Selective foraging by Acromyrmex spp. ants in grassland ecosystems of Lages, Brazil, impacts biodiversity and plant resources

This study investigated the foraging behavior of ants of the genus Acromyrmex spp. in high-altitude natural grasslands in the microregion of Lages, Brazil. Fifty-nine anthills were sampled, identified by the presence of ants in trails or by direct observation of the nests, which present a characteristic mixture of soil and straw on the surface. Each anthill was georeferenced, and two active trails per nest were chosen for collection of foraged material. The collection occurred within a radius of 20 meters around the trails, focusing on plants with ants in foraging activity. These plant samples were herborized and classified in the laboratory. In total, 72 plant species were identified, distributed in 26 botanical families. The families Poaceae and Asteraceae presented the largest number of foraged species. In terms of foraging frequency, the families Poaceae (109 species), Fabaceae (28 species) and Asteraceae (25 species) stood out. The most foraged plants were Trifolium pratense (Fabaceae) and Paspalum spp. (Poaceae). Most anthills were located on the edges of forest fragments. The study contributes to the understanding of the relationship between Acromyrmex spp. and local vegetation, providing relevant data on the interaction of these insects with the environment.