Brushes Clean Off Pollen

yellow and black bee covered in yellow pollen in close up photo

Biological Strategy

Bees

Holly Kerstiens

Image: Dejen Mengis / Flickr / Public Domain - No restrictions

Distribute Solids

Solids include resources such as food, seeds, spores, and leaves, which living systems must sometimes move to accomplish various activities such as pollinating, feeding their young, or building shelters. To effectively distribute solids, living systems must use strategies appropriate to the sizes and types of solids and the media in which they exist (air, water, or another medium). This may entail strategies beyond simply holding and carrying solids. For example, some seeds are carried by the wind to new locations for germination. Others–like the burdock plant’s hooked seeds–cling to animal fur to be transported.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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The basitarsal brushes of bees are used to clean the pollen off their faces while they forage.

The basitarsal brush is a collection of hair on the last segment of the foreleg. This brush is used during pollination. As bees forage, they can rub the anthers of the flower on their faces and collect pollen all along their heads. The bees then use the brush on their leg to remove the pollen and place it on structures designed for pollen transport. The brush may also be modified to collect oil from flowers, with the ability to do so arising independently in multiple groups.

A brush is defined as a group of hairs with little organization, in comparison to a pollen comb where the hairs make up a single row.

Similar brushes may be found on the tarsus and femur of the hind and mid legs. Variation is seen in the size, density and shape of the hairs that make up the brush, based on the type of pollen collected and any specializations for other substances like oil or nectar.

This information is also available from the University of Calgary Invertebrate collection, where it was curated as part of a study on design inspired by bees.

Image: Rob Alexander / CC BY NC - Creative Commons Attribution + Noncommercial

The foreleg of an Osmia bucephala with the basitarsal brush highlighted.

Image: Sierra Williams / Public Domain - No restrictions

The foreleg of an Osmia distincta with the basitarsal brush highlighted.

Image: Sue Boo / Public Domain - No restrictions

The foreleg of an Osmia lignaria with the basitarsal brush highlighted.

Image: Aaman Mengis / Public Domain - No restrictions

The foreleg of an Osmia texana with the basitarsal brush highlighted.

Last Updated April 3, 2019

References

“Oil-collecting bees have a striking array of pads, brushes, or combs of flattened setae (Figs. 6-3, 110-3a) with which to absorb or scoop the oil and to transport it back to the nest, sometimes mixed with pollen. The morphological details are discussed and illustrated by Vogel (1966 to 1990), Neff and Simpson (1981), and Cocucci, Sérsic, and Roig-Alsina (2000).” Michener 2007:18

“Pollen is commonly removed from anthers by the front tarsi or is dusted onto the body of the bee by its movement among floral parts. The forelegs may be pulled through the mouthparts if the bee eats the pollen, or they are pulled through the flexed middle legs whose opposable midfemoral and midtibial brushes remove the pollen.” Michener 2007:18

Book

The Bees of the World: Second Edition

John Hopkins University Press | Michener CD.

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