Scientists have found a new prime suspect in the deaths of about a quarter of America's honeybees, a mystery that could take a multibillion-dollar toll on the nation's agricultural industry.
Months of genetic testing have fingered a virus that was first reported in Israel just three years ago and may have passed through Australia on its way to the United States. The correlation between Israeli Acute Paralysis Virus and the mysterious bee disease — known as Colony Collapse Disorder, or CCD — was reported Thursday on the journal Science's Web site.
Although the scientists behind the research cautioned that they haven't yet cracked the case, their study provides enough curious coincidences to keep even the fictional detective (and beekeeper) Sherlock Holmes buzzing.
The economic effect of the bee disappearances goes far beyond the lost honey: In fact, the bee industry's primary impact is felt through the crops that the insects pollinate — products that are valued at $14 billion to $20 billion annually. Since Colony Collapse Disorder first came to light last year, the malady has affected an estimated 23 percent of the nation’s beekeeping operations, with losses of up to 90 percent. Other countries are reporting mysterious bee losses as well.
The disorder is characterized by the rapid disappearance of a colony's bees, even if there are adequate stores of food in the hive. The bees just seem to fly off into oblivion — hinting that the malady somehow affects the insects’ navigational sense or learning ability.
The latest research moves Israeli Acute Paralysis Virus to the top of the list as a "significant marker" for Colony Collapse Disorder, the researchers reported. And they said the technique they used could be applied to other disease outbreaks as well, even those that afflict humans.
The genetic game’s afoot
The scientific sleuths began their investigation early this year by sampling bees from four colonies that suffered a collapse, and two healthy colonies. They also took samples from apparently healthy bees imported from Australia and royal jelly from China. Royal jelly is a special food secreted by bees that is also used in cosmetics.
Those samples were run through gene-sequencing machines and meticulously analyzed. The researchers subtracted out the honeybee genome itself, then identified the genetic markers of bacteria, fungi and viruses that were left over. A similar technique was recently used to identify 182 species of bacteria living on human skin.
Penn State's Edward Holmes concentrated on an in-depth analysis of viruses found in the bee samples. "This is breaking new ground in trying to look at how viruses work in this class of animals," he told reporters Wednesday during a pre-publication teleconference.
"We found a remarkably high viral burden in bee populations. ... We characterize in this paper seven different viruses that circulate in bee populations. Only one of them was consistently associated with CCD and royal jelly," he said.
That was Israeli Acute Paralysis Virus, or IAPV — a little-known bug that sets bees' wings shivering and eventually causes paralysis. IAPV-afflicted bees are typically found dead outside their hives. IAPV was also detected in the Australian bees as well as two of the four Chinese royal jelly samples.
These initial clues led the researchers to look for IAPV and other suspected pathogens in more bee samples. They checked the genetic sequences for bees collected over the past three years from 30 colonies that suffered a collapse and 21 healthy colonies. The presence of IAPV was found to be the best indicator for Colony Collapse Disorder, with a 96.1 percent correlation.
Not so elementary
"I hope no one goes away with the idea that we've actually solved the problem," Jeff Pettis of the U.S. Department of Agriculture's Agricultural Research Service told reporters. "We still have a great deal of research to do to resolve why bees are dying in the U.S. and elsewhere."
Among the questions yet to be answered:
- Is IAPV really a cause, or will it turn out that vulnerability to the virus is merely a consequence of the disease?
- How and when did IAPV get into the United States?
- Why did the Australian bees (and even a few American bees) seem healthy even though they were carriers of the virus?
- What roles are played by other bugs that were found in the bee samples, such as the Kashmir bee virus and Nosema fungi?
- If the cause or causes can be definitively identified, what can be done to stop the collapse?
The first task ahead is to confirm the linkage with the virus and figure out the actual mechanism behind Colony Collapse Disorder. Not everyone is convinced IAPV will turn out to be the culprit. Researchers from the U.S. Army and Montana-based Bee Alert Technology have turned up IAPV and other viruses in sick and healthy bees — but have not found any pattern of correlation.
"For the good of the industry, we wish they had a smoking gun and a quick answer, but we're not convinced they're there," Bee Alert's Jerry Bromenshenk told msnbc.com. He said he and his colleagues have turned up more than a dozen suspect viruses, including "a bunch we're still scratching our heads over."
Scientists suspect that some sort of organism will turn out to be the leading cause of the bee collapse, whether it's IAPV, a different virus or a combination of bugs. That's because irradiating beehives appears to make them safe for recolonization, Pettis said.
The Australian connection is another line of investigation: The United States allowed the import of packaged Australian bees in 2004, and reports of bee disappearances began soon afterward, Pettis noted. That may be how IAPV came into the country, though Pettis said it's also possible the virus was here before that time.
Colin Henderson, one of Bromenshenk's colleagues at Bee Alert, said it was still premature to assume that the virus was passed from Australia to America. Pettis said tests of bee samples that were taken in the United States and frozen before 2004 could shed light on whether there's a connection or not.
If Australian bees are carrying the virus, why aren't bee colonies collapsing Down Under? Pettis noted that the Australian bees aren't afflicted by Varroa mites, which have decimated America's wild bee population in recent years. As a result, the Australians may have weathered the stress of IAPV better than their American cousins. "That alone could account for the differences between the two countries," he said.
In the weeks ahead, the researchers behind the Science study will try combining IAPV with other stress factors to see if they can experimentally create the conditions that tip a healthy bee colony into a collapse.
Is there a 100 percent solution?
Pettis said it's still too early to propose putting new restrictions on bee imports. "We're looking at the science behind it and what we feel needs to be done, but no decisions have been made at this time," he said.
Just to be safe, beekeepers should refrain from using imported royal jelly in their hives, he said.
Pettis said Colony Collapse Disorder was almost certainly the result of a "combination of things," and he didn't expect a magic antiviral bullet to appear anytime soon. "We're really right now going to have to rely on beekeepers to continue just to manage nutrition, parasitic mites, Nosema, things like that — and try to keep bees as healthy as possible," Pettis told msnbc.com.
There's more hope on the horizon: Recent research in Israel indicates that some bees have become resistant to IAPV by incorporating the virus' genetic code into their own genes. Creating virus-resistant strains of bees, either through genetic modification or old-fashioned breeding, "is a very intriguing idea," Pettis said.
At the same time, the strategy used to track down the genetic correlation between Colony Collapse Disorder and the suspect virus provides a "road map for rigorously and efficiently addressing outbreaks of infectious disease," said W. Ian Lipkin, a molecular biologist at Columbia University's Mailman School of Public Health who was the corresponding author for the Science study.
"I really do think that these new technologies will revolutionize our approach to epidemiology and the characterizing of outbreaks of infectious disease," he said.
If the strategy were available in 2003, public-health experts might have been able to track down the roots of severe acute respiratory syndrome, or SARS, in much less time than the months that were required back then, Lipkin said.
"We would be able to get similar sorts of answers in as short as a week," he said.
In addition to Cox-Foster, Lipkin, Holmes and Pettis, the researchers behind the Science study included Sean Conlan, Gustavo Palacios, Phenix-Lan Quan, Thomas Briese, Mady Hornig, Andrew Drysdale, Jeffrey Hui and Junhui Zhai of Columbia University; Jay Evans of the USDA-ARS Bee Research Laboratory; Nancy Moran and Vince Martinson of the University of Arizona; David Geiser, Dennis vanEngelsdorp, Abby Kalkstein and Liwang Cui of Penn State; and Stephen Hutchison, Jan Fredrik Simons and Michael Egholm of 454 Life Sciences.
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