Individual Flexibility and Tempo in the Ant, Pheidole dentata, the Influence of Group Size

Abstract

This study investigates individual flexibility of foraging ants (Pheidole dentata) when the number of nestmates is altered by establishing broodless and queenless colony fragments all originating from a single big colony. Scouts from small groups (5 to 15 ants) behave like solitary foragers. They feed for long periods of time, they return slowly into the nest, and they recruit weakly. The ingested food is distributed by trophallaxis. Scouts from larger (20- to 30-ant) fragments forage more socially. Feeding and return times are short and recruitment is strong. Later the food is always transported into the nest. Two alternative mechanisms are discussed to explain the differences in individual foraging behavior. For the first—individual flexibility—assumptions have to be made about the capabilities of the individual, its work repertoire, and decision making outside the nest. The second mechanism takes into account that ants are capable of perceiving CO2concentration differences and that ant groups are more active at higher CO2concentrations. The organizational differences at the group level are explained simply by tempo differences in individual ants without making assumptions about individual capabilities.