Importance of social stimuli for the development of learning capability in honeybees

The learning ability of the European honeybee, Apis mellifera, is well known. However, in a proboscis-extension reflex (PER) assay, newly emerged and very young worker bees could not associate a given odor (conditioned stimulus, CS) with a sucrose reward (unconditioned stimulus, US): This ability was acquired 5 to 9 days after emergence in workers, while it was accomplished 2 to 5 days after emergence in drones, probably reflecting the earlier onset of flight in drones. When workers are reared individually in a confined condition deprived of colony odor and other social stimuli, they do not develop the ability even after 9 days after emergence. In a series of experiments subjecting the bees to the confined condition for various lengths and timings, the important period for acquiring the learning ability was from day 2 to 6 after emergence. However, even bees that acquired the ability lost it when exposed to the confined (stimuli-deprived) condition for the next 15 days, meaning that the continuous input of appropriate sensory stimuli is essential for both acquiring and maintaining the learning capability.