Life span of queens in the antFormica exsecta

Abstract

The antFormica exsecta commonly has two types of colonies: either polygynous and polydomous or monogynous and monodomous. The longevity of queens was studied in monogynous colonies in southern Finland by indirect methods using genetic markers; these data were also used to estimate the number of matings and queen replacement. The average genetic relatedness among worker nest mates was 0.72. Taking inbreeding into account (the inbreeding coefficient wasF=0.16), this value agrees with the assumption that 40% of the queens mated with one male and 60% with two males. The distribution of genotypes within colonies remained stable in successive years, indicating that queen replacement did not occur or was extremely rare. This means that the life span of nests reflects directly the life span of the queens. Eleven of the 16 nests found in 1979 were still alive ten years later. This corresponds to an annual mortality of 3.7% and a mean life span of 27 years. A total of 57 colonies were mapped in the population over a period of ten years. Averaging over the years, the annual mortality was estimated to be 4.9%. This represents a mean life span of 20 years if mortality was independent of age.