RNA virus spillover through myrmecophilous interactions

Many organisms, especially arthropods, have evolved alongside ants, benefiting from the stable environment, protection from predators, and easy access to food that ant colonies provide. These organisms, known as myrmecophiles, have varying levels of association with ants, ranging from complete dependence to occasional contact or even avoidance. While previous research has shown that ants and their myrmecophiles may share chemical profiles and symbionts, it is unclear if pathogens can be transmitted through such myrmecophilous interactions and what degree of proximity and level of association affect pathogen transmission. In this study, we collected ant nests and their associated arthropods with differing levels of proximity and interaction with ants and then profiled their virus diversity. We focused on two ecologically dominant ant species, the odorous house ant (Tapinoma sessile) and the big-headed ant (Pheidole megacephala) as model systems. We found that arthropods preying or scavenging within ant nests shared RNA viruses with their host colonies, while those residing nearby ant nests did not. These results suggest that close interactions between ants and arthropods form a promising pathway for pathogen transmission that may vary with level of association. This study presents the first case of virus spillover between ants and their myrmecophiles.