Seasonal Activity and Foraging Preferences of the Leaf-Cutting Ant Atta sexdens piriventris (Santschi) (Hymenoptera: Formicidae).

Leaf-cutting ants are known for their habit of foraging. These habits can be influenced by several factors, including variations in topography, soil, and climate among others. The objective of this research was to study the seasonal activity and foraging preferences of the leaf-cutting ant Atta sexdens piriventris (Santschi). The study was carried out from January to October of 2007 in grasslands of the state of Santa Catarina, Brazil. Nests of A. sexdens piriventris were randomly selected and the forager's activities were recorded. Damaged plant species, soil fertility, and climatic conditions were recorded. The maximum foraging activity in the summer was recorded during periods of darkness or low light (between 7 p.m. and 5 a.m.). In autumn and spring, foraging was the highest in the morning, but during winter time the foraging activity was high in the afternoon. Fourteen plant species were frequently visited during our study with the lowest foraging activity being recorded at very low (1 to 4°C) or very high temperatures (above 26°C). The number of exploited plant species was higher in winter (13) than in summer (9). Baccharis trimera (Asteraceae) (43%) and Paspalum spp. (Poaceae) (33%) were the most exploited plants among the identified species.