New bees on the block
Boosting native bee populations could give beleaguered honeybees a break.
Fri, Mar 27, 2009 at 03:46 PM
Illustration: Josh Cochran
Honeybees play a vital role in American agriculture—they pollinate one-third of all our crops. But in 2006, colony collapse disorder hit nearly a quarter of US commercial beekeeping operations, which lost between 50 and 90 percent of their hives. The cause of the die-offs remains unknown: Suspects include pesticides, parasitic mites, and a virus.cause of the die-offs remains unknown: Suspects include pesticides, parasitic mites, and a virus. Though pollination nearly returned to normal in 2007, the crisis of the previous year highlighted agriculture’s overreliance on honeybees. That’s where Butler Farm comes in. “We’re interested in increasing biodiversity without sacrificing farm production,” says Rominger, who has been farming for 27 years.
Researchers on the farm are trying to boost dwindling native bee populations by providing habitat for them to live in. Traditionally, agriculture has relied on honeybees imported from Europe because they live in hives, can be easily transported, polliate in large numbers, and produce honey. Unlike honeybees, all but 45 of the 4,000 native bee species in North America are solitary, nesting in tiny holes in timber or the ground. Some native bees are generalists—they’ll eat nectar and pollen from a variety of plants—while specialists rely on a specific plant or group of closely related plants. On the Butler Farm and six other sites, scientists are attracting a variety of native bees by planting 1.5 miles of hedgerows made up of 25 species of plants that bloom in the spring, summer, and fall. In addition to preventing soil erosion and shading streams, the hedgerows provide abundant pollen and nectar for crop-pollinating bees. Interspersed in the hedgerows are blocks of wood with holes and bare patches of earth for nesting.
Increasing the numbers of native bees isn’t an instant solution to our honeybee woes, but it will help solve some of the problems. “We know that it’s probably not going to be the case that almonds in gigantic fields are going to be pollinated by native bees,” says Neal Williams, a biologist at Bryn Mawr College. “But knowing where native bees can provide pollination might allow us to take pressure off the need for as many honeybees.”
Researchers around the world are trying to determine whether their regions’ native bees can pollinate blueberries, squash, and dozens of other crops. So far, results have been encouraging. For example, the bees increase the quality of cherry tomato and coffee crops. And when it comes to pollinating sunflowers, native bees actually make honeybees up to five times more efficient. Researchers believe the native bees’ presence makes honeybees skittish, causing them to move from male to female sunflowers, pollinating more seeds.
Yet many native bee populations have suffered declines, in large part due to habitat loss and destructive agricultural practices. The insects are most productive and abundant on farms with natural areas, such as forest fragments, less than a half-mile from the edges of fields. The varied landscape provides nesting habitat and diverse floral resources.
Claire Kremen, an ecologist at the University of California, Berkeley, has found that farms in New Jersey have diverse and abundant wild bee populations. Farmers there tend to plant multiple crops, and there are patches of natural habitat nearby. The same isn’t true in California, where the land was transformed to grow acre after acre of one type of crop. In these areas, large crops like almonds are pollinated by commercial honeybees that are trucked in. “The problem with monoculture cropping is that for a few weeks there’s a massive bloom, but the rest of the time there’s nothing for bees to eat,” says Kremen. “Coupled with habitat loss, it’s not very good for native bees.”
Kremen is working with the conservation group Xerces Society and Audubon California on the Butler Farm project. “We want to see, if we restore habitat for these bees, can we bring the bee communities back to healthy condition in areas that were degraded?” she says. The groups surveyed the areas before planting hedgerows and will monitor them over the next three years as plants mature and bees colonize the nest sites. Ultimately, they hope to calculate the dollar value of the increased crop pollination that comes from restoring bee habitats.
It’s too early to determine whether native bee populations will rebound. But researchers and farmers are optimistic about what they’ve seen so far. “In some of the newly planted areas, there are a lot of bees flying around,” says Katharina Ullmann, California Pollinator Conservation Coordinator of the Xerces Society. “It’s really buzzing, in terms of the numbers and kinds of bees.”
Story by Alisa Opar. This article orginally appeared in "Plenty" in January 2008.