The wisdom of the acorn: Social foraging of the ant, Temnothorax rugatulus.

Social insect collective foraging epitomizes the concept of emergence.  From the interactions of individuals a group outcome emerges (such as the collective choice of a food source).   But how do they do it?  Ants in the genus Temnothorax provide an excellent model for such questions with their small colony size, interesting recruitment behavior, and experimental tractability.  Using sugar water as a foraging source we can study both group and individual behavior.  By paint marking ants and filming at nest and feeder, we can dissect this process.  Colonies are able to allocate more foragers to better feeders and re-allocate when resources change in quality.  Analysis of individual behavior suggests that quality-dependent recruitment and attrition are the key features allowing the colony to make a ‘choice’.  Recruiting foragers prioritize information dissemination by leading tandem runs without fully offloading nectar.  As with honeybees, receiver ants do not favor foragers with better nectar, and increased search time for receivers correlates with a reduction in recruitment.  While Temnothorax social foraging may be in most respects an emergent process, it is possible that individual scouts make direct comparisons between resources and this may influence the foraging process.