Can Wild Bees Take Sting From Honeybee Decline?

John Roach
for National Geographic News
October 20, 2004

Decades of disease and overuse of pesticides have put the squeeze on populations of the domesticated honeybee. As a result, farmers are increasingly left with fields of flowering crops that fail to bear fruit.
Since some 15 to 30 percent of the food we humans eat directly or indirectly depend on the pollination services of bees, scientists say the problem threatens to take some excitement—and potentially abundance—from our diets.

Claire Kremen, a conservation biologist at Princeton University in New Jersey, thinks native wild bees can take some of the sting from the honeybee decline. These wild bees buzzed North America for thousands of years before the domesticated European variety arrived.

“We need to ensure we can keep on having [honeybees] around, but at the same time we can reduce the risk of relying on honeybees for crop pollination by protecting wild bees and ensuring their pollination services can be maximized,” she said.

Sweat bees like this one are small wild bees that usually go unnoticed, but can provide an important contribution to crop pollination. With honeybee populations falling, some biologists and farmers are concerned about insufficient crop pollination, a primary service that honeybees perform. Wild bees, however, may help decrease the level of unpollinated crops, as the mites that seriously harm honeybees don’t affect wild bees.

Photograph courtesy USDA-ARS/Scott Bauer
Funding for this Earth-systems science story was provided by the National Science Foundation.
This special series of news stories is produced as a complement to Pulse of the Planet, a daily sound portrait of the Earth broadcast on radio.

Scott Hoffman Black is executive director of the Xerces Society, a Portland, Oregon-based invertebrate-conservation organization. He says North American farmers rely so heavily on domesticated honeybees today that they often forget that pollinated food crops existed before the domesticated honeybee was introduced.

“Prior to the advent of large-scale monoculture agriculture [the practice of growing only one kind of plant in a given plot] in the fifties and the use of lots of chemical pesticides, native bees and feral honeybees pollinated everything. It wasn’t an issue. People didn’t cart bees all over the country,” he said.
Kremen and Black’s organization are collaborating to spread the word about the role wild bees play in crop pollination.

While they acknowledge that farmers cannot and will not revert to pre-1950s practices for the sake of wild bees, they advocate steps to conserve and use native wild bee populations as an insurance policy for when a honeybee shortage would otherwise leave fields sapped of their full potential.

Wild Bee Needs
Scientists estimate there are about 4,000 different species of wild bees that are native to North America. They nest in thick grass, soil, and wood; are rarely kept in hives; and generally do not make surplus honey or form large colonies.

While the mites that have proven so devastating to domesticated honeybee populations cause little effect to the wild bees, pesticide use and habitat loss are taking their toll, according to Black.

“Like any animal, native bees need a place to live,” he said. “They need nest sites and floral resources, and if they don’t have them, they won’t be there.”

According to Black, people can take small steps to augment wild bee populations, such as making nesting areas available. Given that about 70 percent of wild bees nest directly in the ground, not in hives, this is simpler than it seems, he added.

Wild bees also need natural habitat to forage, which can include small woodlots, areas along a stream, or even a hedgerow between fields of crops. As an added bonus, Kremen said, wild bees help keep wild areas healthy.

“They help us maintain the natural landscape, which provides spiritual beauty, recreational quality, and other ecosystem services we depend on,” she said.

Viable Populations?
Kremen has been documenting the extent wild bees play in crop pollination in California and has found that on farms in narrow valleys surrounded by wild vegetation the native bees can do most of the work.

But this is the exception, not the rule. The bulk of California farms are sprawling monoculture fields in the central valley that are completely devoid of natural bee habitat, meaning that wild bees will never be able to provide all of a farmer’s pollination needs.

“In most of the central valley—no way. The bee populations are not healthy enough,” she said. “There’s a dramatic decline in bee diversity and bee abundance when you go from the narrow valleys to the wide central valley.”

Robust wild bee populations do not thrive in the central valley’s monoculture fields. But Kremen said small improvements could allow some native bees to flourish, as long as larger source areas are also restored and protected. These small steps could include reintroduced native vegetation to areas around tractor sheds and irrigation ditches.

“If you can get 10, 20, 30 percent of your needs met by wild bees, that would help a lot,” she said.

Conservation Biologist: Best Job in the World?
Claire Kremen is a conservation biologist at Princeton University in New Jersey whose aim to make a real difference in the conservation of biodiversity. National Geographic News recently asked her a few questions about her job.

How did you get into the field of conservation biology?
I did my doctorate in zoology, in very basic science—development and evolution. But just as I was getting my degree, I started to feel that there was little point in studying fundamental evolutionary processes if most species were being rapidly doomed to extinction or a marginal existence with little evolutionary future.
I switched to conservation biology, which had just become its own discipline several years before.
The way I did it [was] teaching [Duke University’s] first course on the topic as a naive graduate student [and] volunteering to work on a conservation project in Madagascar that led to the creation of the Ranomafana National Park.

What is the best thing about your job?
The opportunity to make a real difference in the world.

Why is your job important?
Fifty to one hundred years from now, our descendants will either bless or curse us for how we have handled the biodiversity crisis today. Estimates of the magnitude of species extinction vary greatly, but one thing is clear: Current rates of extinction far exceed those of past extinction spasms. Largely, this is due to human influence.

Human-caused extinctions terminate the existence of countless organisms that evolved over hundreds of millions of years, and in doing so also threaten the life-support systems on which we depend.

What should tomorrow’s conservation biologists be doing today?
I could write a book about this. Today’s—and tomorrow’s—conservation biologists need to start from the on-the-ground problems and work back to the science, instead of the other way around.

In other words, they need to identify a real conservation need, determine what scientific information is required to help resolve the need, collect that information, synthesize and analyze it, and then apply it—or bring it to the attention of policymakers who can.

In general, conservation biologists need to work more closely with conservation managers and policymakers, and they need to get their findings out into the public view.

Finally, we need a better integration of social, anthropological, and economic dimensions into conservation biology. The original conceptualization of the field included all of these components, but ecological studies have in fact dominated the field.

We certainly need to understand the ecology better to get the job done, but it’s the marriage of the ecology and social/economic dimensions that will make practical advances for conservation on the ground.


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