Influência de variáveis ambientais na distribuição espacial de espécies de formigas cortadeiras (Hymenoptera: Formicidae) em eucaliptais cultivados no Bioma Pampa

Abstract

Eucalyptus is the most important crop for the forest sector in Brasil, but has problems with pest attack, especially leaf-cutting ants of the genera Atta and Acromyrmex, considered key pests of this crop. These insects occur in all Brazilian states, however, not clear which and how many species of these ants are associated with the eucalyptus cultivation, or how environmental factors influence or limit the occurrence or distribution of these species in certain regions. This study aimed to examine patterns of distribution, density and frequency of leaf-cutting ant species and evaluate the influence of environmental variables (canopy cover, soil clay content and altitude) on the population density of these ants in eucalyptus plantations at Pampa biome. Then, this study was carried out in eucalyptus plantations in order to obtain the geographic location of the nests of ants and species identification, and collection of environmental variables mentioned. We identified seven species of leaf-cutting ants associated with eucalyptus crop. Atta sexdens was the most frequent and abundant. The predominant spatial distribution was aggregated, but it varied with ant species and the clay content of the soil. Clay content of the soil influences negatively the population density of the species, while canopy cover and altitude, positively.