More on the UCSF information
http://www.latimes.com/news/science/la-sci-bees26apr26,0,896792.story?coll=la-home-
headlines
Researchers link fungus to bee losses in U.S.
By Jia-Rui Chong and Thomas H. Maugh II
Times Staff Writers
5:06 PM PDT, April 25, 2007
A fungus that caused widespread loss of bee colonies in Europe and Asia may be playing a crucial
role in the mysterious phenomenon known as Colony Collapse Disorder that is now wiping out
bees across the U.S., University of California, San Francisco researchers said Wednesday.
Researchers have been struggling for months without success to explain the disorder, and the new
findings represent the first solid evidence pointing to a potential cause.
But the results are "highly preliminary" and are from only a few hives from Le Grand in California's
Merced County, UCSF biochemist Joe DeRisi said. "We don't want to give anybody the impression
that this thing has been solved."
Other researchers said Wednesday that they too had found the fungus, a single-celled parasite
called Nosema ceranae, in affected hives from around the country -- as well as in some hives that
have continued to survive and live. Those researchers also have found two other fungi and a half-
dozen viruses in the dead bees.
"N. ceranae" is "one of many pathogens" in the bees, said entomologist Diana Cox-Foster of
Pennsylvania State University. "By itself, it is probably not the culprit . . . but it may be one of the
key players."
Cox-Foster was one of the organizers of a meeting in Washington, D.C., on Monday and Tuesday
where about 60 bee researchers gathered to discuss Colony Collapse Disorder.
"We still haven't ruled out other factors, such as pesticides or inadequate food resources following
a drought," she said. "There are lots of stresses that these bees are experiencing," and it may be a
combination of factors that is responsible.
Historically, bee losses are not unusual. Weather, pesticide exposures and infestations by pests,
such as the Varroa mite, have wiped out significant numbers of colonies in the past, particularly in
the 1960s and 1970s.
But the current loss is unprecedented. Beekeepers in 28 states, Canada and England have reported
large losses. About a quarter of the estimated 2.4 million colonies across the United States have
been lost since last fall, said Jerry Hayes of the Florida Department of Agriculture and Consumer
Services in Gainesville.
"These are remarkable and dramatic losses," said Hayes, who is also president of the Apiary
Inspectors of America.
Besides a loss in honey production, commercial beehives are used to pollinate one-third of the
country's agricultural crops, including apples, peaches, pears, nectarines, cherries, strawberries
and pumpkins. Ninety percent of California's almond crop is dependent on bees, and a loss of
commercial hives could be devastating.
"For the most part, they just disappeared," said Florida beekeeper Dave Hackenberg, who was
among the first to note the losses. "The boxes were full of honey. That was the mysterious thing.
Usually other bees will rob those hives out. But nothing had happened."
Researchers now believe that the foraging bees are too weak to return to their hives.
DeRisi and UCSF's Don Ganem, who normally look for the causes of human diseases, were brought
into the bee search by virologist Evan W. Skowronski of the U.S. Army's Edgewood Chemical
Biological Center in Aberdeen, Md.
Dr. Charles Wick of the center had used a new system of genetic analysis to identify pathogens in
ground-up bee samples from California. He found several viruses, including members of a
recently identified family called iflaviruses.
It is not known if these small, RNA-containing viruses, which infect the Varroa mite, are
pathogenic to bees.
Skowronski forwarded the samples to DeRisi, who also found evidence of the viruses, along with
genetic material from Nosema.
"There was a lot of stuff from Nosema, about 25 percent of the total," Skowronski said. "That
meant there was more than there was bee RNA. That leads me to believe that the bee died from
that particular pathogen."
If Nosema does play a role in Colony Collapse Disorder, there may be some hope for beekeepers.
A closely related parasite called Nosema apis, which also affects bees, can be controlled by the
antibiotic fumagillin, and there is some evidence that it will work on N. ceranae as well.
FWIW I take Jerry Hayes to mean that the 25% figure of national losses includes winter losses too.
That would mean CCD losses is 10%-15% of the 2.4 million. I would still love to hear someone
clarify that number.
******************************************************
* Full guidelines for BEE-L posting are at: *
* http://www.honeybeeworld.com/bee-l/guidelines.htm *
******************************************************
|
