Using a Y-maze to Assess the Aversive Learning Ability of Worker and Queen Honey Bees (Apis mellifera).

Abstract

Aversive learning is the ability of an organism to learn to associate a negative (aversive) experience with a predictive cue. This fundamental skill has been observed to some degree in a vast array of animals from invertebrates to mammals. In particular, honey bees have been used to study learning since the 1900’s when Karl von Frisch started to ask questions about their memory, learning ability and colour vision. This revealed some of the complexities of honey bee life including how they perceive the world around them. Due to their social structure, easy accessibility and upkeep, and a long history of domestication and study, honey bees are a particularly useful organism to examine learning. This has lead to reliable and repeatable methods to be developed as well as techniques to investigate the underlying neurological, chemical and behavioural mechanisms involved. However, honey bees are not all equally skilled at learning due to a number of physiological and behavioural differences between bees that perform various tasks within the colony. Aversive learning, in particular, may prove to be a very complex system that is affected by the environment within the hive (e.g. by pheromone) and potentially other external factors (e.g. foraging history). For example, exposure to queen mandibular pheromone (QMP) has been shown to reduce the learning ability of young worker bees. The effects of QMP on the queen herself and her general ability to learn have received little attention. To date, most research into honey bee learning focuses on appetitive learning which involves training the bee to associate a neutral cue with a reward (food). The potential for aversive learning protocols has just begun to be realised. Until recently, aversive learning in honey bees has relied on a sting extension response to indicate learning. However, a more relevant method that more readily aligns with other species that have been studied is to examine the approach/avoidance behaviour of honey bee towards a conditioned cue in a Y-maze. Following from this, my Masters research centres around the use of the Y-maze to investigate the aversive learning ability of different groups of honey bees using odorants as the conditioned cue and an electric shock as the aversive stimulus. This study shows that honey bees have innate preferences for some odours over others, and that this preference can be maintained over a 24 hour time interval. Behavioural responses to odours can be altered through conditioning and be observed in a Y-maze as time spent with the odour; however, there is no difference in the change in behaviour between different groups of honey bee (nurses, pollen foragers, mated queens, and virgin queens). This Master’s thesis further explores the potential of the Y-maze as a tool to study aversive learning in honey bees and speculates on its use in a range of different scenarios.