Buzz kill

Pub date January 27, 2010
WriterSarah Phelan
SectionGreen City

GREEN CITY Everyone loves a juicy red tomato. But who knew that the burgeoning hothouse tomato industry, which now accounts for 17 percent of the U.S. fresh tomato supply, imports millions of loudly buzzing commercially reared bumble bees to pollinate its crops? And that pathogen spillover from Bombus impatiens, a bumblebee reared commercially on the East Coast, could be decimating wild bee populations in California and Oregon?

These concerns are outlined in a petition filed with the U. S. Department of Agriculture’s Animal and Plant Health Inspection Service to regulate the movement of commercially reared bumblebees.

“Bumblebees are excellent crop pollinators and serve as an insurance policy for farmers when honeybees are in short supply,” the Jan. 12 petition states. It’s signed by Robbin Thorp, professor emeritus of UC Davis’ entomology department, the Xerces Society for Invertebrate Conservation, Defenders of Wildlife, and the Natural Resources Defense Council.

Recent research by Thorp and Xerces established that four species of formerly common North American feral bumblebees have experienced steep declines and two species are teetering on the brink of extinction.

“The most dramatic decline in North American bumblebees is most likely caused by introduced disease from commercial bee-rearing and movement,” the petitioners state. They believe commercial bees spread pathogens by escaping into the wild where they forage for nectar on flowers visited by feral bees. And they want APHIS to prohibit the movement of bumblebees outside their native range, which the petitioners define as “the state line closest to the side of the 100th meridian,” which runs, roughly, from Texas to North Dakota.

USDA’s Larry Hawkins said APHIS is examining petitioners’ claims. “We need to evaluate whether there is a need, whether it’s practical, and whether the pest is so widely distributed to make that infeasible,” Hawkins said.

James Strange, a USDA-APHIS researcher, acknowledged that “a couple of scientists from Canada put out pretty convincing papers suggesting that something is happening to wild bumblebees that live in the close vicinity of commercial greenhouse operations that use commercial bumblebees to buzz-pollinate their crops.”

But he doesn’t believe Thorp and the Xerces Society have convincing proof that what’s happening to feral bumblebees in California and Oregon is related to commercially reared escape artists.

“They are basing their conclusions on anecdotal stuff,” Strange said. “The idea that the greenhouse tomato growers use of commercially reared bumblebees is what’s causing population declines in the wild is not a good connection because we found the pathogen in natural forests, too.”

Strange noted that the Xerces Society’s petition could be disastrous for some agricultural sectors, if such a rule became hard and fast tomorrow. “But if it’s phased in over the next five years, it could give the industry time to find an alternative,” he said.

Bumblebees are more effective pollinators than honeybees for plants like hybrid sunflowers, watermelon, squash, tomatoes, raspberries, blueberries, cranberries, and peppers. Their thick, tundra-adapted fur helps them survive cold, foggy conditions and their loud buzz, which sounds like someone blowing a raspberry, helps them pollinate plants like tomatoes by shaking pollen out of the flowers’ anthers and onto their velvety pelts.

But bumblebees don’t form permanent colonies, and hothouse tomato growers were forced to pollinate crops with handheld electric vibrators until R. De Jonghe, a Belgian veterinarian, figured how to trick pregnant queens into laying eggs year-round.

Today the four major U.S. hothouse tomato growers use commercially reared bumblebees to pollinate crops. A single greenhouse can be as large as 20 acres and contain 200,000 plants and 23,000 commercially reared bees. According to a hothouse tomato industry report, growers spend up to $2,000 per acre on importing bumblebees. In 2001, 309 million pounds of hothouse tomatoes were grown on 718 acres nationwide.

Strange is trying to find ways to raise local species of bumblebees in captivity so agriculture can use locals instead of the East Coast imports, a technique that involves tricking pregnant bumblebee queens into ending their winter hibernation early.

So far, he has managed to trick one West Coast species into nesting this way. “So it seems like it is possible,” Strange said.