Foraging ecology of attine ants in a Neotropical savanna: seasonal use of fungal substrate in the cerrado vegetation of Brazil

In this study we identified the material collected as fungal substrate by attine ants in the cerrado vegetation of Southeast Brazil. A total of 313 colonies of the evolutionary more primitive (genera Cyphomyrmex, Mycetarotes, Mycocepurus, Myrmicocrypta) and transitional attines (genera Sericomyrmex and Trachymyrmex) were marked in the field and monitored monthly, during one year. Attines collected material from 53 plant species in 28 families. Items included leaves, flowers, fruits, seeds, wood, mosses, lichens, insect feces and corpses. Flowers and fruits wen the items most frequently collected by all genera, especially during the wet season when these plant parts are more abundant in the cerrado. During the dry season, the ants diversified the material collected and the frequency of different items varied across the ant genera. The most primitive genera collected mainly insect feces and corpses, while the intermediate ones relied on vegetative plant parts such as recently fallen leaflets. Seeds and other materials such as mosses, lichens, and wood were also more commonly used during dry months. The use of these resources was associated with greater foraging distances by all genera in dry months. The results indicate that lower attines present an opportunistic foraging behavior, by collecting items in the vicinity of their nests, and in accordance with the phenology of the cerrado vegetation. We briefly discuss some general evolutionary trends within the Attini.