The role of pollen in honey bee nutrition
In the back of the feed store, where pallets of fifty-pound sacks rise to the ceiling, I watched two women obsess over brands of layer ration. From what I could hear, they were concerned about protein content and they were comparing the nutritional labels. It makes sense. If you want healthy chickens and many eggs, your birds need a balanced diet that includes the proper type and amount of protein. It works the same way for horses, pigs, dogs, cats, and even your kids.
Although we often speak of the protein content of foods, it is the selection of amino acids that is most important. Proteins are made from strings of amino acids. When an animal needs a certain protein, it can take the amino acids it ate and string them together to build the protein. Even more awesome, if an animal eats one protein, it can take it apart and re-string the amino acids to make a different proteinthe one it actually needs. Conceptually, its a bit like Legos. You use single pieces (amino acids) to build the object you want (protein).
Honey bees, too, need the proper mix of amino acids to be healthy. Except for trace amounts in honey, pollen is the sole source of amino acids in the honey bee diet. And just as humans need a variety of foods to remain healthy, a honey bee colony needs a variety of pollen types.
Variety is important because not all the amino acids are found in a single type of pollen. Some have a greater assortment than others, so eating a variety of pollen types is the ticket to good colony nutrition. In nature, this would not be difficult. But in many modern settings, especially those containing a small number of flowering species, bees may come up short in one or more of the essential amino acids. Coming up short can mean diminished life spans, less resistance to disease, or poor foraging ability among other things.
Only in recent years has honey bee nutrition begun to receive the attention it deserves. As colonies came under attack from more threats, including new pathogens, parasites, and pesticides, it became clear that well-fed colonies with balanced diets had the edge over those with nutritionally deficient diets.
I learned many things while writing my paper for the UM master beekeeper program. But the thing that bowled me over was discovering that honey taken from healthy colonies shows more antibacterial action than honey taken from nutritionally deficient colonies. Why? Because bees receiving a full complement of amino acids are more able to secrete the enzymes that give honey those properties, especially glucose oxidase. And why is that important? Because that is the same enzyme that, when secreted into brood food, keeps the larvae free of disease. It that cool or what?
It is easy to fall into the trap of thinking that since our fathers, grandfathers, and great uncles never worried about bee nutrition, we shouldnt either. Back then, the bees gathered pollen on their own and thrived. No one gave two hoots about its source or amino acid content.
While that may be true, we have substantially changed our environment in the intervening years. No longer are urban areas separated by large swaths of natural vegetation. No longer do farms grow a large selection of crops. And no longer do roadsides provide a sparkling array of wildflowers. No. Instead we plant vast expanses of one thing and spray down the rest until the landscape is uniform and easy to manage. Bee nourishment? Who cares?
In this new world, beekeepers must be mindful of the pollen available to their bees. Ironically, if you live in an urban area with diverse plantings, your bees may be fine. But if you live in an agricultural area with monocrops, your bees may suffer. Most of us have something in between, but all of us need to be aware.
Depending on where you live, planting flowers or flowering trees may be the best solution. Others have worked at changing the spraying regimens in their local communitiessimply changing the timing of maintenance can make a big difference. Other beekeepers use pollen substitutes, or they trap pollen for feeding when local pollen is scarce. Others use bee vitamins added to syrup.
Certainly these measures are extra work for the beekeeper, but I think the resources used to prevent a nutritional deficiency can be offset by healthier, more productive bees. Typically, when we think of feeding bees, we think of syrup. Its high time we added pollen to the menu.
Image courtesy of honeybeesuite.com