Submitted to the HMEG Blog by Elaine Evans
While most people are familiar with honey bees and their amazing behaviors and hive products, many do not realize that honey bees are not native to North America. Honey bees were brought to North America by European settlers. There are, however, around 20,000 other species of bees worldwide, most of these living a solitary life nesting in the ground or in plant stems. Around 4,000 of these bees are native to North America with around 300 in Minnesota. These bees range widely in size and color, from big fuzzy bumble bees, to tiny metallic green sweat bees. They all rely on nectar and pollen from flowers for food.
Pollinators are responsible for 35% of crop production worldwide. The value of U.S. crops that rely on pollination is valued at over $18.9 billion. Of 100 crop species that provide 90% of food supplies, 71 are bee-pollinated, mainly by wild bees. A simple way to think about this is that pollinators are responsible for roughly one in three mouthfuls of food and drink we consume.
With the advent of large-scale agriculture, human society became reliant on one bee species, the European honey bee, for pollination of our crops. Increasing farm size, with decreasing wild lands surrounding these farms, has reduced habitat for native bees. For these large-scale farms, native bee populations are typically not strong enough to provide the needed pollination services. Honey bees are brought in by commercial beekeepers to pollinate many crops.
Considering the importance of crop pollination to the integrity of our food supply, it is astounding that we rely on one bee species. Sadly, it has taken severe losses of honey bee colonies over the last several decades to increase awareness of this problem. Honey bee declines are due a variety of diseases, pests, parasites, and pesticides combined with the stress created from the pressure to provide pollination services to gigantic monoculture crops. Most commercial beekeepers are migratory, moving bees from one crop to the next across the United States. Bees from all over the county are brought together to pollinate specifics crops, such as almonds in California, oranges in Florida and cranberries in Wisconsin. The bees mingle on the flowers and pests and diseases are shared. Poor nutrition, pesticide exposure and diseases, pests and parasites all combine to make it very difficult for honey bee colonies to survive.
While all bees are exposed to the same threats such as lack of flowering resources and nesting habitats, pesticide exposure, climate change, diseases, pests and pathogens, bee species vary in their responses to these threats. Some species are clearly in decline while others are stable. Honey bees are a unique case as there are not many wild colonies in North America. Basically, all honey bee colonies are managed by people. As such, their populations are dependent on beekeepers. Beekeeping has become much harder due to declining honey prices and the costs of coping with diseases and parasites afflicting honey bees. Since the 1950s, there has been a 50% decline in the number of managed honey bee colonies. Rather than saying that honey bees are in decline, I would say that bee keeping is in decline.
Native bee declines are most likely due to habitat loss and pesticide exposure. Other possible causes include climate change and novel diseases or pests transferred from honey bees or other commercial bee operations. Unfortunately, we don’t know enough about most of our native bees to even really be sure that they are in decline.
If every bee on the planet died tomorrow, we would not starve. Wind pollinated crops, such as rice and wheat and corn, are significant portions of our diets. Many other plants can reproduce without the help of pollinators. However, the quality of our diets would severely decline. Nutritionally, we would be hard set to find good sources of many vitamins that are essential for our health, such as vitamin C. Most fruits and nuts would not be available.
Pollination is often called a keystone ecological process. This means that many other organisms are dependent on the pollination services bees provide. Many plants cannot reproduce at all without pollination. Herbivores depend on those plants for survival, and in turn, carnivores depend on those herbivores. Besides the grave impact on the quality of our food supply with pollinator decline, there is whole chain of organisms that will suffer if bee populations decline significantly.
There are some important things that you can do to help native bees. Plant a garden with lots of native wildflowers. Many hybrid varieties of flowers don’t produce nectar and pollen, so natives are best. Having large patches of the same kind of flowers helps attract more bees. Plan to have something always blooming between April and September. Ground nesting bees use bare soil for nesting, so leaving bare patches of soil is helpful. Stem nesting bees will use pithy stems so don’t cut all your stems down in the fall. Let them stay there as long as you can stand to see them, but at least until the following May. If there are clovers and dandelions in your lawn, let them bloom to provide nectar and pollen. My favorite bee flowers are bee balm, anise hyssop, new england aster, cup plant, leadplant, lupines, wild indigo and purple prairie clover.
Keeping honey bees is a great way to learn about bee biology, provide pollination for your garden and produce your own honey. There is a great class taught at the University of Minnesota every March and October. More info here: http://www.extension.umn.edu/
There are simple nest boxes that can be made to encourage native bee nesting too. More info here: http://www.xerces.org/