Age and Behaviour Related Changes in Responsiveness to Sensory Stimuli; Effects on Learning and Memory in the Honey Bee, Apis mellifera

Abstract

Behavioural tasks performed by honey bee workers change as they age. These changes in behaviour are suggested in the literature to be influenced by genetics, environmental cues, hormones and biogenic amine levels. In this study age- and performance- related differences in behavioural responses to environmental stimuli were identified in honey bee workers. Guard bees were less responsive to air and odour puffs and habituated more rapidly to mild negative stimuli than young bees (1-6 days old) and pollen foragers. However, guard bees showed a higher sensitivity to aversive stimuli, responding with small sting extensions to low voltages (0.1-1 volts). One- and 2-day old bees showed faster habituation to tactile stimuli than older bees. Two day old bees also showed poor acquisition of aversive olfactory associations and showed no retention of aversive olfactory memories. However, 2- and 3-day old bees both showed an ability to learn which odour did not pose a threat and they retained this olfactory memory for at least one hour. Guards and pollen foragers successfully learnt aversive olfactory associations and retained aversive memories for 24 hours. Less than half of the pollen foragers examined showed a conditioned response 24 hours after the last conditioning trial, and even fewer bees retained aversive olfactory memory for 48 hours. Pollen foragers collected during winter demonstrated less robust aversive olfactory learning during the acquisition phase but their memory recall was similar to that of summer pollen foragers. The extinction rate of aversive olfactory memories declined faster in guards than in winter and summer pollen foragers. These results indicate that sensory sensitivity, aversive learning behaviour and memory retention change as a honey bee ages or performs different behavioural tasks.