How do honey bees get their buzz? The same way we do Caffeine fix: A honey bee on the flower of a citrus tree. New York: Nothing kicks the brain into gear like a jolt of caffeine. For bees, that is. And they don't need to stand in line for a triple soy latte. A new study shows that the naturally caffeine-laced nectar of some plants enhances the learning process for bees, so they are more likely to return to those flowers. "The plant is using this as a drug to change a pollinator's behaviour for its own benefit," said Geraldine Wright, a honey bee brain specialist at England's Newcastle University . She, with her colleagues, reported the findings in the magazine Science on Thursday. Plants produce all sorts of chemicals that affect animal behaviour: sugar in nectar, memorable fragrances, even substances in fruit that act as laxatives for quick seed dispersal. Lars Chittka, a student of bee behaviour at the University of London said that "to influence the memorability of the signal using a psychoactive drug ... that's a new trick in the book for plants." Dr Wright did not set out to investigate the evolutionary strategies of plants. Her goal was to use the honey bee as a model to study drugs that were commonly abused. Several varieties of coffee and citrus plants have toxic concentrations of caffeine in leaves and other tissues but low concentrations, similar to that in weak coffee, in the nectar itself. The toxic concentrations help plants to fend off predators. Dr Wright conducted learning experiments with bees to see whether they associated a reward with an odour, the reward being either sugar water or a combination of sugar water and caffeine in the same concentrations found in the nectar of coffee and citrus plants. "If you put a low dose of caffeine in the reward when you teach them this task, and the amount is similar to what we drink when we have weak coffee, they just don't forget that the odour is associated with the reward," Dr Wright said. After 24 hours, three times as many bees remembered the connection between odour and reward if the reward contained caffeine. After 72 hours, twice as many remembered. They then tested the effect of caffeine on bee brain neurons and found it could lead to more sensitivity in neurons called Kenyon cells, which are involved in learning and memory. Insect and human brains are vastly different, and although caffeine has many effects on people, such as increasing alertness, whether it improves memory is unclear. But the excitation of the Kenyon cells was similar to the action of caffeine on cells in the hippocampus in a recent experiment on rats, Dr Wright said.