Plant, ants and herbivores: untangling the complexities of ant attraction in non-myrmecophilous plants

Scientific literature is replete with examples of both ant-plant mutualisms and responses of predatory hymenoptera to herbivore induced plant volatiles, yet no studies to date have examined the role of ants responding to such volatile emissions. The red imported fire ant, Solenopsis invicta, was recently reported to have more olfactory receptors than any known organism. With this amazing “nose”, it is likely that ants can key into plant-produced cries for help when searching for prey. In this study I examine the ability of the red imported fire ant to discern between herbivore infested and naïve plants both in lab and field conditions. Ants were significantly more likely to forage on plants that had experienced previous mechanical damage than naïve plants and plants where herbivores had fed but were no longer present. Similarly, exogenously applied jasmonic acid, which induces plant defenses against herbivory, greatly increased the number of ants found on plants. This data strongly suggests that ants are in constant communication with the plants around them, listening for cries for help in order to more easily find tasty treats feeding in the canopy.