Ecology, behavior and natural history of Poneroide and Ectatomminoide ants in the Neotropical cerrado savanna

Poneroide and Ectatomminoide ants show the highest diversity of habits among members of the family Formicidae. Because ants in these two groups are involved in various types of interspecific interactions, they frequently act as regulators of arthropod populations, seed dispersers, and promoters of physical changes in the environment. Given the relevant ecological roles these ants play in the cerrado savanna, we carried out a natural history account of selected ants in these two groups, including their feeding habits, foraging strategies, activity schedules, types of interactions, and demography. In a cerrado reserve in southeast Brazil, we tagged 93 nests of four most common species: Odontomachus chelifer, Pachycondyla striata, Ectatomma edentatum, and E. permagnum. General nest distribution was random, although some species tended to an aggregated spatial pattern (P. striata and E. edentatum). All species forage within a preferred time schedule over 24 hours. The activity peaks of the four species do not overlap in time, suggesting a temporal partition of food resources. Ectatomma edentatum had the smallest home range (1.54 m²) and E. permagnum the larger (8.06 m²). Termites were the main food item in the diet of the four species, although ants were also seen carrying parts of other insects as well as fleshy seeds and fruits. Ecological and natural history accounts of ants are crucial in the Neotropics, where data on basic ecological features of most species are lacking. This is especially notable for the ant-rich cerrado savanna, currently under serious threat by human action (FAPESP, CNPq).