EFFECT OF GENOTYPE BUT NOT OF AGE OR CASTE ON OLFACTORY LEARNING-PERFORMANCE IN THE HONEY-BEE, APIS-MELLIFERA

The ability to change expression of a behaviour through experience wit h contingencies among important stimuli can enhance the survival and f itness of animals under certain ecological conditions. It would seem p aradoxical if strong variability in learning performance persists even when those conditions are met. In the honey bee, learning about the r elationship between floral odours and the rewards offered by flowers i s important for colony survival. Yet several studies have identified a significant amount of inter-individual variability in olfactory learn ing performance among workers within colonies. This variability could be due to changes in learning performance due to age, to caste-specifi c alteration of motivational state, or to genotypic variability among paternal lines within colonies. Experiments reported herein were desig ned to establish the contribution of all three variables under control led environmental conditions within which significant variability in a measure of learning performance exists. The results indicate that, at least under these conditions and when genotype is not manipulated, ne ither age nor caste had an effect on motivational state or learning pe rformance. Genotype was the only variable that could account for a sub stantial portion of the variability within colonies of honey bees. The refore, manipulation of genotype will be necessary in future studies d esigned to establish the reasons underlying variability in learning pe rformance in natural populations.