Behavioral Response of the Leaf-Cutting Ant Atta cephalotes (Hymenoptera: Formicidae) to Trichoderma sp.

Species of the genus Trichoderma sp. are used to control leaf-cutting ants. However, knowledge about the collective immune responses of ants against this antagonist is scarce. Therefore, this study assessed the frequency of hygienic behaviors deployed by medium workers of Atta cephalotes. For this purpose, suspensions of Trichoderma sp. spores were sprayed on sub-colonies composed of workers and a portion of the mutualist. As a control, the sub-colonies were sprayed with water. Independent of whether the workers were treated with spores of Trichoderma sp. or water, they increased the frequency of self-grooming while reducing the frequency of fungus grooming. These findings suggest that medium workers prioritize the removal of contaminants from their bodies over the interaction with the mutualist, possibly to avoid further contamination in the garden. In the field, this strategy may minimize the possibility that foraging ants exposed to contaminants from the exterior can transfer potentially hazardous materials to the nest where they can reach the garden, risking the colony’s productivity.