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效率。社会性昆虫的寄生虫不仅可通过调控单个宿主的表型获益，还可通过诱导未感染的群体成员发生变化来达成目的。已知被短体绦虫（Anomotaenia brevis）感染的尼氏扁胸切叶蚁（Temnothorax nylanderi）工蚁，在化学通讯信号特征上与同巢个体存在显著差异，且不会为蚁群适合度做出贡献，但仍会被蚁群容忍并得到良好照料。本研究通过调控受绦虫感染工蚁的存在与否，分析其存在与缺失对同巢个体行为的影响，以此探究受感染工蚁对蚁群攻击性的调控效应。研究结果显示寄生虫诱导了蚁群攻击性的转变：来自受感染蚁群的未感染同巢个体对同种个体的攻击性显著降低，这或可解释蚁群对受感染蚂蚁的容忍机制。本研究同时证实，受绦虫感染的工蚁逃逸反应减弱、存活率提升，而其存在会导致未感染同巢个体的存活率下降。受感染蚂蚁的异常行为与其存活率提升相结合，或可助力寄生虫向终末宿主啄木鸟完成传播。综上，寄生于社会性群体个体的寄生虫，不仅会诱导单个宿主发生表型改变，还会对未感染的群体成员产生影响。