In an exciting revelation that has potential implications for the apicultural industry, as well as for brain research, University of Otago researchers have succeeded in unravelling one of the mysteries that surround the honey bee queen's ability to control the behaviour of her workers.
Department of Zoology staff at the University of Otago two years ago discovered that queen bees manipulate their offspring's behaviour by releasing a pheromone that blocks aversive learning in young bees.
Professor Alison Mercer and Dr Kyle Beggs, in a paper published in the international journal Current Biology, have now identified the molecular target of this pheromone. Queen pheromone - or more specifically a significant component of it, called homovanillyl alcohol or HVA - activates just one of three honey bee dopamine receptors, altering dopamine signalling in the brain and, consequently, the behaviour of young bees.
One of HVA's effects is to curb young bees' aversive learning ability (their ability to store the memory of unpleasant experiences in the brain and, consequently, to predict punishment). Why does the queen do this? Her pheromones have unpleasant effects; they impair motor activity and block worker ovary development. Preventing young bees from developing aversive memories against the queen's odours ensures young bees continue to tend the queen - thus safeguarding the future of the queen and, ultimately, the colony.
"Evolution has provided queen bees with a chemical that selectively blocks aversive learning but leaves reward learning intact," says Professor Mercer. "Two years ago we identified which chemical was responsible for these effects, and now we have discovered how the chemical works."
Establishing a link between changes at the behavioural level and events at a cellular and molecular level is generally very difficult because the processes underlying events such as learning and memory are complex.
"This is an important breakthrough because it will help us understand more clearly how memories are formed, and how brains tell the difference between memories that predict punishment and memories that predict reward."
"There is a great deal of evidence now that mechanisms underlying learning and memory are common to many species, and that important brain chemicals such as dopamine operate in very similar ways in vertebrate and invertebrate animals."
Professor Mercer and Dr Beggs are now starting to explore the effects of queen pheromone on vertebrate dopamine receptors. They are also establishing links with other researchers working on vertebrate systems to try to determine whether queen pheromone/HVA has potential for use in neurological research, as the importance of dopamine in brain function is widely recognized, if not fully understood.
Furthermore, with synthetic queen pheromones already in use as a tool for controlling queenless hives, Mercer believes their research findings could be applied in apiculture. Equally the insight they have provided into queen bee survival mechanisms could prove useful to efforts aimed at halting the current dramatic worldwide decline in honey bee populations, especially in countries like New Zealand which rely heavily on honey bees for crop pollination.
Editor's Note: Original news release can be found here.