Intimate Portraits of Bees

Bees are the workhorses of the insect world. By transferring pollen from one plant to another, they ensure the next generation of the fruits, nuts, vegetables, and wildflowers we so enjoy.

There are 4,000 species of North American bees living north of Mexico, says Sam Droege, head of the bee inventory and monitoring program at the U.S. Geological Survey (USGS).

Only 40 of them are introduced species, including the European honeybee. (See “Pictures: Colored Honey Made by Candy-Eating French Bees.”)

Most of the natives are overlooked because “a lot of them are super tiny,” Droege says. “The bulk of the bees in the area are about half the size of a honeybee.”

The native species also go unnoticed because they don’t sting, he adds. They quietly go about their business gathering pollen from flowers in gardens, near sand dunes, or on the edges of parks.

The bee pictured above is a species of carpenter bee from the Dominican Republic known as Xylocopa mordax. It nests in wood or yucca stems, and is closely related to the U.S. species that chews through the wood in backyard decks.

Droege and colleagues began to inventory all the bee species in North America in 2001. This was partly because the insects are so important to the agriculture industry.

“Almost all the fruits and nuts, and a lot of the vegetable varieties, that we eat require some insect—usually bees—for pollination,” he explains.

The crow bee (Halictus ligatus) pictured above favors sunflowers and black-eyed Susans, Droege says. “That yellow pollen is almost for sure sunflower pollen.”

“East of the Rockies, [the bee is] everywhere,” he adds. “They’re very common in urban areas and disturbed sites.”

And that’s the second reason why Droege carries out his bee inventory—because the insects are an important component of the landscape. Knowing how bee populations are faring is important when monitoring the health of those urban and otherwise vulnerable environments. (See “The Plight of the Honeybee.”)

Finding out after the fact that “all the bees are gone and now we’re screwed,” says Droege, is not what he wants to see happen.

But to complete the bee inventory, the biologist and his colleagues needed to identify exactly which species were being sent to them by researchers from around the country.

That’s easier said than done, because so many of North America’s native bee species are so small.

Even those with some experience could look carefully and say at most, “yes, that’s a little bee,” Droege explains. “There are maybe five people in the U.S. who could identify bees.”

Rather than compiling a physical collection of identified bees—which not everyone would be able to come and examine—Droege decided to do the next best thing: He started a photo catalog of bee species.

It was a while before Droege could produce detailed images like the one of a honeybee’s head (Apis mellifera) pictured above. (See also“Fuel Exhaust Disrupts Scent Signals for Honeybees.”)

He spent years “floundering around with okay pictures,” he says, and trying to compile identification guides. But the wildlife biologist knew he needed a better system.

Enter the U.S. Army.

Tony Gutierrez, a molecular biologist with the U.S. Army’s Public Health Command in Maryland, had devised a camera system in 2008 that enabled soldiers in far-flung places to take detailed pictures of biting insects.

Disease is a great concern for the U.S. Army, says Gutierrez, and his job is to identify pathogens like malaria that are found in arthropods like mosquitoes. (See “Mutant Mosquitoes Not Repelled by DEET.”)

Catching an insect suspected of biting an ill soldier, and trying to identify it, was laborious and not always accurate, says Gutierrez. There are about 80,000 species of mosquito in the world, but only a handful bite and transmit disease.

Identification guides used at the time by soldiers in the field were more suited to experts already familiar with the insect groups.

“That wasn’t really working well for the soldiers who were relatively new to this,” Gutierrez says. When asked what would make their lives easier, the soldiers said “just give us a picture.”

Four years ago, Gutierrez came up with a system that consisted of a camera fitted with a macro lens, a mount with a slider, and digital software suitable for stitching pictures together.

Taking images at the level of magnification needed for bees or mosquitoes meant that there was absolutely no depth of field, says Droege. Only portions of an insect would be in focus at any one time.

So if researchers or Army personnel wanted a picture of an insect that was completely in focus, they would have to take several pictures—each one focused at different points—of the specimen and combine the photographs for one in-focus image.

Mounting a camera with a macro lens on a slider programmed to step through those various focal increments enabled anyone to take the photographs.

When Droege and Gutierrez teamed up several years ago and the USGS biologist got the first bee picture back from Gutierrez, “it was mind-blowing,” Droege says.

“The pictures are so detailed, they create a virtual museum for these specimens,” he says. A scientist could use the images to really drill down to the level of detail needed to identify species.

Once Droege trained sufficiently on the system to build his own setup, he started making pictures and posting them on the photo-sharing site flickr.com in 2010.

The bee pictured above, known as Augochloropsis sumptuosa, is a sand specialist, he explains. “It hangs out [on the] sand hills of North Carolina. You’ll see them on the Eastern Shore in the dune areas.”

This species forages for pollen from flowers located on the edges of those sand dunes.

This species, known as Anthophora affabilis, inhabits Badlands National Park in South Dakota. Its tongue, sticking down to the left, is a drinking straw combined with a tongue, says Droege. “It’s a two for one.”

The bee uses it to reach into the necks of trumpet-shaped flowers to retrieve the nectar lying at the bottom, he explains.

The bee can suck up the nectar through the “straw” while tiny hairs along the tongue enable it to lap up leftover bits of nectar and pollen.

Droege has learned over the years to pick his photography subjects—such as this very common bumblebee (Bombus griseocollis)—with care.

“Originally, I’d grab whatever specimen we had at hand,” he says. “[But] almost all bees have a lot of hair,” and the capture and preparation processes usually left a lot of them looking a little worse for the wear.

Droege and colleagues dry and prepare their bee specimens as best they can, and use Photoshop afterward to remove from the image any large specks of dust that remain.

They also erase the pin supporting the specimens from the image and then sharpen and crop the picture.

Droege adds that he doesn’t manipulate the colors in his images. “Scientifically, that’s not the point.

“Those bees are those colors,” he says. “[And] many of them are naturally iridescent.”

This bee, known as Augochloropsis metallica, is one such example. Related to the A. sumptuosa that lives in sand dunes, A. metallica is a more common find.

“It was collected by a guy in our office who was working on bumblebees,” says Droege. “He collected [the bee] off a tomato plant in his backyard.”

This species, a Hylaeus modestus captured near Washington, D.C., is half the size of a grain of rice. The head is so small that Droege needed to use an acupuncture needle to mount it for imaging purposes.

“Unlike other bees, instead of carrying pollen on the outside [of its body], they ingest it and carry it internally,” the biologist explains. They then regurgitate it back at the nest when they provision their eggs.

Since the bee photographs were originally intended for a scientific audience, Droege and colleagues include shots like this one of an isolated head, in case researchers need detailed views of certain body parts.

But last fall, Droege got a message from both of his daughters that someone had taken several of the bee pictures from his flickr.com site and posted them to a section of the popular website Reddit.com called woahdude.

“In two days [the post] had 200,000 views,” he says. Normally, Droege can’t get very far at parties once people find out that he studies bees. But now, the “general, general public,” he says, was marveling over the images.

“Once you blow [the bees] up to the size of a German shepherd and they have good hair, people start paying attention,” he says. “They’re like aliens from another world.”

Πηγή: National Geographic