1Laboratoire de Neurobiologie Comparée des Invertébrés, INRA, B.P. 23, 91440 Bures-sur-Yvette, France.
2Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, CC 276 - (7620) Balcarce, Argentina.
3Department of Biological and Ecological Chemistry, IACR-Rothamsted, Harpenden, Hertfordshire AL5 2JQ, UK.
Complex odor recognition in the honey bee was investigated using two behavioral assays: (1) the classical conditioning of the proboscis extension on restrained individuals, and (2) the observation of foragers visiting an artificial feeder in a flight room. Nine floral compounds, previously identified as oilseed rape flower volatiles, were tested either individually or in mixtures. First, the acquisition rate of the nine individual compounds was determined in the conditioned proboscis extension assay. Second, the discrimination of the individual compounds after conditioning to a mixture, was studied using the two behavioral assays in parallel. After conditioning to a complex mixture, honey bees established a hierarchy among the components, with some of them accounting for a major part of the behavioral activity of the mixture. Both behavioral assays led to the same classification of compounds, indicating a good agreement between discriminating abilities of restrained individuals and of a population of foragers. The key compounds for recognition of these mixtures were those which were well learnt when presented individually. However the recognition of some compounds was affected by interactions with the other components of the mixture, the activity of some compounds being either enhanced or reduced.