Growing Magazine - March, 2011
The California Agricultural Pollinator Project
Tracking CCD, honeybees and native bees
Honeybees and native bees were more abundant when agriculture was practiced on a smaller scale," says Mace Vaughan, an entomologist who has led The Xerces Society's Pollinator Conservation Program since 2003. In areas where smaller farms border flower-rich, diverse habitat, for example, the Capay Valley in Northern California, and southeast Pennsylvania, wild native bees and bumblebees still pollinate all the crops. The varroa mite decimated feral honeybees in the mid-1990s.
A native leaf-cutter bee collects pollen from blanket flower.
PHOTO BY MACE VAUGHAN, THE XERCES SOCIETY.
On midsized farms bordered by diverse landscapes, wild native bees and bumblebees provide significant pollination along the edges. On large-scale farms, however, wild pollinators are a lot harder to find, either because their habitat has been lost or because of pesticide treatments. Although growers successfully imported commercially raised honeybees for decades, these bees are still threatened by Colony Collapse Disorder (see sidebar on bees).
The California Agricultural Pollinator Project is a collaboration among several organizations, including The Xerces Society for Invertebrate Conservation in Portland, Ore., a nonprofit named for the extinct butterfly, the Xerces Blue, that works to protect wildlife and help farm production by bringing bee habitat back to the farm. These organizations aim to bring wild bees back.
The short-term goal is to plant existing conservation buffers with vegetation designed to support pollinators. The long-term goal is to have hedgerows scattered on farmland, with diverse, plentiful flowers and bee habitat for nesting, egg-laying, overwintering and as a refuge from pesticides.
"The heart of this project is to get pollinator habitat into the ground and protect it," says Vaughan, who also serves as the joint pollinator conservation specialist for the USDA's Natural Resources Conservation Service. "We're asking farmers to plant a diverse habitat, a whole new crop on their land." There are beneficial side effects of this plan. Plantings that attract pollinators attract songbirds and insects that eat pests. Pollinators also can recolonize degraded agricultural areas.
The origins of the project go back to 2003, when Professor Claire Kremen of UC Berkeley was researching the role the natural habitat plays in supporting native bees and crop production, and Audubon California's Landowner Stewardship Program was implementing stream restoration projects throughout Yolo County in the state.
"We worked with them to fine-tune the plant lists," Vaughan says. "It's a buffet of plants chosen based on Claire's work."
They collaborated in planting a pollinator habitat demonstration hedgerow at The Farm of Putah Creek in Winters, Calif., the home base of The Center for Land-Based Learning, and began to incorporate pollinator conservation measures into the restoration projects.
Farm Management Tools
- Set aside marginal areas and work with your neighbors to protect natural
areas around your farm.
- Plant diverse plants in hedgerows and along streams.
- Plant native plant species. Many hybridized varieties have been bred for
showy flowers at the expense of nectar and pollen.
- Allow flowers to bloom in natural areas, field and road edges and gardens,
especially when crops are not blooming.
- Allow crops such as lettuce, kale, basil and broccoli to bolt, to supply
bees with nectar and pollen.
- Plant cover crops, such as canola, buckwheat, phacelia and clovers.
- Avoid grazing animals during peak flowering time, from early spring to
early fall, and take grazers off a site as soon as they have finished eating
the grasses they prefer before they start to eat wildflowers.
- When doing prescribed burning, rotate burnings and burn no more
than 30 percent of a site in any one year.
- Mow in fall or winter. Mow patches over several years instead of an
entire site all at once. No single area should be mowed more than once
- Rather than applying blanket sprays to an area, spot treat weeds and
insect pests. Use targeted ingredients (for example, Btk to kill leaf rollers),
large granules and the least harmful formulations. Spray insecticides
on dry evenings soon after dark. Avoid spraying butterfly host
- Minimize tillage to protect pollinators that live underground. Keep dead
trees standing to provide shelter for species that live in tree cavities.
In 2006 (according to the Xerces website), they joined forces with the USDA's Natural Resources Conservation Service (NRCS), which was already planting buffers to control erosion and improve water quality in streams.
"If you're going to plant a buffer to save a stream bank, you might as well choose the best plants to support native bees and honeybees on adjacent farms," he says.
The NRCS has been a tremendous partner. "They really like how pollinators can serve as a framework to do more ecologically focused restoration work on the ground. We help them pick which plants encourage beneficials, hold soils and prevent fertilizer from getting into streams."
This work is further encouraged by two acts that came out of the 2008 Farm Bill, Vaughan says, and in which The Xerces Society was fundamentally involved.
The Pollinator Protection (Research) Act authorized research into problems facing bees: Colony Collapse Disorder in honeybees, as well as the decline of native pollinators in North America. "One of the best outcomes was the Specialty Crops Research Initiative, which made the roles of native bees on pollination one of its biggest priorities."
The Pollinator Habitat Protection Act "made pollinators a priority resource concern for the Farm Bill's conservation programs," he says. "The conservation work is almost all administered through the NRCS, as well as all the technical support and some financial support."
Wild native bees have lived in the U.S. for thousands of years. There are approximately
4,000 species, and all but 40 to 50 species are solitary. They make individual nests
in tunnels underground and in dead trees.
"You may find thousands of nests in one area," entomologist Mace Vaughan says.
Most are females, who do most of the pollination work because they provide for the 30
to 40 offspring they produce. They eat only pollen and nectar, and need an abundance
and variety of flowers throughout the growing season.
Native bees are more versatile than honeybees. Some are active when conditions are
too cold or wet for honeybees. Many are more efficient at moving pollen between flowers.
Several species "buzz pollinate" flowers: They vibrate the flower to release pollen
from deep inside the anthers. Some plants, including tomatoes, peppers and cranberries,
require buzz pollination.
Honeybees are a major part of modern agriculture. "They were brought to the U.S. in
the 1600s and were most important for honey and wax until the 1950s or '60s," he says.
"Then agriculture became larger and more intensive, and farmers had to rely more and
more on honey bees for pollination."
European honeybees are the only bees in North America that have large, perennial
colonies, make honey and swarm to reproduce. Living in close quarters made them
susceptible to the varroa mite, "a sort of a vampire mite," he says, that came into the
U.S. in the mid-1980s. By 1995, the mite had wiped out all the feral honey beehives, and
it is still around.
Vaughan believes that Colony Collapse Disorder is a result of honeybees first being
weakened by stress, pesticides and limited diet, and the virus and fungus combination
may deal the deathblow.
Bumblebees are also important pollinators, he says. "They nest in cavities about the
size of a softball. They're often larger and fuzzier than other bees, so they can forage
earlier and later in day, when it's cooler. On a bee-for-bee basis, they can be a hundred
times more efficient at foraging than honeybees."
The project and its cooperating farmers also receive financial support from the Agricultural Wildlife Conservation Center, USDA's Sustainable Agriculture Research and Education program, a number of private foundations and conservation programs including the Environmental Quality Incentives Program, Wildlife Habitat Incentives Program, Conservation Stewardship Program and Conservation Reserve Program.
Jessa Guisse, The Xerces Society California habitat restoration specialist, teaching a workshop on pollinator hedgerow creation at the USDA-Natural Resources Conservation Service Plant Material Center in Lockeford, Calif.
PHOTO BY CHRISTINA SMITH, USDA-NRCS.
Xerces is taking the pollinator project nationwide and providing help to at least 35 states. In Pennsylvania, for example, 130 acres of pollinator habitat are going into the ground in the next few months. They're also looking at areas in the Midwest, and at the Central Valley in California, where they're designing existing buffers to support pollinators.
"It's exciting for me," Vaughan says. "These ideas have really resonated, and this work is really rewarding. The number of scientists studying native bees has more than tripled in the last five to eight years. What I'm hoping we come away with is an integrated system where we're able to rely on a wide variety of bees for farm pollination."
The author is a freelance writer based in Altadena, Calif.