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.