Honeybees warn of risky flowers

Matt Walker
Editor, Earth News

Danger lurks behind many petals

Honeybees warn each other to steer clear of dangerous flowers where they might get killed by lurking predators.

Scientists made the discovery by placing dead bees upon flowers and then watching how newly arriving bees react to the danger.

Not only do the bees avoid the flowers, they then communicate the threat when they return to the hive via their well known waggle dance.

The discovery is published in the journal Animal Behaviour.

The honeybee waggle dance is a surprisingly sophisticated mode of communication.

When foraging bees return to the hive, they waggle their bodies in a complex dance first deciphered by biologists more than 40 years ago.

The angle and direction of the forager bees' waggle dance conveys how far and in what direction other more naive bees need to fly to reach flowers that will provide plentiful sources of food.

The crab spider Diaea dorsata is best avoided

Honeybees are also more likely to waggle and dance when returning from food sources containing high concentrations of sucrose.

But now scientists Kevin Abbott and Reuven Dukas of McMaster University in Hamilton, Ontario, Canada have found that honeybees use the waggle dance to do more than just encourage others in their colony to visit bountiful flowers.

Avoiding danger

They trained honeybees to visit two artificial flowers containing the same amount and concentration of food.

They left one flower untouched, making it a "safe" food source for the bees.

On the other flower, they placed the bodies of two dead bees, so they were visible to arriving insects, but would not interfere with their foraging.

A crab spider kills a flower visiting wasp

They then recorded whether and how the bees performed a waggle dance on their return to other members of the hive colony.

On average, bees returning from safe flowers performed 20 to 30 times more waggle runs that bees returning from dangerous flowers.

That shows that the bees recognise that certain flowers carry a higher risk of being killed or eaten by predators, such as crab spiders or other spider species that ambush visiting bees.

What's more, they factor this risk into their waggle dances, tempering them to steer their colony mates away from flowers that might be dangerous.