Bipolar Flora and Fauna

(Click on the picture to lift your mood.)

Actually, the title has nothing to do with mood swings, but rather with the fact that both the pictured bee and plant are friendly at one end and deadly at the other.

In the honeybee, the bipolarity is easily perceived. This worker bee is sipping nectar from which to make delicious honey—for the hive and for us. At the other end, however, her modified ovipositor is ready to inflict pain, inflammation—and for the allergic, threat of death.

The plant is the Spotted Knapweed. What could be bipolar about a scrawny, insignificant-looking weed? Even the flowerhead, enlarged and beautified in the photograph, is actually small and far from being a showcase in the meadow. But at least it is secreting some nectar for the benefit of bee nutrition.

It’s the “other end” of the knapweed that provides the "depressing" side of the story. Its roots secret a deadly herbicide called catechin to kill competing plants, allowing the knapweed to take over acres of ground, including grazing land for cattle.

So what seems like a simple flower and bee story turns out to be a veritable biochemistry textbook! Here are some of the main characters:

*Anthocyanin pigment in the flower petals, used to attract the bee. See Queen post for some anthocyanin chemistry.

* Nectar secreted by glands in the bases of the knapweed florets as a reward for the bee. It consists of simple sugars (monosaccharides), including glucose and fructose, as well as a small percentage of sucrose (disaccharide), a host of minerals, enzymes, volatile oils and vitamins. Nectar is very dilute, but back at the hive it gets concentrated to less than 18% water content by evaporation (worker bees beat their wings to death doing that).

*Catechin, secreted by the roots of the knapweed. It’s a natural herbicide that is as effective as 2,4-D (See here) and is used by the knapweed to kill its competition for space. The question is: why doesn’t the stuff kill the knapweed? The plant is clever enough to secrete the compound as fast as it makes it, not allowing it to build up its own roots—and by blocking its re-entry. There is a tremendous amount of sophisticated cell physiology going on. The other side of this story is that there are different forms of catechin. The other forms include wonderful anti-oxidants found in tea! Here is a health food store’s worth of information.

*Apitoxin (bee venom) secreted by glands in the tail end of the bee, consists of a complex mixture of proteins and is similar to snake venom. It causes local inflammation and is an anti-coagulant. When as little as a tenth of a milliliter is injected under human skin, it causes pain, blasphemous utterances—and in the approximate 1% of victims, who are allergic, anaphylactic shock and possible death. Of course, the pictured friendly honeybee is not likely to attack (The only time I have been stung by a honeybee is when I stepped on one). It’s another story with Yellowjackets and White-faced hornets!

What a Gilbert's Chemistry Set of diverse compounds is produced by cells in the two ends of two of God’s creatures! What blessings and curses the minor tweaking of molecular structure may produce! What stories may be told of biology before and after Man’s fall into sin and the resultant curses, as related in Genesis 3!

Soli Deo Gloria!