Israeli Virus Linked to Devastating Bee Disease
UNIVERSITY PARK, Pennsylvania, September 7, 2007 (ENS) - Scientists are homing in on a possible cause of the new bee disease known as colony collapse disorder, linking it with a virus from Israel that may have arrived in the United States via shipments of live bees from Australia.
Since it was first reported in 2004, colony collapse disorder, CCD, has affected 23 percent of the commercial bee colonies in the United States, causing losses of from 50 to 90 percent of the bees in each colony.
Honeybee on a peach blossom. Bees are essential for pollination of 90 fruit and vegetable crops worldwide. (Photo by Z. Huang courtesy Michigan State University)
A team of entomologists and infectious disease researchers are reporting a "strong correlation" between the colony collapse disorder and a virus, the Israeli Acute Paralysis Virus, IVAP, identified just three years ago.
This is the first report of IAPV in the United States, the scientists said, adding that this virus is transmitted by the varroa mite, found in many U.S. hives.
But the scientists are serving up the results of their study with a dose of caution.
"We have not proven a causal relationship between any infectious agent and CCD," they wrote in Thursday's issue of "Science Express" online.
They did find that the prevalence of IAPV genetic material in bees suffering from colony collapse disorder, the timing of the outbreaks and the geographical circumstances "indicate that IAPV is a significant marker for CCD."
On the hunt for the cause of colony collapse disorder, the researchers decided to sequence the genetic material in bees to try to find a potential pathogen.
"The genome of the honey bee had just been completed," said principal researcher Diana Cox-Foster, professor of entomology at Penn State. "So it was possible to do the sequencing and then eliminate the genetic material of the bees."
Entomologist Diana Cox-Foster in her laboratory (Photo by Jill Shockey courtesy Penn State)
To prepare their samples for analysis, the scientists froze and pulverized bees from infected hives and compared their genetic material with that of bees that were not diseased.
The samples sequenced included bees from four geographically separated CCD suffering operations, apparently healthy bees imported from Australia, non-diseased samples from Pennsylvania and Hawaii, and samples of royal jelly imported from China. Royal jelly is secreted by bees and used to feed all larvae, but those fed only with royal jelly become queens.
"We chose bees from Hawaii because at that time, those populations were free of varroa mites, a problem in all mainland hives," says Cox-Foster. "The royal jelly was not intended for bees, but for human consumption and cosmetics, but some beekeepers use it to create new queens." Some hives in Hawaii have since become infected with varroa mites.
The researchers grouped material for sequencing as presumed CCD positive, presumed CCD negative and royal jelly. The genetic material was analyzed for bacteria, fungi, parasites and viruses matches.
The team studying the role of infection in colony collapse disorder includes Ian Lipkin, director of the Center for Infection and Immunity at Columbia University Mailman School of Public Health, Jeffery Pettis, research leader of the U.S. Department of Agriculture's Bee Research Laboratory, and Nancy Moran, professor at the University of Arizona-Tucson.
Dr. Lipkin said, "The profound synergy within the group - bringing entomology, microbiology, and bioinformatics together - enabled us to work toward a solution to this extraordinarily complex problem."
Dr. Ian Lipkin (Photo courtesy The Ellison Medical Foundation)
Using the high-throughput DNA sequencing platform developed by 454 Life Sciences Corportion of Branford, Connecticut, and analytical methods developed at Columbia, Dr. Lipkin’s team searched for footprints of viruses, bacteria, fungi, and parasites in thousands of sequences.
The genetic sequences were matched against GenBank, a database of genetic sequences maintained by the U.S. National Center for Biology Information. Ninety-six percent of the genetic material matched that already has been found in bees.
When Cox-Foster's and Lipkin's groups analyzed the viruses, they found the expected viruses, and they found one that, while identified by researchers at Hebrew University in 2004, has just now appeared in scientific publication.
This virus, the Israeli Acute Paralysis Virus, along with another, the Kashmir bee virus, KBV, was found only in bee populations with colony collapse disorder.
"IAPV was found in all four affected operations sampled, in two of four royal jelly samples and in the Australian sample," the researchers wrote. "KBV was present in three of four CCD operations, but not in the royal jelly."
IAPV was found to increase the risk of colony collapse disorder, but Kashmir bee virus did not, the scientists report.
Healthy bees in their hive. (Photo courtesy USDA)
In a news conference Thursday, the scientists said that their findings do not definitively identify the IAPV virus as the cause of colony collapse disorder.
"I hope no one goes away with the idea that we’ve actually solved the problem," said Pettis. "We still have a great deal of research to do to resolve why bees are dying."
"The next step is to determine whether IAPV, alone or in concert with other factors, can induce CCD in healthy bees," said Dr. Lipkin.
Timing may be the key to pinpointing the cause, the scientists say.
The United States began allowing importation of bees from Australia in 2004, when early reports of colony collapse disorder began. The same year, IAPV was described by Israeli researchers with symptoms of shivering wings, progressed paralysis and bees dying outside the hive.
Colony collapse disorder does not seem to have the same symptoms, and IAPV also was found in non-CCD hives in some cases.
The researchers said these results could reflect strain variation, co-infection, or the presence of other stressors, such as pesticides or poor nutrition.
The brown bumps on these bees are varroa mites. (Photo by Lila De Guzman courtesy USDA)
The varroa mite, for example, which is absent in Australia, immunosuppresses bees making them more susceptible to infection by other organisms, including viruses. Other stressors may include chemical pesticides used on plants pollinated by bees and in hives to control pests.
Australian Honeybee Industry Association spokesman Stephen Ware says the report has unfairly jeopardized Australia's $5 million live bee export market. Live bees are a fast-growing export commodity from Australia to the United States, as beekeepers attempt to repopulate hives emptied by colony collapse disorder.
Australian beekeepers sent more than 30,000 packages of bees to the United States last summer, but the U.S. Department of Agriculture is now considering a ban on imports.
"We believe that it's un-scientific. The jury is still out on what causes colony collapse disorder or for that matter, whether there is such a thing as colony collapse disorder," Ware told the Australian Broadcasting Corporation today.
"We're concerned that this report in the United States may be used by some as an excuse to prevent exports from Australia to the United States."
Tasmanian Beekeepers Association spokesman Julian Wolfhagen says U.S. commercial interests are behind the claim.
"I can't see any plausible reason why - particularly as Australia is comparatively disease-free, particularly when compared to the United States - we could have some malaise that we're not aware of," he said.
"We don't have any CCD symptoms here in Australia," said Wolfhagen. Why should it then pop up with our bees in the USA? Not likely."
Colony Collapse Disorder is affecting bees in more than 22 states, according to the U.S. Department of Agriculture, threatening the production of crops dependent on bees for pollination as well as honey production.
Bees play an integral role in the world food supply, and are essential for the pollination of over 90 fruit and vegetable crops worldwide, particularly for specialty crops such as nuts, berries, fruits, and vegetables. These agricultural products are worth more than $14.6 billion annually in the United States alone.
Copyright Environment News Service (ENS) 2007. All rights reserved.
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