Correlates of ester metabolism with age-related polyethism in Apis mellifera

Aliphatic esters are widespread secondary metabolites in plant tissues, including pollen, a principal food source for the western honey bee, Apis mellifera. Present study shows that midguts from different worker stages--one-day-old adult worker, nurse bee and pollen forager--and from drones are all capable of esterase-mediated detoxification of the aliphatic esters octyl butyrate, octyl acetate, hexyl butyrate and butyl butyrate. Esterases break down these four aliphatic esters to the corresponding alcohol and acid. It also shows that nurse bees and one-day-old young adult bees have higher metabolic rates than pollen foragers and drones. Because nurse bees are responsible for feeding larvae and the queen, their elevated rates of ester metabolism may be related to their need to process pollen and honey efficiently to fuel their production of larva food and royal jelly. One-day-old adult workers perform cell-cleaning behavior and their higher ester metabolism rate may allow them to deal with waste processing. In contrast to young workers, pollen foragers and drones do not eat raw pollen directly, which may be an explanation of their lower ester metabolism rate.