By Sasha Ingber via nationalgeographic.com
Not every bee may count, but Sam Droege is counting every bee.
On Saturdays, the head of the landmark Native Bee Inventory and Monitoring Program at the U.S. Geological Survey leaves his straw-bale house, where bees burrow in the walls, and goes to his office—for pleasure. From his desk, a recycled segment of a lane from a bowling alley, he pores over bee specimens with a microscope.
“I’m looking deeply into [their] eyes to see what they reveal,” said Droege. “I’m looking for species in potential trouble, gathering information on their status before they’re designated an endangered species.” (See “Intimate Portraits of Bees” for more of Droege’s bee pictures.)
Droege is pioneering the first national inventory of indigenous wild bees, a task of growing importance. The buzz started in 2006 when honeybees, the non-native species used commercially to pollinate crops, began to mysteriously vanish after leaving their hives. If honeybees continue to wane in coming decades, scientists believe wild bees could save our crops. (See “The Plight of the Honeybee.”)
Problems for Pollinators
More than half of managed U.S. honeybee colonies have disappeared in the past ten years. Though native to Eurasia and northern Africa, honeybees pollinate a third of the American diet, from nuts to produce—not to mention coffee and cotton. In 2010 they contributed to more than $19 billion worth of crops. (Related: “U.S. Honeybee Losses Not as Severe This Year.“)
Pesticides, fungicides, and viruses, among other factors, have contributed to the honeybees’ decline. Though they lack a traditional vertebrate circulatory system, they’re vulnerable to parasites, such as the bloodsucking varroa mite, which deforms their bodies and shortens their life span.
Little is known about the hardiness of the honeybee’s native counterpart, the mostly solitary wild bee. Many scientists believe that wild bee populations were once greater, but have dwindled as land was developed and agriculture intensified.
Home gardeners may also be contributing to the bees’ habitat loss. Gardeners with a love of exotic plants often uproot native ones, not realizing that this deprives most pollinators of their food. Other factors limiting the bees’ food supply include the effects of climate change, droughts, floods, and flowers blooming prematurely as the days grow warmer.
The Bees in Our Backyard
“People were collecting bees in the early 1900s, but they weren’t doing quantitative analyses,” said Georgetown University biologist Edd Barrows.
In 1998, Barrows gathered bees in Dyke Marsh Wildlife Preserve in Alexandria, Virginia, using mesh, tentlike structures called Malaise traps. The bees he collected then—still awaiting examination due to lack of time and funds—could serve as a historical reference point to show scientists how the preserve’s bee fauna is changing due to water and air pollution, erosion, and invasive plants.
“We need to have some way of measuring whether native bees are increasing or decreasing,” said Droege.
His own survey methods are unconventional, albeit familiar to scientists on shoestring budgets. To collect bees, plastic party cups act as pan traps. (Droege says the idea stems from the 1970s, when butchers gave their customers yellow pans, which people would fill with soapy water to catch bugs outside.)
Workers from New Horizons Supported Services, an organization that helps adults with developmental disabilities in Maryland gain employment, paint the cups to mimic the colors bees prefer in flowers. Then the cups are filled with propylene glycol—the same substance used to maintain moisture in food, medicine, and cosmetics. Its low surface tension means that insects will sink to the bottom. Every two weeks, the traps are emptied by volunteers.
After that the bees are washed, dried, and stored at the USGS lab in repurposed pizza boxes. Their deaths serve as a chance to learn about, and monitor, potentially endangered native bee species.
The biggest problem is telling the bees apart. Bees are often difficult to differentiate, and about 400 species—ten percent of North America’s bees—lack names. (Compare that to the 1,000 ant species that have been named.)
“[They're] not something someone like a birder could look at, and say, ‘That’s a robin,’” said biologist Daniel Kjar of Elmira College in New York.
So Droege spends hours trying to identify species. His team captures the pitting on their skin, the striations of hair on their abdomens, and other physical traits with a macro lens camera—a sort of insect portraiture. Droege says these body features may help bees avoid predation and attract mates.
Harvesting the Unknown
Today, scientists will go to great lengths to study the small insects.
Sean Brady, head of the Smithsonian Institution’s Department of Entomology, is studying evolutionary relationships between different bee species. He’s sequencing their genetic material, which can cost between $10,000 and $50,000 for a complete genome.
He’s also interested in understanding why, among certain bee species that produce offspring twice in a season, the first brood spends its lifetime caring for the second hatching instead of reproducing. The work may help him understand the social behavior and pollination strategy of wild bees.
“The unknown can be a good thing,” said Brady. “There is a lot to learn in the next 10 to 20 years.”
In 2010 and 2011, Brady and Droege set up traps in the cacti and thorn scrub of Guantanamo Bay, where the native habitat is preserved in the midst of the prison camp. They collected more than a third of the bee species that live on the entire island of Cuba. A new species they discovered was quickly named—Megachile droegei, after Droege.