Um passo de cada vez: como a temperatura da trilha afeta o deslocamento de operárias forrageiras de Acromyrmex subterraneus (Hymenoptera, Formicidae)

Abstract

Acromyrmex subterraneus is a Neotropical ant species whose behavior is strongly influenced by environmental conditions. In the context of climate change, characterized by episodes of pronounced temperature increases, these individuals must adjust their locomotor behavior to trail warming in order to maintain the colony’s resource supply. Increased substrate temperature can alter locomotor biomechanics, leading to a reduction in the duration of the stance and swing phases of the stride, as well as to changes in gait pattern, with the replacement of the alternating tripod gait by polygonal and polygonal-with-drag gaits. In this study, four colonies were subjected to glass trails under two conditions, heated (~40 °C) and control (~26 °C), with the offer of leaf discs of Acalypha wilkesiana in two sizes (small and large), in 60-minute trials. We evaluated how thermal variation interferes with the displacement dynamics of workers of different sizes and carrying loads, gait style, and the duration of stance and swing phases. The results showed that stride length decreased more markedly in larger workers (up to 8.83%). Both stance and swing phases were shortened, indicating faster strides with reduced amplitude. The tripod gait was not observed; only polygonal and polygonal-with-drag gaits occurred, the latter being more frequent on heated trails. These findings suggest that trail warming affects ant locomotor biomechanics, revealing a sophisticated mechanism of adaptability to different climatic adversities. Understanding these effects is essential to predict how leaf-cutting ants and other ectothermic organisms will respond to environmental changes, given that locomotor performance and foraging are fundamental processes for colony ecology and success.