Music has charms to soothe a savage breast. And, it seems, flowers can calm an aggressive honeybee. Scientists in France and Australia have found that angry honeybees are less likely to attack when exposed to certain floral scents, such as lavender, associated with the promise of food. This occurs even when the bees are provoked into releasing odorous pheromones that recruit other bees into a stinging attack.
The reason appears to be that the bees would rather feast than fight, the researchers said. The bees respond more strongly to the smells related to gathering food than to pheromones calling for war.
Honeybee hives, or colonies, have a queen bee, many drone bees that mate with the queen, and a team of worker bees responsible for foraging, cleaning, and protecting the hive. With having to guard their colony members, workers tend to be the most aggressive, so when threatened these bees emit a scent called a sting-alarm pheromone. This calls other nearby bees into action so they too will prepare to attack the intruder. However, this defense mechanism comes at a cost: Honeybees die after stinging because their stinger is ripped off their body during an attack.
In their study, the researchers triggered aggression in honeybees by rotating a black leather patch inside a glass vessel. They introduced their bees inside this “arena,” as they called the vessel, and roused them additionally with a black feather.
Sooner or later, the bees got peeved and attacked and stung the leather patch. By additionally introducing odorants into the glass vessel, Nouvian and her colleagues could investigate how the bees’ reaction changed in the presence of these substances.
Two chemical compounds decreased aggression in honeybees: 2-phenylethanol and linalool. Both are found in essential oils and emit a pleasant floral odor, with linalool showing an additional touch of spiciness. It is produced by mint herbs. When presented with these odors, the bees were pacified and decreased their attacks against the black patch.
Lavender had the same effect. It is a mixture of linalool and one other odorant. Other floral scents like limonene – the main odor constituent in citruses – didn’t impress the bees at all; they continued attacking with the same frequency.
The researchers surmised that all honeybees have innate preferences for certain fragrances that indicate rewarding nectar-bearing plants.
Were the flower fragrances just stronger than the odor of the alarm pheromone so that the bees couldn’t detect the pheromone? The researchers exclude this possibility. Their experiments, they say, show that “these floral odors act as appetitive signals for bees.”
Honeybees weigh different odorous stimuli and decide which one is the most important, the researchers concluded. And obviously – food is the most important thing on earth. At least, the research seems to show, it is more important than fighting.