for National Geographic magazine
What's causing the unprecedented decline of millions of honeybees? This mystery has been vexing some of the world's best scientists ever since U.S. beekeepers began noticing enormous numbers of their bees dying off or vanishing for no apparent reason several years ago.
Honeybees contribute some $15 billion to the U.S. economy every year, pollinating 90 major crops, everything from fruits to nuts. Most of us take these foods for granted, rarely realizing the vital role tiny creatures play in making them thrive.
Put simply, says zoologist Martin Wikelski, "Everything depends on pollinators."
That's one reason this leader in the study of small-animal migration has begun examining the mostly unknown universe of bee movement.
Wikelski is pioneering the use of supersmall radio tracking tags that fit on the backs of bees, a technological breakthrough that may provide him and other scientists with a direct view of the pollinators' flight patterns.
This could someday help them understand what's causing the honeybees' decline—and how to harness other kinds of bees to protect food supplies.
Until now, tracking insects such as bees has proved difficult. They fly too far too fast to be chased on the ground, and they're too small and nimble to monitor from the air.
Bumblebees, for instance, cruise at 20 feet (6 meters) per second, says Rutgers University entomologist Rachael Winfree, who's working with Wikelski on the bee-tracking project.
As a result, scientists are largely in the dark about basic questions involving bees' movements.
Most estimates of how far bees range when foraging are based on indirect tests such as removing bees a set distance from their nests to see if they return. "The assumption," says Winfree, "is that the only way bees know where they are is because they have an internal map of the area, created when they flew there before. If displaced outside their mapped area, they can't navigate."
But since some bee species are known to find their way back home from as far as 12 miles (20 kilometers) away, some scientists speculate the insects can also follow odor or magnetic gradients—or maybe they simply get lucky and find the nest as they buzz around aimlessly, Winfree says.
SOURCES AND RELATED WEB SITES