Pollen provides essential nutrients for a honey bee colony. To ensure these nutrients are available, honey bees will collect roughly 57 kg of pollen per year (average for ~20,000 bees in one colony). During the collection and storing process, pollen is mixed with nectar and bee salivary secretions to create bee bread. Once transformed into this sweet substance, nutrients within the pollen grain can be enjoyed by a honey bee {5}.
Pollen Composition
Approximately 250 substances can be found in pollen {1}. Of these substances, bees benefit from proteins, lipids, vitamins, and minerals {3; 5}. Variations of the pollen components range greatly depending on the botanical and geographical origin. Differences of chemical composition can even be seen within the same plant species since the development of the pollen is dependent on the health of the plant, region, season, and year. For example, pollen cultivated by bees in the spring tend to have higher protein content than in consecutive seasons {1}. Because of this fluctuation of nutrients available in each plant, bees depend on a diverse plant source.
Honey Bee Pollen Consumption
The health of a colony largely depends on whether the bees and larvae are receiving adequate nutrition. Although honey bees can survive a long time on carbohydrates found in honey, pollen consumption increases a bees longevity {2}. Worker bees digest the majority of the pollen which they then feed queens, drones and larvae via food jellies {4}. On average, worker bees will consume 2.4 to 4.3 mg of pollen per day. This allows the bees to develop
essential traits such as mature flight muscles and hypopharyngeal glands essential for communication in the colony {2}. Yet it is the larvae that depend on bee bread the most to develop. During the brood rearing process, a single larva can consume 124 to 145 mg of pollen {5}. If a larva is not provided with a sufficient amount of nutrients from pollen, the colony may abort the brood rearing
process {2}.
Polygonaceae (left) Prunus (middle) and Pulsatilla patens (right) have all been brought in by the CU Denver Bee Project's honey bees. To view more types of pollen our bees are collecting visit our Pollen Atlas.
Influences on Pollen Nutrition and Availability
It is imperative that bees have access to a variety of pollen so that the hive thrives. Unfortunately, anthropogenic impacts have increased the stress on bees to find adequate pollen variety. Monoculture has drastically altered food availability for bees, often leading to an insufficient nutrient diet. This agricultural method lacks pollen diversity and often contaminates what pollen is available by using pesticides {2}.
Additionally, humans' alteration of the landscape has affected the balance of wind-pollinated (anemophilous) plants to insect-pollinated (entomophilous) plants. Wind-pollinated plants, such as corn, produce abundant pollen yet have low nutritional value. Whereas insect-pollinated plants provide high concentrations of nutrients for honey bees {6}. Although wind-pollinated plants aren’t nearly as nutritious, they are much of what we plant in urban areas. Results from the CU Denver Bee Project are indicating that bees in Denver’s urban and agricultural regions utilize more wind-pollinated plants. However, in more suburban locations honey bees are resourcing more pollen from more variety of insect-pollinated plants.
Resources for a Happy Healthy Bee
One of the best ways to ensure that a happy healthy bee is receiving enough pollen is by providing a pollinator friendly environment. The Pollinator Partnership and NAPPC have created a plant guide specific for supporting pollinators within the Colorado plateau semidesert region. Colorado Native Plant Society has also provided tips on a creating a bee friendly environment in the Low Water Native Plants for Pollinators article. To learn more about our research on bee health in the urban and suburban environments visit our
website at CU Denver Bee Project.
References
1. Alvarez-Suarez, J. M., & SpringerLink (Online service). (2017). Bee products - chemical and biological properties (1st 2017 ed.). Cham: Springer International Publishing. doi:10.1007/978-3-319-59689-1.
2. Brodschneider, R., & Crailsheim, K. (2010). Nutrition and health in honey bees. Apidologie, 41(3), 278-294. doi:10.1051/apido/2010012
3. Di Pasquale, G., Salignon, M., Le Conte, Y., Belzunces, L. P., Decourtye, A., Kretzschmar, A., . . . Alaux, C. (2013). Influence of pollen nutrition on honey bee health: Do pollen quality and diversity matter? PloS One, 8(8), e72016. doi:10.1371/journal.pone.0072016
4. Keller, I., Fluri, P., & Imdorf, A. (2015). Pollen nutrition and colony development in honey bees: Part 1. Bee World, 86(1), 3-10. doi:10.1080/0005772x.2005.11099641
5. Ellis. A., Ellis J., O'Malley M., Zettle Nalen C., (2013). The Benefits of Pollen to Honey Bees. University of Florida IFAS Extension
6. Mader, E., Spivak, M., Evans, E., 2010. Managing Alternative Pollinators: A Handbook for Beekeepers, Growers, and Conservationists. SARE. https://www.sare.org/resources/managing-alternative-pollinators/
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