Interações competitivas no forrageamento entre Atta laevigata e Atta sexdens (Hymenoptera: Formicidae)

Abstract

Competition for resources between leaf-cutting ants, such as Atta laevigata and Atta sexdens, can modulate foraging behavior and influence aggressive interactions among colonies. Understanding these patterns is important for colony management in plantations, as differences in competitive performance between species may affect the effectiveness of baits used for pest control. In this study, we investigated resource competition between A. laevigata and A. sexdens under both field and laboratory conditions. In eucalyptus plantations, we assessed foraging frequency on artificial baits placed between 90 interspecific pairs of colonies. Atta sexdens exhibited higher foraging frequency regardless of nest size; however, this advantage decreased when resources were located close to A. laevigata nests. Foraging activity was higher during the dry season and was strongly influenced by resource proximity to the nest, highlighting the importance of spatial and seasonal factors. Under laboratory conditions, we tested the effects of temperature, prior territory marking, and direct confrontation between colonies. Atta laevigata showed greater recruitment efficiency than A. sexdens, although both species exhibited reduced activity at extreme temperatures. Neither the latency to enter the arena nor the onset of resource retrieval was affected by any tested factor, indicating conserved behavioral responses. The occurrence of workers returning without loads was influenced by temperature and the presence of competition. Aggressive interactions increased in arenas previously marked by A. sexdens and under direct confrontation, whereas no significant differences were detected between species in the number of aggressive acts, suggesting equivalent potential to sustain conflicts modulated by environmental factors. Overall, our results indicate that the coexistence of these species is mediated by spatial, seasonal, and thermal niche partitioning, reflecting competitive asymmetries shaped by temperature, seasonality, spatial arrangement, and territory marking. From a pest management perspective, bait-based control strategies should consider species identity, time of year, colony proximity, and local thermal conditions to enhance control effectiveness in forest plantations.