Memory Traces in Honeybees

Abstract

Bees learn quickly and effectively the signals which mark a nectar source. The memory for these signals (colors, odors) is characterized by behavioral experiments. Four sequential memory stages - called working memory, early, late and permanent memory - are found, which differ with respect to their sensitivities to unrewarded choices, to new learning trials, and to amnestic treatments. The neuropiles in the brain are differentially involved in the respective memory traces for odor signals. It is concluded that the primary afferent structure, the antennal lobe, participate only in the working memory phase. The most important neuropiles for memory formation are the mushroom bodies. The content of the early and late memory differs for a floral odor, but not for an attractive pheromone component. Genetic selection for low learning performance reveals bees, which lack the late memory but are unaffected in the early memory. The results are discussed in relation to the adaptations of the memory stages to the particular search behaviour of bees at floral patches.