The ant social parasite Protomognathus americanus and its effect on foraging rates of its host species, Temnothorax longispinosus

In parasite-host interactions, the host is a part of the extended phenotype of the parasite and thus acts, often to its own detriment, in such a way that increases the parasite’s fitness. This study examines how the obligate slave-making parasite Protomognathus americanus increases the foraging rate of its host, Temnothorax longispinosus. We have previously found that the odds of a host worker in a parasite colony foraging for food are twice as great as the odds of a conspecific worker doing so while living in a colony without the parasite, regardless of colony size. Presently, we consider the effect that removing the parasite from a colony has on host foraging, both in the number of foragers and the amount of food brought back to the nest. We not only determine the foraging rate of the host after the total removal of the parasite from the nest but also after separating the parasite from the host with a layer of woven stainless mesh. In this way we can determine if the parasite is inducing increased foraging through physical interactions with the host workers, either through increased trophallaxis or increased aggression, or by more indirect means, such as through a pheromone or vibrational signaling. We hope to further explore the behavioral ecology and coevolutionary arms race present in this social parasite system.