Data from: Host-associated beneficial gut microbiota boosts induced immunity and limits immune deployment costs in bumblebees

Ecological immunology posits that variation in host resistance to
infection may be attributed partly to the ecological and evolutionary
costs of immunity. While the deployment of immune defense is necessary to
combat pathogenic infection, host pay energetic and other costs for
activation. Host-associated beneficial microbiota have been shown to
affect multiple host traits, including immunity, but how interactions with
these microbial communities may mitigate the costs of immune activation
remains an open question. For apid bees, including eusocial bumblebees,
core members of the adult gut microbiota contribute to a variety of
fitness-relevant traits and provide a key ecological and evolutionary
relationship contributing to ecological success. Here, we test the
hypothesis that the host-associated microbiota provides benefits to bumble
bee immunity, including the mitigation of the costs associated with
inducible immune responses. Freshly emerged germ-free adult workers were
supplemented with their native microbiota via experimental fecal
transplants from nestmates or kept deprived of their native microbiota
inoculum. We assessed functional measures of induced immunity and assessed
the costs of non-pathogenic immune activation for survival. In support of
our hypothesis, we find that microbiota supplementation strengthened
functional antibacterial immunity. Moreover, although we observed a cost
of immune activation for survival, the cost was much greater for bees
deprived of their native gut microbiota compared to those supplemented.
Thus, we provide evidence that in addition to other roles, the microbiota
mitigates costs of immune deployment. This demonstrates a key role for
host-associated microbiota in the realization of induced immune defense,
and contributes more broadly to our understanding of microbiota-immune
interactions in the context of ecological immunology.