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Bees are making headlines these days, and not in a positive way. Colony collapse disorder has cut through honeybee populations, with some beekeepers reportedly losing up to 90 percent of their stock in recent years. European bee populations are also declining, and so are some species of North American bumblebee. That data is often interpreted to mean that all of the world's 20,000 bee species are in danger, and that we may be in the midst of a "global pollinator crisis." But there's little data to back up those claims, scientists say.
"When you look at what's out there in the public press, the implication is that pollinators are all under threat, that there's some kind of mysterious decline across the board," says Sam Droege, a biologist at U.S. Geological Survey's (USGS) Patuxent Wildlife Research Center. "The problem is, there's really no data to show that either way."
A new paper, published in the Journal of the Kansas Entomological Society, offers a ray of hope for native bee species. In this research, Droege and his colleagues compiled a list of 770 species that are historically native to the eastern U.S. They sent this list to a network of bee experts, asking them to note which species they had found within the past 20 years. The survey revealed that 95 percent of the bee species that lived 150 years ago have not gone extinct. Thirty-seven species were nowhere to be found, but the researchers pointed out that those bees had been rare to begin with and were often subject to taxonomic confusion. The paper offers "a clarification to the 'all pollinators are going to hell' point of view," Droege says.
It is important to understand the health of our native pollinators, because "in the absence of pollination, whole communities could collapse," says USGS ecologist Ralph Grundel. "If plants can't reproduce, you lose the primary producers, and then the species that depend on them." It is also estimated that bees pollinate about a third of the food that we eat, at a value of about $15 billion per year.
Grundel, who was not involved in the research, said that the paper is a good starting point. "It's useful because they've put together this information on what was out there historically, and what still is out there. But the fact that they're not finding mass extinctions is not the equivalent of knowing whether species are declining or in jeopardy."
Droege, too, said that the conclusions are weaker than he'd like. "We'd love to make statements more detailed than, 'Yup, we found 'em!' But if we didn't do this paper, we basically wouldn't know anything at all," he says.
John Ascher, an invertebrate zoologist at the American Museum of Natural History (AMNH), agreed. He wrote in an e-mail that "we don't even know what native bees exist, as many remain undescribed or unidentifiable. Nor do we know where they live, as even state lists remain highly incomplete despite our best efforts…. As to how the bees are doing—we know even less."
In order to really understand the health of native bees, scientists need to document species' distribution and abundance as well as monitor how those numbers change over time. That's why Droege and several colleagues are working with the U.S. Forest Service to set up a nationwide bee-monitoring program. He recruited 11 experimental forest stations from places as far-flung as Maine, Colorado and Puerto Rico, and has created a standardized, almost foolproof collection strategy.