Mutualism between Homoptera Aphididae and Hymenoptera Formicae in the presence of predators as observed in Cheboygan County of northern lower Michigan.

Abstract

Mutualism is defined as an interaction between two species in which both benefit from the association. Hymenoptera Formicae and Homoptera Aphididae, have what many ecologists believe to be a mutualistic interaction. Ants tend aphid colonies by patrolling the colonies for hours at a time and driving off predators. The aphids are then able to excrete honeydew as nourishment for the ants while having a reduced probability of predation by intruders. Data was collected on the University of Michigan Biological Station property in northern lower Michigan to record attendance of ants to aphids in the presence of the predators Hippodamia convergens and Chrysoperia carnea on saplings of Populus grandidentata. Probabilities calculated showed that aphids were eaten more frequently in the absence of ants and C. carnea ate aphids more often and faster than H. convergens. Both predators were regularly removed or attacked with ants attendant. However, C. carnea was removed more often than H. convergens, but in the same amount of time. A Mann-Whitney U test demonstrated that high and low ant attendance was only found to be statistically significant for the removal of H. convergens, but not for C. carnea. A higher ant attendance resulted in a faster removal of H. convergens. Ants were found tending aphids alone more often than both ants and female aphids attending aphid colonies, suggesting a ""nanny"" behavior. These observations provided support to conclude that both ants and aphids were mutually profiting from each others' presence.