The unique chemical fingerprints of Megalomyrmex: An ant genus of many lifestyles

Julian M. Roberts1, Alissa R. Geisse1, Rachelle M. M. Adams1,2  
1Department of Evolution, Ecology and Organismal Biology Museum of Biological Diversity, Ohio State University, OH, USA. 
2Department of Entomology, Smithsonian Institution, National Museum of Natural History, WA, USA 
The success of eusocial ant societies is attributed to their high level of organization which maintains colony cohesiveness. This cohesiveness is possible due to their ability to recognize nestmates from non-nestmates using colony-specific cuticular hydrocarbons (CHCs). Social parasites (social organisms living at the expense of another) such as Megalomyrmex have evolved mechanisms to bypass this recognition. We compared the CHC and venom alkaloid profiles of four species (M. mondabora, M. cf. wallacei, M. modestus, and M.  foreli) that vary in lifestyle (e.g., generalist predator and social parasite) and other natural history traits (e.g., colony size, queen strategies, etc.). Using gas-chromatography mass-spectrometry, we evaluate the chemical profile (relative abundance and compound presence) of each species as it relates to lifestyle and phylogeny. We discuss how profile differences, visualized with principal component analysis, can be influenced by genetics and the environment. Finally, we consider parasite nest invasion strategies by comparing CHC profiles of a fungus-growing ant host (Cyphomyrmex cornutus) to their social parasite (M. mondabora). This work enhances our understanding of CHC evolution and how it relates to species with varying natural histories.