Endophytic fungi increase the processing rate of leaves by leafcutting ants (Atta)

1. Fungal endophytes are microfungi that reside asymptomatically inside of leaf tissues, increasing in density and diversity through time after leaves flush. Previous studies have suggested that the presence of fungal endophytes in the harvest material of leaf-cutting ants (Atta colombica, Guérin-Méneville) may negatively affect the ants and their fungal cultivar. 2. In the present study, it was tested whether the presence and diversity of fungal endophytes affected the amount of time necessary for leaf-cutter ants to cut, process, and plant leaf material in their fungal garden. It was found that ants took 30–43% longer to cut, carry, clean, and plant leaf tissue with high relative to low endophyte abundance, and that the ants responded similarly to leaf tissue with high or low endophyte diversity. 3. It was further investigated whether the fungal cultivars’ colonisation rate was greater on leaf material without fungal endophytes. No difference in the ants’ cultivar colonisation rate on leaf tissue with high or low endophyte abundance was observed.