The use of electromyogram recordings to quantify odourant discrimination in the honey bee, Apis mellifera

Proboscis extension conditioning of worker honey bees (Apis mellifera carnica) was employed to compare responses to several different conditioned odourants as well as to compare generalization responses to odourants to which they had not been exposed during conditioning (i.e. novel odourants). Quantification of the bees' responses was through analysis of the muscle potential evoked in the M-17 muscle, which operates during proboscis extension, retraction, and rhythmic movements of the glossa throughout the response (J. Insect Physiol. 33, 501-507, 1987a). Electromyogram quantification allows for more accurate description of the graded nature of the response and demonstrates the usefulness of electromyogram recordings in the quantification of behaviour. Results show that, after an equivalent amount of conditioning, bees respond more strongly to some conditioned odourants than to others. Although responses occur to novel odourants, they depend on the combination of conditioned odourant and the novel odourant presented. Furthermore, generalization to novel odourants within the same chemical class as the conditioned odourants is usually, but not always, stronger than generalization to odourants of different classes.