The effects of queenlessness on the maturation of the honey bee olfactory system

Abstract

During the first week of adult life the olfactory system of the honey bee undergoes a critical period of maturation [Masson and Arnold, Organisation and plasticity of the olfactory system of the honeybee, Apis mellifera, in: Menzel and Mercer (Eds.), Neurobiology and Behaviour of Honeybees. Springer-Verlag, Berlin, 1987, pp. 280–295]. This is accompanied by dramatic increases in the volume of the antennal lobes [Winnington et al., Structural plasticity of identified glomeruli in the antennal lobes of the adult worker honey bee. J. Comp. Neurol., 365 (1996) 479–490], centres of the brain that receive direct input from primary olfactory receptor neurons housed in the antennae of the bee. Here, we show that during the first 4–6 days of adult life there is a significant increase in the percentage of bees that respond to a conditioned olfactory stimulus after a single conditioning trial and, furthermore, that the ontogeny of this olfactory learning behaviour is altered significantly if the queen is removed from the colony. The absence of a queen during early adult life also has site-specific effects on the maturation of the antennal lobes of the brain. These results show for the first time that the queen's presence in a colony has a significant impact not only on the behaviour of the adult worker honey bee, but also on the structure of the brain.