Cocaine repels most insects -- which is why the coca plant makes the chemical in the first place. But in a surprising new finding, U.S. and Australian researchers reported Friday that honeybees are susceptible to the drug's insidious lure.
They become addicted, and even suffer withdrawal symptoms when they no longer have access.
The findings, reported in the Journal of Experimental Biology, may help explain the "waggle dance" used by foraging bees to tell their hive-mates where to find food, and even provide hints about how the drug works in the human brain.
Researchers led by entomologist Andrew Barron of Macquarie University in Sydney trained a hive of bees to forage at a nearby supply of sugar water. Then they applied minute quantities of cocaine to the backs of foragers.
He and neuroscientist Gene Robinson of the University of Illinois found that the bees' dance remained tightly controlled, providing accurate directions to the food source. But the insects now demonstrated an unusually strong response to food, acting as though a weak solution of sugar water was a much better food source and communicating their findings much more enthusiastically to hive-mates.
The bees grew tolerant of the drug, meaning continually higher doses were required to achieve the same effect. But if they were given it for a week and then refused access, they were severely affected, becoming much less able to learn new tasks, such as distinguishing between two scents, the team found.
Robinson had previously shown that a chemical called octopamine in the brains of bees influences their altruistic waggle dancing. The new findings suggest that cocaine interacts with this chemical system, accentuating its effects.