干旱区生态环境知识资源中心

The temporal dynamics of foraging, diet, and use of space is essential to understand the ecology of harvester ants. Here, we present an account of the foraging ecology of Pogonomyrmex naegelii in Brazilian cerrado savanna. Nests occur on bare ground and contain 166-580 workers (N = 3 colonies). Colony activity is unimodal year-round and peaks around the middle of the day. Foragers leave the nest independently and individually search for food in all directions. Ants ventured up to 15 m from nests, with most foraging occurring within 2 m of nests. Colonies tended to have larger home ranges in the dry/cold (April-September) than in the wet/warm season (October-March). P. naegelii has a generalist and season-dependent diet comprised of many seed species and arthropod prey, and pieces of plant and animal matter. Foragers collected seeds from 34 plant species, predominantly grasses (genera Gymnopogon, Axonopus, Aristida). Over 6,700 seeds can be stored in nest granaries. Ants and termites were the main animal prey retrieved by P. naegelii. The proportion of seeds and arthropods foraged by P. naegelii changes year-round: in the dry/cold season, the diet is predominantly granivorous, whereas in the wet/warm season, seeds and arthropods are retrieved in more balanced proportions. Although food availability was not assessed, year-round diet of P. naegelii matches the pattern of seasonal abundance of grass seeds and arthropod prey in cerrado. Data on harvester ants come mostly from arid habitats; this study is a first assessment of the ecology of a Neotropical Pogonomyrmex from a moderately moist savanna environment.