Ants and aphids are involved in a mutualistic relationship whereby the aphids produce a sugary waste product which the ants then harvest as food. We were interested in exploring the dynamics of this relationship, and specifically how ant movement was influenced by the distribution of aphids and the distribution of members of their own species. For this study, we focused on the interactions between the two insects on the flowering racemes of yucca glauca in the Rocky Mountains region. Ant populations showed patterns of both single and double attractors, with the number of attractors likely driven by aphid number (we did not have sufficient data to confirm this statistically). Although aphids proved to be a factor in determining the number of attractors, they were not significant in determining the number of ants on a plant or the number of ants entering or exiting that plant. Playing a much larger role in determining arrivals and departures was the number of focal ants, with increased numbers of focal ants lead to increased numbers of arrivals and departures from the plant. The number of ants on the nearest neighbor also impacted ant movement, but it influenced only arrival rates and not departure rates. The degree to which neighboring plants showed similar dynamics varied greatly between plants, but there were certain plants which correlated to a particularly great degree with their neighbors. These plants tended to be those with the most aphids.
Includes bibliographical references