The pheromones of laying workers in two honeybee sister species: Apis cerana and Apis mellifera

When a honeybee colony loses its queen, workers activate their ovaries and begin to lay eggs. This is accompanied by a shift in their pheromonal bouquet, which becomes more queen like. Workers of the Asian hive bee Apis cerana show unusually high levels of ovary activation and this can be interpreted as evidence for a recent evolutionary arms race between queens and workers over worker reproduction in this species. To further explore this, we compared the rate of pheromonal bouquet change between two honeybee sister species of Apis cerana and Apis mellifera under queenright and queenless conditions. We show that in both species, the pheromonal components HOB, 9-ODA, HVA, 9-HDA, 10-HDAA and 10-HDA have signiWcantly higher amounts in laying workers than in nonlaying workers. In the queenright colonies of A. mellifera and A. cerana, the ratios (9-ODA)/(9-ODA + 9-HDA + 10-HDAA + 10-HDA) are not signiWcantly diVerent between the two species, but in queenless A. cerana colonies the ratio is signiWcant higher than in A. mellifera, suggesting that in A. cerana, the workers’ pheromonal bouquet is dominated by the queen compound, 9-ODA. The amount