Pollen and Honeybees

By: H. Wayne Shew, Ph.D.
NAB Certified Pollen Counter

Insects are the most important group of animals in regards to pollination of flowering plants.  Bees, including bumble bees and solitary bees play significant roles in flower pollination, but the most important insect in pollination is the honeybee.  There are a number of reasons why bees make good pollinators.  1) They have hairy bodies to trap pollen as they move from flower to flower.  2) They require a large amount of nectar and pollen to feed their young and thus visit large numbers of flowers.  3) Bees concentrate their pollination efforts on one species of plant at a time and thus function as very effective pollinators.  4) Bees have a body size that makes it possible for them to pollinate a variety of flower sizes and shapes.  5) Bees will often fly long distances to collect nectar and pollen and thus can serve as effective pollinators of plants that are not located close to the hive.

Honeybees typically collect nectar and pollen when visiting flowers.  They also visit some flowers from which they only collect pollen and some flowers from which they only collect nectar.  Nectar is a watery substance that contains various sugars (fructose, glucose, and sucrose being the dominant types).  The bee collects nectar and stores it in a special stomach to carry it back to the hive.  After processing of the nectar in their stomach they regurgitate it into cells in the honeycomb.  Bees then reduce the water content of the nectar in the honeycomb by fanning their wings over the cells.  Flower nectar is a thin, easily spoiled liquid, but once processed by the honeybee it becomes a stable, high-density, high-energy food.

We typically think of honey as a natural liquid sweetener composed of water and various sugars, in fact, it is “a highly concentrated water solution of two sugars, dextrose and levulose, with small amounts of at least 22 other more complex sugars.”  Honey contains other substances besides sugars including: flavoring materials, pollen, pigments, minerals, and organic acids.  These minor constituents of honey are chiefly responsible for the differences seen among individual types of honey with regard to flavor and color.

Pollen is incorporated into honey in various ways.  Some pollen falls into the nectar being collected by the bee and ends up in her honey stomach and is then transported back to the hive where it along with the nectar is deposited in a cell of the honeycomb.  Other pollen grains will stick to the hairs on her legs, antennae, and other body parts which might then be deposited in cells of the honeycomb as she grooms her body to remove entangled pollen.  Some worker bees collect pollen for the hive by depositing pollen in an area on their hind tibia called a pollen basket.  (See image below.)  This pollen is deposited into special comb cells and in the process some can fall into open cells of the honeycomb containing nectar or honey.  Honey may also contain pollen from plants that are wind pollinated.  This pollen can blow into the hive and directly into cells of the honeycomb or be picked up by bees as they enter the hive and then be accidentally deposited into cells.  The pollen present in honey can be used to determine the sources of the nectar used to make the honey; for example, clover honey should have a predominant amount of pollen from clover flowers.  This can be of particular importance commercially because honey made from some plants commands a much higher price than others (citrus, sourwood, tupelo, etc.).  Honey sold as made in the U.S.A. should not contain pollen produced by flowers not native to the U.S., if it does then it indicates that the honey is adulterated with honey produced in another country.   The combination of the types of pollen present in honey from insect and wind pollinated plants will often produce a pollen spectrum that is unique for a specific geographical area.

What benefit do bees obtain from the pollen they collect?  Dry pollen is an important food source for bees.  Pollen will have a protein content of 16-30%, 1-10% fat content, 1-7% starch, and many vitamins.  The principal source of carbohydrates for developing bees if of course the honey they produce.  It is estimated that in order to rear one worker bee from the larval to adult stage requires 120-145 mg of pollen.  A typical bee hive will collect some 44 to 125 pounds of pollen each year; that’s a lot of pollen being moved around by honeybees.  No wonder honeybees are such important plant pollinators and one of the insects we should be happy to have in our yards, fields, and forests.

Some interesting facts about honeybees:

  1. Bees are the only insect in the world that produces food which humans can eat.
  2. Bacteria cannot grow in honey because of natural preservatives and its low water activity.
  3. Each colony of bees has a queen that is responsible for laying eggs.  She will lay around 1,500 eggs each day.
  4. Worker bees are always female and perform all of the work of the hive; cleaning, feeding young bees, feeding and caring for the queen, packing pollen and nectar into honeycomb cells, building and repairing honeycombs, etc.
  5. Bees collect nectar, pollen, water, and a sticky substance called propolis (propolis is a sticky tree resin obtained from tree buds or bark and is used as a bee glue to seal and strengthen the hive).
  6. Bees have two stomachs—one stomach for eating and the other for storing nectar collected from flowers or water that is then transported back to the hive.
  7. Bee’s wings beat some 200 times per second, 12,000 beats per minute.  They can fly about 15 mph.
  8. It takes about 2 million flowers to make one pound of honey and this amount of honey requires the work of about 556 worker bees to gather the needed nectar.
  9. The average worker bee will make about 1/12th of a teaspoon of honey in her lifetime.
  10. The average honey bee lives three to six weeks during the working season.

(These interesting facts from http://www.ontariohoney.ca/kids-zone/bee-facts).