Spontaneous Polydomy in Laboratory Colonies of the Ant Leptothorax Curvispinosus Mayr (Hymenoptera; Formicidae)

Leptothorax curvispinosus Mayr is a small, common ant in eastern North America where it often nests in such preformed cavities as hollow acorns, hickory nuts, galls, stems and twigs. Its range and nesting preferences overlap broadly with those of two closelyrelated species, L. ambiguus and L. Iongispinosus (Creighton 1950; Alloway et al. 1982). Colonies within this group are both intraand interspecifically aggressive; and although normally considered nonparasitic, they occasionally engage in facultative interspecific slavery, apparently by capturing and rearing brood from one another’s colonies. Facultative intraspecific slavery may occur more frequently (Alloway 1980). In addition, these species serve as hosts for the obligatory slave-makers Harpagoxenus americanus and L. duloticus (Alloway 1979; for terminology see Stuart and Alloway 1983). All five species coexist in some areas, nest in close proximity to one another, and form dense local populations (Alloway et al. 1982; Del Rio Pesado and Alloway 1983). Approximately one third (,36.3%) of individual L. curvispinosus nests (e.g. single acorns) are queenless, while about half (46.7%) are monogynous, and the remainder (17.0%) are polygynous (Headley 1943; Talbot 1957; Alloway et al. 1982). Dissections have shown that polygyny in this species is more than just a superficial phenomenon with over 90% of the queens in polygynous nests being inseminated and reproductive. Moreover, young queens often coexist with older queens, indicating that established colonies may