California Coast & Ocean

Although most of the U.S. Department of Agriculture’s $9-million bee research program is devoted to issues concerning honeybees, researchers at its Bee Biology and Systemics Laboratory in Logan, Utah, study other bees in North America, all but one species native--their dispersal and diseases, as well as how they can be managed for crop pollination. Entomologist James Cane helps farmers build up and manage populations of various native bees for pollination, and to improve land-management practices so as to encourage more bee visits--for example, by maintaining habitat for wild bees and guiding insecticide use with bees in mind. Right now he is looking at bees in the genus Osmia (there are about 140 species just in the United States) because many should be relatively easy to manage, and they pollinate a variety of crops. He’s found that Osmia aglaia, a cavity-nesting bee, for example, is a good, readily managed pollinator for raspberries and blackberries. He is helping two California start-ups build up to mass production of Osmia lignaria, the aforementioned blue orchard bees, for almond pollination.

Cane also works with alfalfa seed growers in the Pacific Northwest, who he says have had tremendous success managing alkali bees and alfalfa leaf-cutter bees to pollinate their crops. “There are 17 million nesting alkali bees in 60 square miles of Washington State, with some individual aggregations more populous than for any other bee on the planet,” all managed by private alfalfa growers, he said. “When you get down to ground level, you can’t even see through the bee bodies; it looks like heat waves. It’s just dizzying.”

Bee-Friendly Practices
Given the right conditions, wild bees could provide more of the pollination needed by agricultural crops. On farms that can attract a diverse and abundant population of wild bees, they can pollinate even such demanding crops as watermelon, which requires several insect visits, studies by University of California, Berkeley assistant professor Claire Kremen have shown. Now Kremen is involved in a habitat restoration effort on farms in California’s Central Valley that may help increase populations of wild native bees.

The Valley can be an inhospitable place for bees. Many of the farms there are conventional, growing one crop at a time with a lot of chemical inputs, whereas bees prefer floral variety and are highly sensitive to chemicals. Nevertheless, Kremen is optimistic that the landscape can be made more friendly to pollinators. In collaboration with Audubon California, the Xerces Society for Invertebrate Conservation, USDA’s Natural Resources Conservation Service, and the Center for Land-Based Learning, she is adding bee-friendly plants and practices--such as providing buffer strips and hedgerows around fields and planting cover crops--to riparian restoration projects on six conventional farms in Yolo County. Her research has shown that the food resources for bees on or near a farm are more important to their survival than whether or not the farmer uses pesticides. “We think we can make a pretty big difference by providing a variety of floral resources for the bees,” she said. If monitoring shows these practices are successful, the partners plan to help spread them to other farms in the Valley.

The Xerces Society and the Natural Resource Conservation Service are already working to include pollinators in programs that provide incentives for farmers to practice land stewardship and conservation. Implementing conservation projects on their land is “a lot of extra work for growers to take on,” said Mace Vaughan, Xerces’ conservation director. “We have to make sure there are as many reasons for them to do it as possible. Pollinators are one great reason.”

Meanwhile, Gretchen LeBuhn, an assistant professor of biology at San Francisco State University, is helping vineyard owners make their land more pollinator-friendly. The extensive destruction of oak woodlands to make way for vineyards in Napa and Sonoma Counties has fragmented bee habitat and meant a big loss of food resources for pollinators. But LeBuhn has found that vineyards can be made more inviting to bees by planting certain kinds of native plants in gardens or as cover crops and making sure that flowers are available to bees from spring through early fall. She also suggests tilling carefully--less often or less deeply, or leaving some areas untilled--to avoid disturbing the nests of ground-nesting bees, and putting native plants in available niches, such as along farm ponds. She has collaborated with several wine-grape growers on her research and has been invited to speak to groups of vineyard owners interested in adopting sustainable practices.

As meadows, fields, and woodlands continue to disappear, LeBuhn thinks urban parks and gardens might also be important habitat for native pollinators. “The potential is huge,” she said. Two of her graduate students have studied bee populations in San Francisco’s parks and natural areas to determine which characteristics are most important to the types and numbers of bees the parks support. One student tallied 70 species of native bees in 24 natural areas--an amazing number, considering San Francisco’s urban density, though fewer than the 87 species noted in historical records of the California Academy of Sciences.

In 2008 LeBuhn will launch “The Great Sunflower Project,” handing out sunflower seeds and seedlings to people and organizations around the San Francisco Bay Area who agree to plant them and record bee visits. “It really will contribute to our understanding of where bees are and how dense they are,” she said. “What we’re looking at [in all these projects] is how we can take lands that are being used by people and give them more resources for wildlife.”