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What's happening to the bees?

Suddenly, the bees farmers and growers rely on are vanishing. Researchers are scrambling to find out why.

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A review of honeybee history shows many suspects. The Varroa mite, native to Asia, came to North America in the late 1980s. Since then, yearly losses of between 15 and 20 percent have become the norm. "Before the mites, you could be a bee-have-er," says Mr. vanEngelsdorp. "Now you have to be a bee-keep-er."

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Beekeepers are the first to acknowledge the stress of migratory pollination. Carted on flatbed trucks from wintering sites in the South, the bees crisscross the continent, first to California's almond groves, which rely entirely on honeybees for pollination, and then northward throughout the country, following the spring flowering season. Farmers have come to rely increasingly on honeybee services, says May Berenbaum, head of the department of entomology at the University of Illinois, Urbana-Champaign. "Given its economic importance, beekeeping really hasn't gotten the attention it deserves," she says.

Poor nutrition may be another factor, says Mr. Vaughan. To prepare them for winter, bees are fed high-fructose corn syrup and protein supplements. In the fields they've pollinated, meanwhile, more often than not they've gathered only one kind of pollen. Maybe, like other animals, they need a diverse diet, he says. "If you only ate McDonald's every day, you'd be just like that guy in 'Super Size Me,' " he says. "And he didn't feel that good."

Others, like Doan, suspect pesticides.

Similar problem in 1990s France

In the 1990s, France experienced a precipitous honeybee decline from "mad bee disease." Honey production dropped by nearly one-third, to 25,000 tons. French beekeepers blamed a newly introduced pesticide marketed under the name Gaucho. From the same family as nicotine, the chemical targeted aphids' navigational systems. And when the honeybees weren't finding their way home, either, French beekeepers protested. The French government banned the product in 1999. Though subsequent studies haven't found a strong link, bee populations still haven't rebounded to previous levels.

Others point to genetically modified crops – specifically, those with a gene for a bacterial toxin called Bt. Initial studies indicated that it didn't affect bees. But some beekeepers argue the trials didn't last long enough to determine the long-term effects. (Doan says the same about the nicotinelike pesticides.) A German study supports this. Scientists at the University of Jena found that while Bt food had no direct effect on bees, when fed to bee populations infected with parasites, they quickly became diseased. Alone, Bt may do nothing. But in the presence of a parasite, it may facilitate infection.

"Maybe these toxins weaken the immune system," says John McDonald, a retired biologist and hobby apiculturalist in Spring Mills, Pa., who wrote an editorial on the topic for the San Francisco Chronicle

But the shrinking of our so-called "pollination portfolio" is of more concern to many entomologists than a die-off in commercial beehives. A 2006 National Academy of Sciences report declared that there was "direct evidence for decline of some pollinator species in North America" – species responsible for pollinating three-quarters of flowering plants. Europeans have documented a parallel decline in their natural pollinators for years.

On the US East Coast, where a more ecologically diverse farming landscape enhances species diversity, studies have shown that wild pollinators were doing about 90 percent of the pollinating anyway, says Neal Williams, an assistant professor of biology at Bryn Mawr College in Pennsylvania. "It seems a little bit silly from a whole-country perspective, even from a farmer perspective, that we would place so much emphasis on one species. We don't do that with any other part of the economy," he says.

Meanwhile, a Canadian study suggests that if canola farmers leave 30 percent of their land fallow, they will increase their yields. Wild land provides habitat for native pollinators, improving pollination and increasing the number of seeds. "If we cultivate all the land, we lose ecosystem services like pollination," says Lora Morandin, lead author on the study. "Healthy, sustainable agricultural systems need to include natural land."