Queen rearing suppression in the honey bee - evidence for a fecundity signal

Abstract

Previous studies have shown that a pheromone produced in the honey bee (Apis mellifera L.) queen's mandibular glands suppresses the rearing of new queens. The present studies investigated the existence of an as-yet unidentified, brood-associated signal that acts in conjunction with the queen's mandibular pheromone to suppress queen rearing. When we manipulated the levels of synthetic queen mandibular gland pheromone (QMP) and young brood in queenless colonies, there was a 50 % reduction in the number of queen cells reared compared to colonies receiving QMP alone. In a second experiment, colonies containing eggs and young larvae but no QMP reared on average only one queen cell after 24 h, while colonies containing older larvae reared four queen cells, suggesting that combs with younger brood were the source of the second signal. In a third experiment, we attempted to induce queen rearing in the presence of the queen by removing eggs and young larvae in colonies with healthy queens. Six of nine brood-manipulated colonies initiated queen cells, compared with only one of nine colonies receiving a sham manipulation. The results from this experiment suggest that a decline in the brood signal initiated queen supersedure in honey bee colonies. Results from all three experiments clearly demonstrate the existence of a "fecundity" signal that acts with QMP to suppress queen rearing.