This flower smells like a bee under attack

October 6, 2016
A honeybee eaten by a spider with food stealing kleptoparasitic flies. A drop of venom is visible at the tip of the stinger. Credit: Gernot Kunz

A new discovery takes plants' deception of their pollinators to a whole new level. Researchers reporting in the journal Current Biology on October 6 found that the ornamental plant popularly known as Giant Ceropegia fools certain freeloading flies into pollinating it by mimicking the scent of honeybees under attack. The flies find that smell attractive because they typically dine on the drippings of honeybees that are in the clutches of a spider or other predatory insect.

"These flowers have a complex morphology, including trapping structures to catch pollinators, temporarily trap, and finally release them," says Stefan Dötterl of the University of Salzburg in Austria. "We show that trap flowers of this plant mimic alarm substances of western to lure food-stealing freeloader as pollinators. Flies are attracted to the flowers, expecting a meal, but instead of finding an attacked honeybee they are temporarily trapped in the non-rewarding flowers and misused as pollinators."

About four to six percent of plants, including the fly-pollinated genus Ceropegia, are pollinated by deceit. They engage in false advertising by appearing to offer a reward, such as pollen or nectar, a mating partner, or an egg-laying site. The new study is among the first to describe a plant that achieves pollination by mimicking the scent of an adult carnivorous animal's dinner.

Study co-authors Annemarie Heiduk and Ulrich Meve from the University of Bayreuth in Germany got curious when they realized that the flies pollinating Ceropegia sandersonii were Desmometopa. The flies are known as kleptoparasites, commonly feeding on honeybees eaten by spiders.

"We asked ourselves how the flies might find such honeybees," Dötterl says.

When observing a honeybee caught by a spider, they noticed that the bee extrudes its sting and releases a drop of venom. The bees' venom is known to contain volatile alarm pheromones, which serve to call and attract nest mates for help. They wondered whether the plant might be taking advantage of this line of communication among honeybees.

Preliminary experiments showed that honeybees under simulated attack are highly attractive to the flies. In the new study, the researchers show that the floral scent of C. sandersonii is indeed comparable to volatiles released from honeybees when under simulated attack. Some of those shared compounds also elicit a response in the antennae of pollinating Desmometopa flies and are strong attractants for these insects. The evidence is clear: an unusual blend of compounds emitted by C. sandersonii lures kleptoparasitic flies into the plants' trap flowers.

The researchers say they now hope to find out whether other plants, including other species of Ceropegia pollinated by kleptoparasitic flies, use a similar reproductive strategy.

Explore further: How trap-flowers attract and deceive pollinating food thieves

More information: Current Biology, Heiduk et al.: "Ceropegia sandersonii Mimics Attacked Honeybees to Attract Kleptoparasitic Flies for Pollination" http://www.cell.com/current-biology/fulltext/S0960-9822(16)30879-X , DOI: 10.1016/j.cub.2016.07.085

Related Stories

How trap-flowers attract and deceive pollinating food thieves

December 15, 2014

Researchers have discovered a new pollination system that involves food-thieving flies as pollinators. These flies feed on insect secretions, available when a spider, a praying mantis, or other predatory arthropods feed on ...

Flies are the key pollinators of the High Arctic

September 28, 2016

Forget the view of the Arctic as an icy desert devoid of life. The Arctic summer is buzzing with insects – and here as everywhere else, plants rely on them for pollination. But who are the insects driving the pollination ...

Orchid wears the scent of death

March 14, 2011

Sex and violence, or at least death, are the key to reproduction for the orchid Satyrium pumilum. Research led by Timotheüs van der Niet at the University of KwaZulu-Natal shows that the orchid lures flies into its flowers ...

Threat posed by 'pollen thief' bees uncovered

October 9, 2015

A new University of Stirling study has uncovered the secrets of 'pollen thief' bees - which take pollen from flowers but fail to act as effective pollinators - and the threat they pose to certain plant species.

Recommended for you

Molecular microscopy illuminates molecular motor motion

July 25, 2017

A toddler running sometimes loses footing because both feet come off the ground at the same time. Kinesin motors that move materials around in cells have the same problem, which limits how fast they can traverse a microtubule ...

Discovery of why emus are grounded takes flight

July 25, 2017

Researchers from Monash University's Biomedicine Discovery Institute have helped solve the mystery of how emus became flightless, identifying a gene involved in the development and evolution of bird wings.

Breaking boundaries in our DNA

July 25, 2017

Our bodies are composed of trillions of cells, each with its own job. Cells in our stomach help digest our food, while cells in our eyes detect light, and our immune cells kill off bugs. To be able to perform these specific ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.