The Beekeeper’s Companion Since 1861
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The Curious Beekeeper

On the Trail of a Pollen Tramp

- April 1, 2018 - Rusty Burlew - (excerpt)

Loose Pollen Bee on Flower

Here is the problem. Over there, just beyond a tall hedgerow, is a vast field of wildflowers. Many of those plants need insect pollinators to move their pollen from flower to flower. Over here, just outside your garage, is a thriving honey bee colony with lots of brood to feed. Pollen is an essential part of the honey bee diet, so the bees crave it.

What you have is a biological logistics problem. The flowers have the pollen and want to distribute it. The bees need the pollen and want to acquire it. The problem is how to effect a fair and equitable transfer of goods and services.

Bees and Flowers are Tight

During eons of evolution, bees and flowering plants evolved systems that complement each other. Since plants can’t walk, jump, hop, or swim, they developed ways of tricking insects into doing the work for them. Even though sweet nectar, alluring odors, and attractive flowers are biologically expensive for the plant to produce, pollination by bees is more reliable than simply relying on the wind. Furthermore, it requires far less pollen. Even accounting for the pollen the bees steal, flowering plants benefit greatly from insect pollination.

While we normally think of honey bees collecting nectar, an average-size colony may accumulate 125 pounds of pollen in a season.1 From the bee’s perspective, pollen is a rich source of protein and other nutrients including vitamins and minerals, lipids and fats. It’s also a relatively safe type of food to collect. Since pollen does not fight back, it is a lot easier to collect than insects or spiders. So while the plants became more attractive to bees, the bees developed methods of collecting, carrying, processing, and storing the pollen.

Honey Bees are Adaptable

Many species of bees have a one-on-one association with a particular species of plant, while other bees forage from a closely-related group of plants. But honey bees are polylectic, meaning they forage from a large variety of plant species. The European honey bee was introduced into North America, South America, Australia, New Zealand and other regions without missing a beat. The flowers in each place were different—not at all what the honey bee evolved with—but it didn’t matter. Her adaptations for finding, collecting, and storing pollen and nectar worked well even for plants she had never seen.

That’s not to say that honey bees forage and pollinate all flowers with the same degree of success. They don’t. For example, flowers requiring buzz pollination, such as tomatoes, are not pollinated by honey bees. And some plants with complex flower parts, or barely sweet nectar, do not attract honey bees. 

DNA Wrapped in Color

Pollen grains are designed to protect the plant’s genetic material as it is transferred from one flower to another. In order to assure the genetic message is not scrambled in transit, or destroyed completely, the DNA is locked inside several secure layers.

At the very core of the pollen grain, the genetic package floats in a pool of cytoplasm, which is protected by a layer of cellulose called the intine. The intine is protected by another layer called the exine.2 The exine is very tough, resistant to things like uv radiation, moisture, dryness, pressure, and changes in pH. As you can imagine, the exine is not easily breached.

Finally, the exine is wrapped in a super-sticky and colorful layer called pollenkitt.3 Pollenkitt keeps the pollen from blowing away from the flower, but it also allows the honey bee to clump pollen together into those hard pellets packed on her back legs.

One of the first things a new beekeeper notices is the rainbow of colors on a honey bee’s hind legs. The corbiculae, often called pollen baskets, are found on the outside of each hind tibia and comprise a wide spot surrounded by stiff hairs.

Depending on your area, pollen loads come in multiple shades of ….