LB 3-24 - Colony size and food source abundance affect food source selection in a model of ant foraging

Many ant species use pheromones to mark trails to sources of food. The strength and persistence of these trails depends both on the quality of and the distance to a given food source, determining how an ant colony allocates foraging effort among different food sources. The objective of this research is to understand how ant colonies navigate the potential tradeoff between exploiting nearby, poor-quality resources and far away, high-quality resources. Previous work shows that a differential equation model of the number of ants on trails to different food sources can accurately describe the dynamics of trail formation and food source selection. Using numerical integration, we utilize this model to examine how changing the number of ants available to forage and the number of potential food sources affects the quality-distance tradeoff. Here we show that the model leads to most ants visiting either the nearest food source or the source with the highest quality-to-distance ratio, depending on the parameters. Our results predict that larger ant colonies will typically prioritize food sources with high quality-to-distance ratios while smaller colonies tend to favor closer food sources. When colony size is held constant, environments with more potential food sources will lead colonies to favor sources with high quality-to-distance-ratios whereas colonies in environments with fewer food sources will favor closer food sources. In conclusion, our research suggests that, compared to small colonies, larger colonies may be better able to find and exploit high-quality resources, particularly when resources are sparse.