Abstract:
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 significantly
higher amounts in laying workers than in non-laying 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 significantly different between the
two species, but in queenless A. cerana colonies the ratio is significant higher than in
A. mellifera, suggesting that in A. cerana, the workers’ pheromonal bouquet is
dominated by the queen compound, 9-ODA. The amount of 9-ODA in laying A.
cerana workers increase by over 585% compared to the non-laying workers, that is
6.75 times higher than in A. mellifera were laying workers only had 86% more
9-ODA compared to non-laying workers.
