APRIL
2003

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

04-24-03

Bees and Flowers Play the Pollination Game

Flowers and bees! Bees and flowers! No matter how you look at it, you really can't separate the two. In the natural order of things, bees depend on flowers and flowers depend on bees.

This flower and bee thing is what scientists call mutualism. It is a partnership where both participants benefit from the association. So how does it work?

Like a lot of things in nature, it all boils down to reproduction. One of the most common reproductive approaches used by plants is based on seeds. Production of seeds begins when pollen from the male parts of a plant contacts the female parts of a plant. Then some X-rated things happen involving pollen tubes, styles and other plant parts. Ultimately, a seed develops.   

If both the male and female parts are from the same plant, the process is called self-pollination. If the male and female parts are from different plants, that is called cross-pollination. Cross-pollination is good since it results in gene mixing and what has come to be known as hybrid vigor in the offspring.  

Plants, unlike animals, can't go searching for mates. Instead, plants just send their pollen in search of mates. Send may not be the correct word. The pollen has to be transported. Sometimes the pollen is carried by the wind. Other times pollen is carried by insects.

Several groups of insects transport pollen from flower to flower. Beetles, butterflies and wasps have been shown to carry pollen. However, one group of insects, the bees, are the premier pollen bearers of the insect world. Unlike other insects that transport pollen by accident, the bees do so intentionally.

Bees and flowers actively play the pollination game. The process is one of the miracles of nature. But neither the flowers nor the bees play the game just for fun. We're talking serious biological business here. The flower has a job that needs to be done. It needs pollen transported. The bee needs food to feed its family. This is the biological version of "Let's Make A Deal!"

Flowers produce a fine quality food called nectar. This sweet substance is utilized by many insects.  Unlike other insects, bees have developed a process to refine and store nectar as honey.

So what we have here is a classic economics problem. Flowers have a raw material that is needed by bees. But economics teachers warn that you can't stay in business if you sell products below costs. This is true of flowers. So nectar is bartered. Bees provide a pollen transport service in exchange for nectar. In order to ensure that the bee carries out its part of the deal, the flower does not provide a full load of nectar for a bee. Each flower provides just enough nectar to entice the bee to feed. It must go to other flowers to complete the load. When that happens, pollen is transferred from flower to flower.

But in the rough-and-tumble world of business and nature, it is not enough to provide a wonderful raw material like nectar. The plant has found that it pays to advertise! Plants do so with flowers. The flowers function to attract the bees to the plant. Once there, the bee makes its way to the nectar distribution center. On the way, it crawls by the pollen-dusting facility where grains of pollen stick to hairs on its body.

So what if the bee seems to have been tricked into carrying the pollen for the plant? Remember, "All's fair in love and war!" And in pollination, apparently.

 

Writer: Tom Turpin
Editor: Olivia Maddox