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Pollen: a tough package wrapped in color

One of the first thing beekeepers notice about pollen is its color. Depending on where you live, pollen loads come in many shades of yellow, white, orange, pink, blue, gray, and purple. And because honey bees visit the same type of flower during any one foraging trip, the pellets on their legs are the same color throughout.

In any colony the nurse bees are the primary consumers of pollen. The nurse bees digest the pollen and then secrete “brood food” from glands in their heads. It is these glandular secretions that are fed to the larvae.

Digesting pollen

Digesting pollen, however, is no easy trick. The pollen grain is designed to protect the plant’s genetic material as it is transferred from one flower to another. In order to assure the genetic message doesn’t get scrambled in transport, it is locked inside several layers:

  • The genetic package floats in a pool of cytoplasm. This cytoplasm is the rich food source that honey bees require.
  • The cytoplasm is wrapped in a cellulose layer, called the intine.
  • The intine is wrapped in another layer, called the exine. The exine, made of something called sporopollenin, is designed to fend off environmental hazards like ultraviolet radiation, moisture, drying, pressure, and changes in pH.
  • The exine is coated with a sticky substance called pollenkitt. Pollenkitt is extremely sticky and enables the pollen to stick to flowers and not blow or wash away. It is also what allows honey bees to clump it together in their pollen sacks.

As it turns out the germinal pore, the place where the genetic material will eventually be released, is the weak point in the pollen grain. Enzymes from the honey bee gut make their way through this pore and are able to digest the innards…sometimes.

Researches who study bee waste find that not all pollen grains are digested. Fully digested grains look like popped balloons—everything is gone except for the deflated cellulose husk. Some grains are partially deflated and some are still whole, meaning that little or none of the nutrition was extracted from those grains.

Nutrition can vary

Digestibility and nutrient value of pollen grains is highly dependent on the species of flower that produced them. Foraging bees cannot tell how digestible or nutritious a pollen grain is just by looking at it, which is one reason why a varied diet is crucial to honey bee health.

Rusty
Honey Bee Suite

Honey bee collecting bluebell pollen. Flickr photo by OliBac.

Comments

Harry
Reply

You know Rusty, I loved this post so much that I blogged about it (as well as some other blog posts on the same topic) over on my own blog. Thank you for writing it. P.S. I’d like to learn what your thoughts are of my own blog post on the subject.

Nancy
Reply

Rusty – one of life’s great pleasures has to be learning things you didn’t even know were there to learn! Hey, just to know someone studies bee waste (nice phrase btw)! Then a question: what does this information do to people’s perception that pollen (and indeed almost any hive product) has some magic, mystical nutritional qualities? I mean if there’s pollen, and pollen, so to speak, surely its food value (?) for humans must vary quite a bit? thanks, as always, Nan

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