The results show how social immunity provided by the
altruistic provision of antimicrobial secretions from adult ants
has evolved to play an important role in brood survival and
maintaining hygienic nest conditions and, thus, the fitness of
their colony. In addition, we show that these social secretions
are important, not just to combat specialist parasites like
Metarhizium and Escovopsis but also in the everyday defense
against opportunistic microbes which are ubiquitous in and
around nest sites. This not only highlights the vulnerability of
brood and nest material to disease but also their reliance on
social care and provides a compelling explanation for how
immobile brood with immature immunity survives in a world
abundant with pathogens.