The queen part in the tolerance between worker bees, Apis mellifera mellifera

The intolerance and the aggressive behaviour of worker bees towards alien individuals of the hive are widely known. But, in particular circumstances, worker bees of different hives can live together without fighting. Thus, it seemed interesting to look for factors which can stop the aggressive behaviour of the honeybee towards alien individuals. Basic to our understanding of these behaviours is the effect of the colony odour. However, colony odour may have various origins, including the hive materials and metabolic products of the workers or the queen. We orientated our research towards investigating the effects of the queen's metabolism. Experiments were made with populations of 75 workers of various ages taken from the same hive and kept in cages. Seventy-two h elapsed between the time when the workers were put in cages and the first observation. Five workers were introduced from cage X into cage Y, and vice versa, and the aggressiveness of the receiver workers towards one worker chosen amongst the five workers introduced was classified from 1 (no aggressiveness) to 5 (struggle and killing of the intruder). Every set of observations lasted 10 min and was repeated daily for 7 days. We demonstrated that the queen's odour played an important part in the colony odour. We now know that : 1) queenless sister workers readily recognize one another, even a long time after their separation (table I); 2) workers living with a queen easily accept their queenless sisters (table II: lines "X en Y"); 3) queenless workers reject their sisters that have lived with a queen for 72 h (table II: lines "Y en X"). The two first results may be explained by aspects of kin recognition but not the last one. We hypothesize that queenless workers slowly lose their queen's odour, while workers with queens are continuously marked by the queen pheromone