Issue Date: July 23, 2007
USING CHEMICALS to prevent someone from forging bad memories smacks of brainwashing, but this is precisely what a queen bee does to the young worker bees that tend to her (Science, DOI: 10.1126/science.1142448).
Queen bees keep their young servants happy by means of homovanillyl alcohol (HVA). It is one of several pheromones a queen uses to maintain control of her hive.
"We've known for a while that the queen's pheromones block ovary development in worker bees and inspire the worker bees to clean and feed her," says Alison Mercer, a zoologist at the University of Otago in New Zealand. "But the big discovery is that HVA is directly influencing brain chemistry."
Mercer and her colleagues Vanina Vergoz and Haley Schreurs found that when young bees were exposed to HVA, they were incapable of learning to associate a nasty experience with a smell, a process that neurobiologists call aversive learning. HVA did not prevent the association of a good experience with a smell, so-called appetitive learning.
"We weren't expecting that the queen could maintain control of worker bees in such a profound and selective way," says Mercer.
The social perk achieved by preventing these young nurse bees from developing aversive memories against odors in the hive-including the queen's own odor-is colony security, notes neurobiologist Giovanni Galizia of the University of Konstanz, in Germany, in a commentary accompanying the Science report. Thwarting bad memories reduces aggressive behavior among the masses deep within a hive.
HVA bears striking chemical similarity to dopamine, the neurotransmitter that mediates aversive learning in bees. Mercer is currently evaluating whether HVA physically competes with dopamine for receptor binding, thereby blocking dopamine-induced aversive learning.
Mercer is also trying to tease out how HVA's negative memory blocking weakens with bee age. Older bees don't tend to the queen but instead brave friend and foe in search of nectar, a role where aversive learning has long-term benefits to both the queen and the hive.
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