By JANET RALOFF
Most people in the northern half of the United States will remember the winter of 1996 for record snows that seemed to take forever to melt. Apiculturists, however, will remember it as the winter their bees died.
"We've been hearing regularly of people who lost 80 or 90 percent of their [commercial] honeybees," reports Anita M. Collins of the Agriculture Department's bee research lab in Beltsville, Md. Honeybees, the most versatile and widely cultivated of natural pollinators, play a pivotal role in the fruiting or seed development of numerous plants, including at least 30 U.S. crops valued together at about $10 billion annually, according to Roger Morse of Cornell University.
The shortage extends beyond the snow belt and managed bee colonies, observes Gary P. Nabhan, of the Arizona-Sonora Desert Museum in Tucson. In Arizona, for instance, "we've seen a 70 percent loss in [wild] honeybees since 1991," he says. Nationally, he reports, only about 2.7 million wild and managed honeybee colonies exist--fewer than half as many as 50 years ago. "And half this loss," he notes, "occurred within just the last 5 years."
The pandemic spread of two parasitic mites has fostered this decline in the honeybee population. "We know they are everywhere now in the United States," Collins says of the mites, and "perhaps one-quarter of the [bee] colonies have both."
The tracheal mite, which entered the United States from Mexico in 1984, burrows holes through the inside wall of a bee's windpipe to get at the insect's equivalent of blood. The Varroa mite, which entered the country 3 years later, attaches to the outside of the honeybee and sucks out this bloodlike fluid.
The parasites weaken, but do not kill, the honeybees. However, Collins says, new data suggest that they increase the insects' vulnerability to disease and early death.
In another 10 years, U.S. honeybees may become resistant to the mites, Morse predicts, just as their kin in Europe and South America have. For now, he says, "we're just squeaking through."
Indeed, bee nurseries weren't able to supply beekeepers with all the stock they requested this year, Collins notes. "So if we get a big kill like this next year," she says, "Lord knows what will happen."
The honeybee crisis "is part of a larger pattern of pollinator declines," Nabhan notes. A report he prepared last month lists more than 180 species of vertebrate pollinators--including geckos, hummingbirds, warblers, parrots, bats, weasels, and lemurs--that are threatened with extinction.
In The Forgotten Pollinators (Island Press, Washington, D.C.), to be published next month, Nabhan and pollination ecologist Stephen L. Buchmann of the Carl Hayden Bee Research Center in Tucson link falling numbers of these vertebrates, as well as insect pollinators other than bees, to two major phenomena: inadvertent poisoning with pesticides and human activities that fragment an animal's habitat.
At a press conference this week, the pair stated that funding is urgently needed to develop pollinators that can substitute in the near term for honeybees. They say that most of the pollination scientists whom they have surveyed agree.
Buchmann and Nabhan also suggest that national programs extend the protection given the habitats of endangered plants to the habitats of the plants' pollinators and that farmland retired under the conservation reserve program be planted with forages attractive to important pollinators.