Selective elimination of microfungi in leaf-cutting ant gardens

Abstract

Leaf-cutting ants encounter many fungi in their environment that may occur as parasites, entomopathogens, saprotrophs, or neutral/beneficial symbionts. The source of these microfungi may be the surrounding soil or the plant material brought to the nest by the ants. Whether the ants' hygienic behavior toward these microfungi is generalized or specific to different fungal species is unknown. We isolated microfungi from leaf-cutting ant gardens and forage material, and then tested the response of the worker ants to these fungal cultures. We found large variation in the rate that ants removed microfungi from their garden chamber. Some strains, including strains of the genera Trichoderma, Escovopsis and Xylaria, were removed at higher rates than others. Our data suggest that the worker ants moderate their behavior in a species-specific rather than generalized fashion when responding to different types of microfungi.