COLONY FOUNDATION AND POLYGYNY IN THE ANT FORMICA-PODZOLICA

We document the variation in number of queens occurring naturally in f ounding, immature and mature nests of the ant Formica podzolica, and c ompare development of colonies and survivorship of queens in experimen tal nests started with 1-16 foundresses. Number of queens per nest was associated with stage of colony development. Most nests were monogyno us, but 20% of immature nests (n = 66) and 25% of mature nests (n = 99 ) were oligogynous or polygynous. Colonies were usually established by single queens (i.e., haplometrosis), but colony establishment by mult iple queens (i.e., pleometrosis) was also common, occurring in 27% of founding nests (n = 492). Foundress groups in the field were small ((x ) over bar = 1.47 +/- 0.04 queens/nest), and large groups experienced high mortality and low productivity in artificial nests. Therefore, th e many queens (up to 140) in some immature and mature colonies were pr obably secondarily pleometrotic. Experimental nests started with 1-4 q ueens were more successful than those initiated by 8 or 16 queens. Sma ll groups (2-4 queens) produced more pupae before the first nests rear ed workers than single foundresses or larger groups (8 or 16 queens). Although single foundresses were less productive than queens in small groups, they experienced greater survivorship and less weight loss tha n queens in pleometrotic associations. Besides low productivity, queen mortality and weight loss were greatest in large groups.