Asymmetrical Use of Appendages in Food Probing by Two Ant Species

Lateralization, or the presence of left–right asymmetry, is a widespread phenomenon in vertebrates and has been shown to confer various adaptive advantages, as lateralized individuals tend to outperform non-lateralized ones in specific tasks. In contrast, much less is known about lateralization in invertebrates. Further investigation into lateralization in understudied invertebrate groups is crucial for deepening our understanding of its evolutionary origins. In this study, we evaluated asymmetries during food probing behaviors in two ant species, Lasius niger and Linepithema humile. Overall, both species exhibited asymmetries, favoring either a particular leg or antenna when investigating a sugar drop. Interestingly, L. niger favored the right side, while L. humile favored their left. These results imply the absence of a strong driver for a bias on a specific side preference for food probing in ants, but a potential benefit of lateralization in food probing. Supporting this, individuals fully lateralized on the opposite side of the majority were observed in both species. The collective bias found in both species supports the theory that population-level lateralization may have evolved in species that need to coordinate their behaviors. This study provides novel insights into the lateralization of ant behaviors and highlights the need for further research into its evolutionary drivers.