclude that parasites exploiting individuals that are part of a society not only induce phenotypic changes within their individual hosts, but in uninfected group members as well.

寄生虫可诱导宿主表型发生改变，以提升自身的生存与传播能力。社会性昆虫的寄生虫不仅可通过改变单个宿主的状态获益，还可通过调控未受感染的群体成员实现额外收益。已知感染短节异形绦虫（Anomotaenia brevis）的尼氏细胸蚁（Temnothorax nylanderi）工蚁，其体表化学信号与同巢同伴存在显著差异，且不参与蚁群的适合度贡献，但仍会被蚁群容忍并获得良好照料。本研究通过人为调控受绦虫感染的工蚁的存在与否，分析其存在或缺失对同巢同伴行为的影响，以此探究感染工蚁对蚁群攻击行为的调控作用。本研究发现寄生虫可诱导蚁群攻击行为发生改变：感染蚁群中的未受感染同伴对同种个体的攻击性显著降低，这或可解释蚁群对感染工蚁的容忍机制。此外，本研究证实感染绦虫的工蚁其逃逸反应减弱、存活率提升，而它们的存在会导致同巢未受感染同伴的存活率下降。感染工蚁的异常行为与其存活率提升相结合，可促进该寄生虫向终末宿主啄木鸟的传播。综上，寄生于社会性昆虫个体的寄生虫，不仅可诱导单个宿主的表型改变，还可对未受感染的群体成员产生影响。