As I mentioned in an earlier post, pollen is virtually the only source a colony has for protein, lipids, vitamins, and minerals. Colonies that pollinate large monocultures—such as almonds—have a severe lack of variability in their diets. Just as one fruit or vegetable doesn’t satisfy all your nutritional needs, one type of pollen is not enough for the bees.
Pollen from different flowers varies tremendously in both the quantity and quality of protein. Researchers have found that the protein content can range from about 2 to 61% by dry weight. Furthermore, some protein may lack some of the amino acids necessary for proper growth and development.
An example of a poor pollen source is the common dandelion, Taraxacum. Bees seem to love dandelions, and are often seen going from blossom to blossom in large numbers. But dandelions are missing some of the essential amino acids. Research has shown that a diet of pure dandelion pollen will hinder larval development in mason bees, prevent brood production in honey bees, and cause 100% larval rejection in bumble bees.
In nature, monocultures aren’t much of a problem. A bee would seldom—if ever—run into an endless monoculture of dandelions, and so they don’t cause a problem. But bees plunked down in the middle of acres and acres of a single crop will have a problem nourishing the next generation. And even if the young bees survive and mature, their immunity to diseases and parasites may be compromised. Just like any other animal, bees need healthy immune systems to survive, and healthy immune systems depend on proper nutrition.