Landscape configuration modulates the presence of leaf-cutting ants in eucalypt plantations

Abstract Leaf-cutting ants (LCAs) are herbivorous insects endemic to the Neotropical region that cause considerable problems in agricultural and forestry production. In particular, LCAs are a major threat for non-native forest plantations in tropical and subtropical Americas. Here we evaluate the presence and abundance of LCA nests in different spatial contexts associated with young Eucalyptus plantations in the littoral region of Argentina: land uses, interfaces (pairs of neighboring land uses), agroecosystems and landscapes. We selected 30 sites representing 3 types of land uses neighboring Eucalyptus plantations: adult eucalypt plantations, citrus plantations and semi-natural habitats. At each site, we quantified and identified LCA nests on two transects (50x4 m) during the fall of 2022. In addition, we quantified landscape composition and configuration in circular landscapes of 250m radius. We found that LCA nests abundance and presence was similar across different land uses, interfaces, and agroecosystems, although semi-natural land uses and the plantation forest agroecosystem tend to have more nests. Nest presence decreased in landscapes with increasing mean perimeter/area ratio and LCAs abundance showed a similar trend, meaning that small-grain landscapes were less likely to have LCA nests. Despite that LCAs seem to be resistant to human disturbance, our results suggest that decreasing patch size within productive landscapes by planting small plots of trees surrounded by other habitats could be the simplest way to decrease damage by LCAs. Understanding the dynamics of ant populations and their complex associations with landscape components will help promoting a successful environmental management plan for eucalypts forest plantations.