BackBeekeeping Made easy Pollen and Honey
Topics included in this lesson:
Any student of beekeeping needs to know some basic facts about pollen and honey. You should realize that honey, pollen, wax, royal jelly, bee venom, propolis, queens and bees are all at times products of the hive. Services rendered by a hive includes pollination.
A
honey bee must forage for food to supply food for its own metabolism, to
feed young
growing larva, and to provide a surplus of honey and pollen for winter and spring
survival. Eva Crane in her fine book, A Book Of Honey
estimates that it takes three orbits around the earth to produce one pound of
honey and during each orbit one ounce of honey is used as fuel.
A colony of bees needs a large work force to gather the necessary nectar and pollen if it is to survive. The beekeepers share of honey produced by a colony of honey bees depends on the beekeeper managing the bees so that large populations of bees are maintained to gather enough for the bees to survive on over winter and get the extra that the beekeeper will harvest.
I am indebted to a number of sources for the material about pollen used in this discussion. By far the most important source I used was: Agriculture Handbook No. 496 "Insect Pollination of Cultivated Crop Plants. This was published in 1976 by U.S.D.A. Some of the other books used were: Honey Plants of Iowa , 1930, Pollen Grains by R.P. Wodehouse published 1935, The Pollen Loads of the Honey Bee by Dorothy Hodges published 1984, Pollen grains of Canadian honey plants by Crompton and Wojtas published in 1993 and Insects and Flowers by F. G. Barth published in 1985.
Adequate pollen stores are required by a hive of bees any time brood is being raised. It has been estimated that a hive might use 40 to 70 pounds of pollen a year and those who collect pollen in something called pollen traps can attest to the fact that bees bring in large amounts of pollen. Many bee classes and books recommend the use of pollen substitute in the spring when brood is being raised. When to use a pollen substitute will be discussed in a later section.
Pollen supplies young nurse bees with the ability to produce "royal jelly" sometimes called bee bread which is fed to the young larva.
Royal jelly This substance is rich in the protein, vitamins, fats and minerals which are converted by the worker bees pharyngeal glands discussed in an earlier chapter into a creamy substance which is fed to young larva. Royal jelly is also produced commercially as a product of the bee hive. For those interested in producing royal jelly we suggest you check out queen rearing. Bees feed young queen larva with mass amounts of royal jelly. This can be collected (harvested) from queen cells cups and sold. Most of the commercial production of royal jelly is located in China due to the very low labor cost. Producing and collecting Royal jelly is very labor intensive.
Pollen is produced by plants. Some plants depend on insects to transport pollen from one plant to another for fertilization to take place. The male gametophyte is enclosed within a pollen grain and when it germinates a pollen tube will make its way to the ovary of the plant where the male gametes reaches an egg cell and a seed will result.
This is a picture of a perfect flower (Apple) taken from Insect Pollination of Cultivated Crop Plants (Agriculture Handbook No. 496).
We should have a basic working knowledge of a flowering plant. In this case, I have chosen an apple blossom to show the various parts. There are four unique features of this apple blossom that are high lighted.
For an apple tree to produce apples, pollination must take place. The fruit is adjoining tissue that develops around the seeds in the ovary. If the flower is fully pollinated the seed set will produce an apple fully developed. If the flower is only partly pollinated (some seeds fail to set) then the apple will be distorted -- lopsided. For pollination (fertilization) to take place, pollen grains must be transferred from the anther to the stigma. Honey bees visit apple flowers for the ample supply of nectar and pollen. In reaching for the nectariferous areas at the base of the flower they come into contact with pollen grains which adhere to the many hairs on the bees body. As the bee flies from blossom to blossom it transfers these very small pollen grains on the stigma of the blossoms it visits thus pollinating the plant. The reward for the bees is the nectar gathered and the pollen brushed from its hairs by the special comb on its legs and carried back to the hive in its pollen basket.
Pollen
grains are very small. They vary in color and shape. Pollen
can be detected in honey and is used as a way of identifying nectar
sources. Since honey is produced from a number of nectar sources, it will
also have a number of pollen indicators as well. Generally speaking,
if a honey sample contains 45% pollen grains from an individual plant source it
is considered predominant. Secondary dominating rating is 16 to 45%
of a plant source in a honey sample. Vary rarely will a honey
sample be 100% of one source.
For example, if in early spring one would sample some honey from a hive, one would find pollen in the honey from maple, apple, willow, dandelion, and others. Thus the nectar making up that honey came from maple, apple, willow, dandelion and other sources.
What is in bee pollen?
A number of Chemical analysis of the composition of bee pollen have been done. These studies have found: amino acids, minerals such as potassium, magnesium, calcium, copper, iron, silicon, phosphorus, sulfur, chlorine, and manganese, vitamins and hormones, water, reducing sugars, starches, fatty acids and others. It has been referred to as the "perfect food" by some.
What is sweeter than honey?
What is more pure or more nourishing?
It is the milk of the aged, it prolongs
their existence, and when
they descend into the tomb, it still
serves to embalm them.
Alexis Soyer The Pantropheon 1853
Humans have been gathering honey from the honey bee for at least the last 10,000 years. We can document this through cave drawings found in caves in Spain, Natal, South Africa, and India. For a rather complete story of man's story and beekeeping, I would suggest a copy of Eva Crane's book, The Archaeology of Beekeeping. Our interest here is to describe honey as a product of the hive.
From the very beginning of my beekeeping education, I can remember Vic Thompson, the right hand man of Walter Rothenbuler of Ohio State University fame, correcting my use of various beekeeping terms.
Honey is not nectar. It is created from nectar by the honey bee. So bees do not gather honey from plants but rather they gather nectar from plants which is then converted by them into honey! Lets take a look at this process.
Nectar undergoes a physical and a chemical change to become honey.
The Physical change occurs as the bees reduce the amount of moisture in nectar. Nectar may have as much as 70 to 80% moisture. Dr. James Tew of Ohio State University has often describe the honey bees behavior of collection flights as, "shopping for nectar with the highest sugar content much as a housewife shops for bargains at the local grocery store." Most flowers secrete nectar but this nectar is not always attractive to honey bees. Thus, honey bees will visit flowers which provide the honey bee with just the right access to its nectar rewards. After gathering the nectar, the bee must reduce the moisture in the nectar to less than 18.6%. This 18.6% figure is the maximum amount of moisture in honey which prevents fermentation at or below this moisture level.
The chemical change occurs as the bee change sucrose (the sugar content of nectar) into the sugar of honey (glucose and fructose). We will take a look at both processes in more detail.
As we discussed above in the pollen section, a honey bee visits a flower to gather nectar and in the process transports pollen. The nectar is located in nectaries that secrete a liquid containing sucrose. Honey bees (Apis mellifera) have rather short proboscises compared to other insects. The proboscis is a sucking tube. In the honey bee the proboscis is about 6.5 mm compared to the bumblebee with a proboscis that varies from 8 to 16 mm according to species. In the Lepidoptera family (moths and butterflies) the proboscis varies from 16 mm to 250 mm. As a result, certain flowers are not desirable to honey bees although they produce good amounts of nectar. Honey plants are covered in Level II course work.
You should take some time to examine a honey bee gathering nectar and pollen. They will crawl over the corolla of flowers probing with their proboscis into the nectaries. They will hurry from flower to flower searching for an inviting liquid reward. The nectar is sucked from the plant and the honey bee will dilute it with saliva containing secretions from several glands such as the hypopharyngeal gland which add enzymes: invertase, diastase, and glucose oxidase. The nectar load is then stored in the honey crop (stomach) for the trip back to the hive.
Honey is made in the hive!
Upon arriving at the hive, the foraging bee seeks out a house bee to transfer her nectar load and once the nectar load is transferred, she returns to the field to gather more nectar. This process can be observed in an observation hive if one is available. Often the foraging bee is surrounded by several bees ready to receive the nectar. Usually the receiving bee will manipulate this small nectar load in her mouthparts. She will unfold and refold her proboscis exposing the nectar to the air circulating within the hive. During this process more glandular secretions are added by the bee. Thus as the nectar is exposed to the air of the hive it slowly thickens and is then suspended from the upper surface of a cell wall where it will continue to lose moisture (dry out so to speak). When the moisture content has been reduced to 18.6% or so, the honey is ripe and is capped over by the bees.
I had not given much thought to how much nectar a bee hive must gathered to produce one pound of honey, but the question was asked recently. Since nectar comes from many sources, it is impossible to say with a great deal of accuracy without knowing the exact sugar content of the nectar. However, a few percentages may be helpful for you to realize the amount of work required by the bees. If a plant has a 40% sugar content -- then in order to produce one pound of honey, the bees will need to collect two pounds of nectar. And if a plant is producing nectar with a sugar content of 20%, then four pounds of nectar will be required to produce one pound of honey.
Assignment: Make a list of flowering plants in your neighborhood. Observe which are visited by honey bees. Record dates of your observations and whether the bees are active or not. One way to do this is to time your observations so that your data has some means of comparison. For example, During a three minute observation of a single flower, how many bees visit that flower? You may find that no bees visit the flower you are watching. Record it anyway. Be sure to include time of day in your data. If you have access to a microscope, it would be good to take a look at the pollen grains produced by the plants you observe. Can you distinguish by color alone what pollen the bees are carrying in the pollen baskets? This project should be extended out over the flowering period of all plants in your neighborhood.
Example format: (you may choose any format -- this is only a suggestion.
Flower Date of Obs. Time of Obs. Location of flower Bee visits Pollen color
Dandelion 4-11-03 1:00 p.m. my back yard 3 in 5 min. yellow
What have we learned:
References for Further Reading:
Topics to explore:
Pollen is an integral part of a honey bee colonies nutrition. Pollen is a complex material providing food (proteins etc.) for young brood. A shortage of pollen will cause a hive to decrease in bee population and eventually cause the death of the colony.
- The pollen grain is the male part of the fertilizing unit.
- When pollen is gathered from the flower of the collecting bee gets much of the pollen all over the body hairs. This is scrapped off using a comb and rake on the legs. At the same time the pollen is mixed with a small amount of nectar used by the bee to pack the pollen in the pollen baskets.
- The pollen grain has a strong coating to protect the nucleus and its nutritive matter inside from all sorts of extreme environments thus the existence of fossilized pollen grains which allow the identification of plant species that grew many millennia ago.
- Pollen is a source of protein and varies in two ways:
First -- Total protein content is calculated by measuring the amounts of nitrogen in the sample. This is referred to as "crude protein."
Second -- The amino acid content of pollen varies from one plant species to another. Some pollens provide a balance of amino acids ideally suited to the bee's requirements while other pollens are missing one or more of the amino acids and thus are of limited value to the honey bee.
- Pollen supplies minerals, vitamins and some fats for the bee's diet.
- Pollen has only a small amount of carbohydrate and thus is not a source of energy for adult bees. Honey is a carbohydrate and thus it provides adult honey bees with the energy to fly and exist.
- Fresh pollen has the highest level of nutritive value. Once stored it begins to deteriorate. If you are collecting pollen and want it to be viable for the longest period of time, you should freeze dry it.
- Air dried pollen must be kept in air-tight containers and not exposed to moisture. Otherwise, pollen will develop a musty smell and mold will grow in it.
- Bees will compact pollen in cells with their heads. This pollen is often covered with honey and capped over. It is then used by the bees when needed.
- Pollen grains of the same species and of closely related species tend to be alike and the degree of their similarity is a measure of the closeness of relationship.
Some Scanning electron microscope images of pollen. These images were taken from Pollen Grains of Canadian Honey Plants published by the Canadian Department of Agriculture and Agri-Food which has one of the best guides to pollen identification that I have seen.
Two
views are shown in each set of photographs. The left side photos show the
end view of a grain of pollen. The right side views are side views of a
grain of pollen. Pollen grains vary in shape, size, and various features.
These are examples from the family
Acer Better known as Maple
These are examples from the family
Cichorium Better known as chicory
These are examples from the family
Helianthus Better known as sunflower
The price of this book when purchased was $57.00 U.S. when purchased in 1995. I do not know if the book is still in print. One might try:
Canada Communications Group -- Publishing Ottawa, Canada K1A OS9
If you are serious about this topic and want to identify pollen grains with a microscope, this book is invaluable.
Canada and the United States make limited use of pollen grain analysis because pollen content is mot part of the honey grading regulations. However, Europe, the Middle East and Asia do examine lots of imported honey. Thus if selling honey for foreign trade, if a honey is listed as clover, it must contain a percentage of clover pollen grains of more than 70%.
Have any of you watched Forensic Files on TV? There is a science of identifying pollen grains found in almost any sample that might be examined. The pollen helps the scientist understand where the pollen grains originated. This can get very exact -- Almost down to the exact geographic location.
This
is a sample of pollen in honey.
This honey sample has three different identifiable pollen grains in it plus some additional particles which can be found in honey. It is 1/3 sunflower (Helianthus), 1/3 basswood (Tilia), and 1/3 Rape (Brassica).
What are some other things found in honey?