Nest Recognition in the Ant, Leptothorax ambiguus Emery (Hymenoptera: Formicidae)

Leptothorax ambiguus Emery is a species of minute ants. In southern Ontario, colonies most frequently nest in old Quercus alba and Q. rubra acorns and in Carya ovata and C. cordiformis hickory nuts, which beetle larvae (especially Curculionidae) and other insects have partly hollowed out before the ants move in. L. ambiguus colonies frequently contain several functional queens (polygyny) and often occupy several acorn nests (polydomy). A 'typical' large colony would occupy 2 or 3 acorn nests and consist of 3 or 4 queens, 75 to 100 workers, and a brood of eggs, larvae, and pupae (Alloway et al. 1982). L. ambiguus colonies defend the area around their nests against incursions by workers from other L. ambiguus colonies and from colonies of two closely related species, L. curvispinosus Mayr and L. longispinosus Roger. During territorial battles, workers bite and sting their adversaries and employ tandem running (Moglich et al, 1974) to recruit nestmates to places where workers from the other colony have been encountered (Alloway 1980). The co-occurrence of territoriality and polydomy and the fact that L. ambiguus colonies are sometimes raided by the slave-making parasites Leptothorax duloticus Wesson or Protomognathus americanus (Emery) led us to wonder whether L. ambiguus colonies possess the capacity to discriminate between one of their own nests and a nest belonging to another L. ambiguus colony. Such an ability should be useful if part of a polydomous colony had to evacuate a nest in which they had been living and emigrate to one of their colony's other nests as a consequence of either a territorial fight, a slave raid, or structural damage to their acorn nest.