Pollen is produced by plants to carry the male gametes for reproduction. The fact that these grains are transportable facilitates genetic diversity for the plants. Many plants rely on insects to carry pollen from one flower to another and to initiate the fertilisation process by placing the pollen on the female receptacles (referred to as pollination). Most of these offer the insect an incentive in the form of strategically placed nectar. Both insect and plant have grown to rely on each other for this service.
In addition to collecting nectar, bees also take pollen back to their colonies. Pollen contains lipids (fats), carbohydrates, free amino acids (proteins), minerals, vitamins and other substances. It is virtually the only source of protein for the honeybee and as such it is essential for the growth and development of young bees. Adult bees also use pollen towards the end of the season to develop the fat stores which enable them to survive the winter without foraging. It has been suggested that the quality of different pollens has a direct effect on the longevity of the bees feeding upon it at the developmental stage (Müller).
Bees forage for pollen much closer to the hive in spring (say 100 yards) (Wedmore). Pollen is carried by worker bees on their back legs in the corbiculum - a concave space, fringed with stiff hairs, on the inner side of the tibia or basal joint of the tarsus of a bee.
Pollen grains vary in size from about 5 microns (e.g. forget-me-not) to 140 microns (e.g. hollyhocks). They can be identified by colour, season and (more accurately) by microscopy. Bees tend to mix pollen with nectar or honey and store it in the combs around the periphery of brood cells. In this form it is often referred to as ‘bee bread’.
The study of spores and pollen is referred to as Palynology. The study of pollen grains in honey is called melissopalynology.
Solitary (and bumble) bees also use pollen as a source of protein. Here, the Red Mason bee, Osmia rufa, has laid eggs in beds of pollen for the emerging larvae to eat.
'When used at the right time, pollen substitutes can be a vital supplement for colonies. Start feeding them about 4 to 5 weeks before brood rearing commences, and keep feeding until natural pollen is plentiful:
1 part sodium caseinate (a readily available dairy derivative)
2 parts dried non-active yeast.
Sugar syrup to make a stiff paste (ensure that the sugar syrup is not fermenting, otherwise the patties will blow up).
Combine in a cake mixer or commercial baker's mixer if large quantities are being made. Fill small paper bags with the mix and, when you give them to the bees, open the upper side of the pattie bag.
Note: avoid the use of soya protein in bee feed.'
Health Benefits of Honeybee Pollen
By Piotr Jędrzejuk
Eat Drink Better - March 16, 2011
'For over two years I have been eating 1.2KG of honey on a monthly basis – I’m a huge fan of tea. One day I decided to cut my sugar consumption and replace it with something organic. The first and only substitute that came to my mind was honey. I decided to give it a go, and ever since then I could never switch back to sugar. I was able to taste the artificialness more than ever and was disgusted by it. I was unable to drink the tea and simply poured it down the sink!'
Coloured Scanning Electron Micro-graph (SEM) of an assortment of pollen grains. Pollen grain size, shape and surface texture differ from one plant species to another, as seen here. The outer wall (exine) of the pollen in many plant species is highly sculpted which may assist in wind, water or insect dispersal. This pollen sculpting is also used by botanists to recognise plant species. Pores in the pollen wall help in water regulation and germination. These reproductive male spores produced by seed plants contain the male gametes. Pollen fertilises the female egg, with subsequent formation of plant seeds. (Courtesy of Science Photo Library)
Pollen identification for beekeepers, Sawyer, R (1981) University College, Cardiff Press, or facsimile by Northern Bee Books (2006). A companion illustrated CD of pollen images has been prepared by members of the Harrogate and Ripon Beekeepers' Association. Read more...
Honey identification, Sawyer, R (1988), Cardiff Academic Press.
Anatomy and dissection of the honeybee, Dade, H A (1962 and subsequent reprints), International Bee Research Association
The pollen loads of the honeybee, Hodges, D (1952 and subsequent reprints), International Bee Research Association
Pollen, its collection and preparation for the microscope, White, J (1989), Published by the author
Microscopy: First steps into a secret world, Winsby, R (1996), Manchester Microscopical and Natural History Society
Pollen analysis, Moore, P D, Webb, J A and Collinson, M E (1991), Blackwell Scientific Publications
Pollen Nutrition and Colony Devolopment in Honey Bees
By Irene Keller, Peter Fluri and Anto Imdorf
Pollen is the honey bees' main source of several important nutrients. Consequently, an adequate pollen supply is essential to ensure the long-term survival of a colony and to maintain its productivity. Part 1 of this 2-part review focuses on the botanical composition of bee-collected pollen and its protein and mineral content. Further, we discuss the impact of pollen on honey bee physiology and assess the pollen requirements of individual workers and larvae.
The consumption of high-quality pollen induces the development of the hypopharyngeal glands in young honey bee workers. As protein-rich secretions from these glands are an important component of larval food, a direct relationship between pollen supply and brood rearing can be expected. Consequently, the availability of pollen is likely to be a central parameter influencing the development of honey bee colonies.
What governs protein content of pollen: pollinator preferences, pollen-pistil interactions, or phylogeny?
By T'ai Roulston, James Cane and Stephen Buchmann
Pollen ranges from 2.5% to 61% protein content. Most pollen proteins are likely to be enzymes that function during pollen tube growth and subsequent fertilization, but the vast range of protein quantity may not reflect only pollen–pistil interactions. Because numerous vertebrate and invertebrate floral visitors consume pollen for protein, protein content may influence floral host choice. Additionally, many floral visitors pollinate their host plants. If protein content influences pollinator visitation, then pollinators are hypothesized to select for increased protein content of host plants.