Microfungi in the fungus gardens of the leaf-cutting ant Atta cephalotes: a preliminary study

Eighteen taxa and a number of sterile mycelia and yeasts were isolated from three fungus gardens of Atta cephalotes of which most reflected the endophytic and epiphytic fungal biota of the leaves of their food plants. The colonization frequency by Leucoagaricus gongylophorus varied from 72 to 95% depending on the food plants available to the ants and on whether the fungus gardens were sampled from a nest in the field or the laboratory. Infections per leaf unit which made up the fungus gardens varied from 1.31 to 1.63. A change in diet for one of the fungus gardens was accompanied by a significant reduction of filamentous fungi recorded from the nest. Comparisons of the incidence of the filamentous microfungi other than L. gongylophorus between the upper and lower portions of each nest and between colonies reveal significant heterogeneity. From 20 to 40% of leaf fragment from the colonies showed the presence of yeasts. The significance of the fungus garden on the health of the ant colony and the ultimate fate of microfungal invaders are briefly discussed.