Multiple causes could make it extremely difficult to stop the decline of the bees. If so, farmers may have to embrace a change in strategy and encourage the assistance of alternative pollinators like solitary wild bees and bumblebees. A promising study published last autumn by ecologists Sarah Greenleaf of the University of California at Davis and Claire Kremen of the University of California at Berkeley found that the presence of wild bees increases the efficiency of sunflower pollination fivefold. “You see these female bees with these huge loads of pollen on them, dive-bombing the honeybees on the flowers that the wild bees want to be on,” says Greenleaf. Being bumped off one flower seems to prompt the honeybees to move the pollen from the male plants over to the female plants—which is exactly where the farmer needs it to go.
Greenleaf and Kremen counted 33 species of wild bee in the sunflower fields of Central Valley in California. These bees nest in underground tunnels or hollow twigs in nearby natural habitat—oak woodlands and chaparral, or dense shrubland. But such lands are under serious threat from giant single-crop farms. “These big giant monocultures pretty much hammer the bee habitat,” says Mace Vaughan, an entomologist and conservation director of the Xerces Society in Portland, Oregon, which promotes insect biodiversity. “If you go from the foothills of the coast range in California and go out into the heart of the Central Valley, the bee diversity and abundance just steadily drops off.”
One solution is to enhance the habitat for native bees around farmland—by planting hedgerows, for example, or leaving some land uncultivated. Vaughan cites research that Canadian canola farmers who sow seeds on only 70 percent of their land (leaving the remainder as wild habitat for native bees) are more productive, and make more money, than those who plant the crop on all of their fields. Another approach is to encourage managers of semiartificial environments like golf courses to surround the greens with the types of plants, like sunflowers, lupines, and black-eyed susans, that attract native pollinators.
Jim Cane, an entomologist at the U.S. Department of Agriculture Bee Biology and Systematics Lab in Utah, is working on ways that wild bees could replace honeybees on some crops, rather than merely supplementing them. Bumblebees are already raised commercially for pollinating greenhouse tomatoes. Cane has successfully raised a range of native bees for other kinds of commercial use. Leaf-cutter bees and alkali bees pollinate alfalfa, the blue orchard bee pollinates fruit trees (especially almonds), wild bee species Osmia aglaia and O. bruneri pollinate raspberries and blackberries, and O. ribifloris is effective at tending to blueberries. In most cases, managing these bees means providing habitat in which they can nest, like drilled wooden boards or hole-studded stone blocks for cavity-nesting species like the blue orchard bee.
Replacing honeybees with wild bees is not as simple as it sounds, however. Many wild species specialize on one or two crops, and they can be expensive to raise. By contrast, says Cane, “The honeybee is a jack-of-all-trades. You can plop them down in mustard, in apples, in blueberries, whatever crop, and they’ll visit and give you pollination. With honeybees, you can provide hundreds of thousands of foragers very cheaply—less than a penny a forager.” All the more reason, then, to be concerned about their disappearance. Yet Cane remains skeptical about the severity of CCD. “Clearly, some beekeepers have had some disasters this winter, and I do feel for them,” he says. “But the magnitude, extent, scale, and certainly cause are still open questions.”
One big block in understanding what is happening to the bees is a lack of hard data: Many states in the past decades have dismantled their apiary inspection programs. “Bean counters said, ‘Well that one job, that’s a lot of money we could save in our budget, nobody’s clamoring for it, so let’s just jettison it,’ ” Cane says. Had inspectors had the opportunity to examine commercial hives across states, “we’d be six months ahead of where we are now.”
Meanwhile, ordinary people can help keep pollinators abundant. For example, they can scatter hole-punched bee blocks in their gardens in which wild bees can nest. Vaughan of the Xerces Society encourages planting lots of backyard flowering plants that bloom year-round. “But the best thing for the average Joe to do is reduce or eliminate his or her use of pesticides around the house,” he says. “These kill more good pollinators than bad things.”