For 23 years, beekeeper Tom Theobald has managed hundreds of bee colonies and tens of thousands bees in his apiaries as a labor of love. "There's something magical about being able to work with a natural system like this," he says of the uncommon craft of beekeeping.
But like the estimated 211,000 beekeepers around the United States, Mr. Theobald's Niwot Honey Farm has been hit in recent years by devastating losses of honeybees. Last winter, he lost 30 percent of his bees for the second year running - far above the typical winter die-off rate of 3 percent. "If you lose 30 percent of your livestock each year, it doesn't take long before ... you're down to zero," he says.
Although the decline of honeybees is a nationwide problem, in Colorado, it has become severe: While the state is home to only 1 percent of managed honeybee colonies in the country, one-fifth of all bee losses last year were reported here.
"There certainly is a very significant problem for winter mortality of bees. And clearly there are some problems here that are disproportionate to the rest of the country," says Frank Peairs, an entomologist at Colorado State University (CSU) who is conducting research on the losses.
Moreover, it isn't just the sweet, golden nectar produced by bees that's at stake. "The pollination provided by honeybees has a direct impact on agriculture to the tune of $10 billion a year, and another $10 billion indirectly. Bees are fundamental to about one-third of the US agricultural system, and one-third of the American diet," Theobald says.
Bees directly pollinate scores of fruit and vegetable crops, including apples, melons, strawberries, cherries, cucumbers, carrots, onions, and almonds. And the production of most beef and dairy products depend on the alfalfa and clover crops bees pollinate.
Honeybees - which were brought to America on the Mayflower by European settlers - have been on the decline domestically for several decades.
Following World War II, there were roughly 6 million honeybees in domestic managed colonies; today, there are fewer than half that number in the US.
But most of the losses have occurred in the past five years, prompting concerns that the industry is headed for collapse. "If something isn't done in the next few years, the industry is going to be completely destroyed," says Lyle Johnston, a Rocky Ford, Colo., beekeeper and president of the Colorado Beekeepers Association.
State officials and researchers have yet to establish the cause for the high die-off rate of honeybees, but they suggest a variety of factors are at play - including parasitic mites, bee disease, and the general use of pesticides.
Beekeepers, on the other hand, are focused on one agricultural pesticide in particular: microencapsulated methyl parathion - sold under the trade name Penncap-M.
A product of World War II nerve-gas research, Penncap-M is used primarily to control rootworm in corn (although it is also approved for use on apples, wheat, barley, cotton, and other crops).
The pesticide was used routinely in the 1970s, but was all but abandoned until the early 1990s, when a French chemical company began marketing it again to North American farmers. Since that time, honeybee mortality rates have risen tenfold.
Even though corn is pollinated by the wind, not bees, honeybees do have a taste for blooming cornflowers. And because Penncap-M is applied in small capsules about the size of pollen granules, bees may mistakenly take it back to their hive and store it for winter consumption, beekeepers believe. Come winter, according to their theory, bees tap into the supply, and die off in droves.
"Penncap is like a bait for the bees, and once it's in the hive, it's like a time bomb waiting to explode," says Mr. Johnston, who is the state's largest commercial honey producer with some 4,000 honeybee colonies. "This pesticide is devastating to bees."
A number of states, including California and Washington State have identified the pesticide as a culprit in their bee-kills, and now allow only limited use of Penncap-M. And their die-off rates have since been reduced.
Colorado policymakers acknowledge that Penncap-M caused the bee deaths in other states, and that those states have the research to back it up. But they are not willing to say the same thing is happening here until there is proof, they say.
"There has been a lot of speculation, but we're waiting for the scientific research," says Janet Jackson, spokeswoman for the Colorado Department of Agriculture.
"The beekeepers have made up their minds that Penncap-M is the culprit," she continues. "That certainly is a possibility. However, with the number of bees we've seen dying in the last few years, I'm not sure that all those bees were feeding on crops treated with it."
A combination of factors is more likely, she says, pointing to two types of parasitic mites that have appeared in the US in the past decade, and have wreaked havoc on some colonies. Also, a bee disease called foulbrood may play a role. And other insecticides haven't been ruled out.
For now, the state awaits decisive evidence from CSU researcher Dr. Peairs. "We're about a year away from being able to say anything conclusive," reports Peairs, whose two-year study is funded by the state Department of Agriculture.
As for the role of Penncap-M, Peairs notes that while the pesticide is known to be hazardous to bees, "the question is whether it's a problem in our state. We don't know that."
Yet as beekeepers prepare to assess this winter's losses, they have little patience for the state's wait-and-see approach. "This should be of concern to the people making policy," says Theobald. "Ultimately, it's a question that revolves around the food security of this country."
TO Johnson, a third-generation beekeeper, the Department of Agriculture's position is no surprise, he says, considering the political and financial clout of the chemical and agricultural industries - and the relative obscurity of beekeepers.
"The state is doing everything to make it out as a beekeeping problem instead of a pesticide problem. They're calling it mites because they don't want to have to do anything about it."
In fact, mites have been around for a decade, and commercial beekeepers use management techniques - including menthol chips and oils - to keep them away, he says. "We've learned to deal with mites. But pesticides we can't control."
He tells the story of one beekeeper who called state agriculture officials to his property after he discovered colony after colony of dead honeybees. "It was obviously from a pesticide. But the first thing the state official said to the beekeeper was, 'Are you sure it wasn't mites?' That's like saying to a farmer after his crop has been destroyed by a hailstorm, 'Are you sure it wasn't a UFO?' " says Johnston.