It’s hard to open a newspaper or magazine these days without seeing an article about the decline of bees and the subsequent effect on our food crops. The ecological service that pollinators provide is necessary for the reproduction of more than 85 percent of the world’s plants, including more than two-thirds of the world’s crop species. Some crops, including blueberries and cherries, are 90 percent dependent on bee pollination.
Several factors contribute to declining bee numbers. For one, the U.S. has seen a major decline in the practice of keeping bees. “Since 1945, we have seen about a 50 percent decline in the number of managed honeybees in the United States,” says Eric Mader, national pollinator outreach coordinator at the Xerces Society. (If you have an interest in beekeeping, join our beekeeping community at Keeping Backyard Bees.) Meanwhile, the number of planted crops that require pollination has nearly doubled during the same time period.
Pesticides pose another problem. “Beekeepers are reporting massive die-offs in their hives or situations where bees simply don’t return,” says Brian DeVore, communications director of the Land Stewardship Project. “In addition, many species of native pollinators, such as various types of bumblebees, are endangered,” he says.
The class of pesticides known as neonicotinoids is suspected to be one of the major causes of bee die-offs. The pesticides, nicknamed “neonics,” were introduced in the 1990s and have become the most widely used insecticide in the world—so ubiquitous that they are now found in 80 percent of the world’s crops. They come coated on virtually every seed planted in every major crop across the country—sunflowers, canola, cotton, soybeans and corn, for example. Neonics are systemic; they are taken up and move freely through the entire plant making every part of it toxic. When ingested, the compounds can cripple a bee’s navigational skills and its ability to find its way home after foraging. They may also interfere with a honeybee’s intricate “waggle dance” that tells other bees where to find flowers. Neonics can also undermine bees’ immune systems.
A recent study from the Harvard School of Public Health demonstrated that neonics are likely responsible for triggering colony collapse disorder (CCD) in honeybee hives that were healthy prior to the arrival of winter. Last year, Europe adopted a three-year moratorium on neonicotinoids. Cities in the states of Washington and Oregon have enacted similar bans. Last fall, Home Depot announced it would require labels on plants containing neonics, and the Minnesota Legislature recently passed a law forbidding nurseries to put “bee-friendly” labels on plants containing the pesticide. The U.S. Fish & Wildlife Service announced that neonics will be banned in the 150-million-acre National Wildlife Refuge System by January 2016.
And there are still more reasons for the decline in bee populations: loss of floral diversity and habitat due to urbanization; expansion of intensive agriculture; invasive plants; climate change; disease; and parasites. The changing face of agriculture results in a flowerless monoculture of cash crops. Farmers once grew sweet clover and alfalfa to add fertilizer to the soil. Now much of the Midwestern landscape is an agricultural desert of corn and soybeans—plants that don’t feed bees. Synthetic fertilizers have replaced natural ones, and the widespread use of herbicides has virtually wiped out the milkweed, clover and wildflowers that once grew in farming regions. In suburban areas, millions of acres of grass offer no nutrition for bees. Bees are left to forage in smaller and smaller areas—wildlife preserves, state parks and strips of untended land between roads and fields.
Honeybees aren’t alone in pollinating crops. In North America, the 4,000 types of native bees are in many ways superior pollinators to honeybees. For example, unlike honeybees, bumblebees will fly in bad weather. To pollinate an acre of apples requires 40,000 honeybees—or 250 orchard mason bees. “Seventy percent of our native bees nest in the ground,” Mader says, “and crop tillage—cultivating fields for weed control—has a devastating effect on these native bees.”
Mader sees the most striking declines in native bees among bumblebees. Bumblebees have a unique ability to perform “buzz pollination” where they grab a flower and literally shake pollen loose from the flower. This is the only way tomatoes can be pollinated. “Bumblebees are significantly more efficient pollinators than honeybees, particularly for things like cranberries, blueberries and tomatoes,” Mader says. “When Europeans settled North America, there were about 45 bumblebee species on the continent, and in the past decade or so, we’ve seen dramatic declines in those bumblebees. At present, about 30 percent of North America’s 45 bumblebee species are at risk of extinction.”
So what can we do to help the bees? First, we can completely eliminate our use of pesticides such as neonics. Although many pesticides’ and herbicides’ labels say nothing about their toxicity to bees, all insecticides can kill bees. Even some products such as rotenone and spinosad, approved for organic gardening, are a danger to bees. Consider using floating row covers or planting pest-resistant varieties instead of using pesticides. Don’t buy any plants, including houseplants, treated with neonicotinoids—ask nurseries and look for those that grow their own organic plants without pesticides.
• Plant in clumps of four to six plants, not just singletons.
• Bees seem to prefer blue, purple, white and yellow blossoms, so plant anise hyssop, annual lobelia, flax, heliotrope, lavender and lupine. Choose flowers of various shapes and heights for bees of different sizes and body shapes. Single flowers have more pollen and nectar than double flowers, so consider black-eyed Susans, California poppies, coneflowers, cosmos, sunflowers and zinnias.
• Bees need reliable water sources. Somewhere in your garden, provide a shallow bee bath. Add flat stones so bees can drink without drowning.
• Researchers at North Carolina State University have discovered pollinators prefer visiting plants grown in soil where compost, rather than commercial fertilizer, has been used.
• If you live in corn country, plant tall shrubs or other borders around the garden to keep pesticide drift at bay.
• Rethink your idea of a perfect, tidy garden so there’s room for bees to make their homes. Leave a little corner of your yard undisturbed for a bee nesting habitat. Seventy percent of bees nest in the ground rather than a hive, and a small area of open dirt in a sunny location is ideal for these ground-dwelling bees’ nests.
• Plant native flowers or heirloom varieties. Modern cultivated hybrids have less pollen and nectar.
• Give up a manicured turf lawn. Instead include dandelions and clover, both excellent nectar and pollen plants for bees that also make nitrogen available for other plants. Plant flowering cover crops such as buckwheat early and late in the season to provide food for bees when they need it. If you can’t provide a natural nesting site, build a bee condo.
Despite all the bad news about bees, Marla Spivak, director of the University of Minnesota Bee Lab, says she is optimistic. “The word is out that our pollinators are in trouble, and from where I sit people are engaging to help bees, monarchs and other pollinators,” she says. “Five years ago these issues were not on anyone’s radar. Minnesota is leading the nation in legislative initiatives to help pollinators, and the White House released their national strategy to help pollinators this summer.”
Joe Pye weed
Does buying organic food benefit bees?
Organic agriculture ensures plants are not treated with synthetic pesticides, which can be toxic to bees. Some organic pesticides can also be harmful, but generally organic farmers use fewer pesticides and organic farmers tend to grow a diversity of crops, rather than monocrops. Crop diversity means the habitat will have more ground space for nesting native bees, more flowering plants and better landscapes to support bee biodiversity.
What about supporting local beekeepers—would that help?
The best way to support beekeepers is to plant more flowers for bees, and to keep those flowers free of pesticide contamination. We all want clean food, and so do bees.
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