Queen reproduction, chemical signalling and worker behaviour in polygyne colonies of the ant Formica fusca

Potential reproductive conflicts are common in social insects and may occur between and within castes. In multiqueen (polygyne) colonies of ants, reproductive conflicts among coexisting queens may be resolved by aggressive interactions and/or by pheromonal signalling. Pheromonal signals may be directed at workers, which may adjust the reproductive shares of queens behaviourally. Workers are expected to favour a queen that is more likely to be their mother and to produce offspring of close kin to them. We used microsatellite markers to study reproductive partitioning between cobreeding Formica fusca queens in a laboratory experiment where workers received a choice between two queens. We expected queens of this species to communicate their reproductive status by chemical communication, because no aggressive interactions between queens have been observed. We found that queens of different reproductive status (with majority, minority or no production) differed in their cuticular hydrocarbon (CHC) profiles. The fecundity of a queen was associated with worker behaviour; the higher a queen's fecundity, the more attention she received from workers. Our results suggest that a queen fecundity signal is encoded in her CHC profile and acts as a pheromone for workers, which respond to the signal by discriminating between queens. (C) 2002 Published by Elsevier Science Ltd.