Colonies of social insects, similar to individual animals, attempt to maximize the profitability of the resources they exploit. But how best to choose the most profitable resource – especially when presented with multiple options? One potential strategy would be for individuals to sample several options and make a direct comparison before choosing a resource to exploit or recruit to. Another option would be to rely upon a collective framework for choice – where group choice emerges independently of individual assessment. In this study, we attempt to answer this question in the context of ant colony foraging: How are scout ants informed of the quality of the food resource or resources they encounter? For our model organism we used the ant species, Temnothorax rugatulus, which has become a model organism for studies of insect collective behavior. We found that while many ants (both foragers and receivers) had the opportunity to make direct comparisons, they did not act on this information to alter the colony foraging response. Instead, foragers relied upon their own sensory thresholds and assessment of profitability (which included not only the concentration of sucrose but also the travel cost to a given feeder). When colonies were presented with feeders of equal quality at two different distances (near and far), ants recruited at a higher rate to the near feeder. These results support the view that small societies of social insects likely rely on the same emergent framework for collective choice as large societies such as honeybees.
