Experiments on colony foundation in the slave-making ant Harpagoxenus canadensis M. R. Smith (Hymenoptera; Formicidae)

Abstract

Queens of obligatory socially parasitic ants are unable to found colonies independently and typically initiate new colonies by invading host-species nests and usurping the role of reproductive. In some cases, fission ("budding") of parasite colonies also occurs. This study is the first to investigate colony foundation in the obligatory slave-making ant Harpagoxenus canadensis M. R. Smith. Laboratory experiments examined whether colonies could be founded (i) independently by a parasite queen, (ii) jointly by a parasite queen and a host queen, (iii) by budding, and (iv) by usurpation. Parallel experiments using host-species queens (Leptothorax sp.) were conducted for independent colony foundation and joint colony foundation by two conspecific queens. The results indicate that parasite queens found colonies by usurpation. Parasites invaded host nests using either an "active" aggressive strategy or a relatively less aggressive "passive" strategy, obtained host brood, and were occasionally adopted by a large portion of the host colonies' adults. Host-species queens successfully founded colonies both independently and jointly.