Cognitive aging is linked to social role in honey bees (Apis mellifera)

Aging is associated with cognitive impairment in numerous animal species. Across taxa, decline in learning performance is linked to chronological age. The honey bee (Apis mellifera), in contrast, offers an opportunity to study such aspects of aging largely independent of age per se. This is because foraging onset can be decoupled from chronological age, although workers typically first perform tasks inside the nest and later forage outside the hive. Further, early phases of foraging are characterized by growth of specific brain neuropiles, whereas late phases of the forager life-stage are accompanied by accelerated rates of physiological senescence. Yet, it is unclear if these patterns of senescence include cognitive function. The flexibility of worker ontogeny, however, suggests that the bee can become an attractive model for studies of plasticity in cognitive aging that ultimately may lead to insight into mechanisms that govern age-related cognitive decline. To address this potential, we studied effects of honey bee chronological age and of social role on sensory sensitivity and associative olfactory learning performance. Our results show a decline in olfactory acquisition performance that is linked to social role, but not to chronological age. This decline occurs only in foragers with long foraging duration, but at the same time the foragers show less generalization of odors, which is indicative of more precise learning. Foragers that are reversed from foraging to nest tasks, furthermore, do not show deficits in olfactory acquisition. These results point to complex effects of aging on associative learning in honey bees. (c) 2007 Elsevier Inc. All rights reserved.