Bacterial symbiont sharing in Megalomyrmex social parasites and their fungus-growing ant hosts

Bacterial symbionts are important fitness determinants of insects. Some hosts have independently acquired taxonomically related microbes to meet similar challenges, but whether distantly related hosts that live in tight symbiosis can maintain similar microbial communities has not been investigated. Varying degrees of nest sharing between Megalomyrmex social parasites (Solenopsidini) and their fungus-growing ant hosts (Attini) from the genera Cyphomyrmex, Trachymyrmex and Sericomyrmex allowed us to address this question, as both ant lineages rely on the same fungal diet, interact in varying intensities and are distantly related. We used tag-encoded FLX 454 pyrosequencing and diagnostic PCR to map bacterial symbiont diversity across the Megalomyrmex phylogenetic tree, which also contains free-living generalist predators. We show that social parasites and hosts share a subset of bacterial symbionts, primarily consisting of Entomoplasmatales, Bartonellaceae, Acinetobacter, Wolbachia and Pse...