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.

寄生虫可通过诱导宿主表型改变，提升自身的存活能力与传播效率。社会性昆虫的寄生虫不仅可通过调控单个宿主的状态获益，还可通过改变未感染群体成员的状态实现额外收益。已知感染短异带绦虫（Anomotaenia brevis）的尼兰钝切叶蚁（Temnothorax nylanderi）工蚁，其化学信号特征与同巢伙伴存在显著差异，且无法为巢群适合度做出贡献，但仍可被巢群容忍并获得良好照料。本研究通过调控受感染工蚁的存在与否，分析其存在与缺失是否会引发巢友的行为改变，以此探究感染工蚁对巢群攻击行为的影响。研究结果显示，寄生虫诱导了巢群攻击行为的转变：来自受感染巢群的未感染巢友，对同种个体的攻击性显著降低，这或可解释巢群对受感染蚂蚁的容忍机制。此外，本研究证实，受绦虫感染的工蚁逃逸反应减弱、存活率更高，但其存在会导致未感染巢友的存活率下降。受感染个体的异常行为与其存活率提升相结合，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，还可对未感染的群体成员产生影响。