Impacto das mudanças climáticas na eficiência de forrageamento de Acromyrmex subterraneus: uma análise comportamental

Abstract

Rising temperatures associated with climate change directly affect ectothermic organisms such as ants, whose locomotion and foraging performance depend strongly on environmental conditions. In Acromyrmex subterraneus, locomotor performance follows a thermal performance curve, reaching maximum values within an optimal temperature range and declining under extreme conditions. In this study, we investigated how warming of the trail surface affects the foraging behavior of A. subterraneus, focusing on both individual- and colony-level parameters. Four colonies were exposed to glass trails under two thermal conditions, heated (~40 °C) and control (~26 °C), with the supply of leaf discs of Acalypha wilkesiana in two sizes (small and large), during 60-minute trials. We evaluated how thermal variation influenced foraging efficiency by analyzing walking speed and locomotor dynamics, worker flow, worker size, and load size selection. Warming of the substrate did not significantly affect the delay to initiate foraging but reduced worker flow by approximately 20% and decreased the proportion of large leaf discs transported (43% on heated trails versus 47% on control trails). In contrast, individual transport efficiency increased by 137% under warming conditions, accompanied by a 126% increase in walking speed. These results indicate that trail warming simultaneously alters multiple components of foraging behavior, revealing a trade-off between walking speed and load size. Understanding such micro-scale thermal effects is essential for predicting how leaf-cutting ants and other ectothermic organisms will respond to environmental change, given that foraging is a fundamental process underlying colony ecology and success.