Pollen stays on bee bodies right where flowers need it for pollination

September 6, 2017
Apis mellifera safe sites with fluorescent sunflower pollen. Credit: Petra Wester

After grooming, bees still have pollen on body parts that match the position of flower pollen-sacs and stigmas, according to a study published September 6, 2017 in the open-access journal PLOS ONE by Petra Wester from Heinrich-Heine-University, Germany, and colleagues.

Flowers depend on for pollination, and flower-visiting collect large quantities of pollen to feed their larvae. However, there has been little work on flower-pollinator interactions in view of this conflict over pollen. Field observations suggest that flower-visiting bees have residual patches of pollen after grooming, and it has been hypothesized that these ungroomed serve as "safe sites" that transfer pollen from one flower to another.

Wester and colleagues tested this hypothesis with two experiments: one assessed bee grooming patterns, and the other assessed whether plants contact these safe sites on bees. In the first experiment, the researchers put individual Bombus terrestris bees and pollen grains in covered jars. As the bees flew, they stirred up the pollen grains and became evenly coated with pollen within minutes. After transferring the bees to clean jars and letting them groom themselves, the researchers counted the pollen grains that remained on safe sites. In the second experiment, the researchers put B. terrestris and Apis mellifera bees in indoor flight cages with where the anthers and stigmas were marked with . By observing the transfer of the dye to the bee, the authors could determine which areas touched the flowers' reproductive organs.

The researchers found that B. terrestris and A. mellifera had similar safe sites after grooming, and that these areas were less groomed by the bees' legs. In both bee species, the waist had the most pollen, followed by the dorsal parts of the thorax and abdomen. Importantly, the fluorescent dye experiment showed that the flowers contacted these same safe sites, allowing for pollen deposition by the anther and for pollen uptake by the stigma. These findings could help focus future studies on, for example, the morphological match between pollinators and flowers, as well as on strategies that both pollinators and flowers use to bypass the conflict over pollen.

For the first time, we experimentally demonstrated the position, area and pollen amount of so-called safe sites at the body of honeybees and bumblebees," says Wester. "We also showed that these specific body areas bees cannot groom are contacted by pollen-sacs and stigmas of several plant species, confirming the importance of the bees' safe sites."

Explore further: Pollination mystery unlocked by bee researchers

More information: Koch L, Lunau K, Wester P (2017) To be on the safe site - Ungroomed spots on the bee's body and their importance for pollination. PLoS ONE 12(9): e0182522. doi.org/10.1371/journal.pone.0182522

Related Stories

Bees use multiple cues in hunt for pollen

November 10, 2016

Bees use a variety of senses and memory of previous experiences when deciding where to forage for pollen, research by the University of Exeter suggests.

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

Crops evolved 10 millennia earlier than thought

October 23, 2017

Ancient hunter-gatherers began to systemically affect the evolution of crops up to thirty thousand years ago – around ten millennia before experts previously thought – according to new research by the University of Warwick.

New discovery challenges long-held evolutionary theory

October 19, 2017

Monash scientists involved in one of the world's longest evolution experiments have debunked an established theory with a study that provides a 'high-resolution' view of the molecular details of adaptation.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

betterexists
not rated yet Sep 06, 2017
So, FIND a material that is sprayed over flowers to magnetically attract those pollen.
This idea is for next millennium, I think.
There are far more things out their to do first.

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.