Angry Bees Are Easily Distracted By Food, Study Finds

The Washington Post    By Rachael Feltman   December 23, 2015

You know those Snickers commercials about how easy it is to get angry when you're in need of a snack? 

Well, scientists haven't exactly shown that honey bees get "hangry," but the word certainly comes to mind when reading a new study on bee aggression. In the study, published Tuesday in Nature Communications, researchers led by Martin Giurfa at the University of Toulouse and Judith Reinhard of the University of Queensland found that honey bees put on the war path were quite easily put off it by the scent of food.

When a guard bee senses a predator using visual cues like color and movement, it sends out pheromones -- chemicals that illicit an unconscious, automatic physical response in other members of the same species -- to put soldier bees inside the nest on high alert. This puts the bees into kamikaze mode, since any stinging attack leaves the species Apis mellifera sans several internal organs. At least 40 chemical compounds have been found in the pheromone cocktail that calls honey bees to war, but the main component, isoamyl acetate, is enough on its own to make a soldier bee ready to die for the cause.

Previous research has shown that bees and other insects can sometimes get confused by exposure to more than one kind of pheromone. But researchers wanted to see whether the scent chemicals produced by flowers might have any effect.

First, they had to make some honey bees angry, which they did by placing them in an "arena" with an annoying moving target:

Two bees are placed into a container with a moving target and are unaffected by the movement until one of the bees strikes. (Morgan Nouvian (CRCA – QBI)

Two bees are placed into a container with a moving target and an alarm pheromone. The reaction to the sting alarm pheromone can be extremely fast, as evidenced by this pair of bees attacking the moving dummy within seconds of their introduction inside the test arena. (Morgan Nouvian (CRCA – QBI))

But when flowery scents like lavender were added, the bees chilled out. It wasn't simply a question of masking one scent with another -- some food-related scents, like citrus, had no effect -- but the compounds linalool and 2-phenylethanol, along with the scent of lavender (a mix of linalool and other chemicals) seemed to block the aggressive response to the alarm hormone.

Since stinging is such a nasty business, it's not surprising that bees might be hardwired to avoid it in favor of accessing available food for the hive. But the bees didn't have to rely on memories of previously foraged snacks in order to decide what food trumped fighting. Even newly emerged bees, who had never foraged and therefore had no experiential preference for particular flowery smells, were calmed by the lavender-related scents.

The researchers told Live Science that any calming effect of lavender on bees is probably unrelated to the anecdotal calming effect it has on humans. Lavender might be a pleasant, calming scent for a human bubble bath, but for a bee it's like the scent of a juicy burger (if that burger sent out chemical signals that literally drew your body toward it).

But that doesn't mean that humans can't benefit from the study.

"We certainly see great potential for applications to beekeeping," first author Morgane Nouvian, a graduate student at both the University of Queensland and the University of Toulouse, told Live Science. "Developing a product based on our results — for example a scented hand spray [or] cream, or an odor-releasing device to place at the hive entrance — could certainly help reduce the number of bees stinging while [beekeepers are] handling the hives. This method would be a great alternative to the current use of smoke and repellents, because we would be tricking the bees with something that they actually 'like,' and it would thus likely be less stressful for them."

Since constant exposure to venom actually makes beekeepers more likely to become allergic to it than the general population, a product like that would be pretty sweet.

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