Evolution of surface-borne vibrational communication in fungus-growing ant societies

Abstract

Abstract In ants, chemical communication, through pheromones for example, was thought to be the main communication tool in ant societies; however, a major question is whether chemical substances alone can control highly differentiated social behaviours. In this study, we focused on the surface-borne vibrational signals of fungus-growing ants, key organisms in the Neotropical ecosystem, and conducted a detailed analysis of the signals. Our results indicate that in fungus-growing ants, vibrational communication is a much more frequent and critical factor than previously believed. The frequency of vibrational signal recordings from the ants were found to be significantly correlated with social structure complexity. Structural analysis indicated that both the area and number of slits in the stridulatory organs were significantly correlated with body size. The ability of leaf-cutting ants to maintain fungus gardens was significantly lower in the vibration-inhibited group than in the pheromone secretion-inhibited group. These results suggest that ants that have become more communicative may induce altruistic behaviours and create more complex societies. The findings of this study may be applicable not only to social evolution studies but also for effectively controlling ant behaviours.