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UNDIAGNOSED DIE-OFF, APIS - USA: (MULTISTATE) (02)
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A ProMED-mail post
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International Society for Infectious Diseases
<http://www.isid.org>
Date: 26 Apr 2007
Source: Los Angeles Times [edited]
<http://www.latimes.com/news/la-sci-bees26apr26,0,7437491.story?track=mostviewed-storylevel>
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 wiping out bees across the United
States, UC San Francisco researchers said Wednesday [25 Apr 2007].
Researchers have been struggling for months to explain the disorder,
and the new findings provide the 1st solid evidence pointing to a
potential cause.
But the results are "highly preliminary" and are from only a few
hives from Le Grand in 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 [25 Apr 2007] that they too had
found the fungus, a single-celled parasite called Nosema ceranae
[This organism is actually a protozoan, please see note below - Mod.DHA], in affected hives from around the country, as well as in some hives
where bees had survived. Those researchers have also found 2 other
fungi and half a 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 [23-24 Apr 2007], 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 appears unprecedented. Beekeepers in 28 states,
Canada and Britain have reported large losses. About a quarter of the
estimated 2.4 million commercial colonies across the United States
have been lost since fall [2006], 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 producing honey, commercial beehives are used to pollinate
1/3rd of the country's agricultural crops, including apples, peaches,
pears, nectarines, cherries, strawberries and pumpkins. 90 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 1st 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 think 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 Maryland.
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 genus called Iflavirus.
It is not known whether 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 N. ceranae.
"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 N. ceranae 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 chemical Fumagillin, and there is some
evidence that it will work on N. ceranae as well.
[Byline: Jia-Rui Chong <jia-rui.chong@latimes.com> and Thomas H.
Maugh II <thomas.maugh@latimes.com>, Times Staff Writers]
--
Communicated by:
ProMED-mail Rapporteur Joseph P. Dudley, Ph.D
[Nosema is not a fungus as claimed in this report, but a
spore-forming protozoan. N. apis is widely known in Europe as a
pathogen of the honey bee Apis mellifera. N. ceranae was
originally discovered in the Asian bee A. cerana but was recently
also found in A. mellifera (see link below).
Iflavirus is a genus of invertebrate viruses only recently approved
by the International Committee on Taxonomy of Viruses.
Varroa mite (Varroa jacobsoni) is an ectoparasite of Apis spp.
and is widespread in the US, Europe and Asia. It has also been found
on some other flower-feeding insects which may serve as vectors.
Obviously, this is only a very 1st step towards solving the question
of the cause of the bee die-off. The likelihood of a multifactorial
disease is pointed out, and this will require extensive studies. In
the meantime, the loss of effective pollinators poses an economic
threat to horticultural industries such as, for example, stone fruit
production. However, there is no immediate threat of loss of trees.
Pictures: Nosema spores at
<http://www.ent.uga.edu/bees/images/nosema_spores.jpg>,
Varroa mite on bee larva at
<http://upload.wikimedia.org/wikipedia/en/c/c3/Varroa8536.JPG>.
Links:
Information on N. ceranae at
<http://www.moraybeekeepers.co.uk/nosema.htm>,
Information on nosemosis of honey bees at
<http://maarec.cas.psu.edu/bkCD/Bee_Diseases/Nosema.html>,
Description of the genus Iflavirus at
<http://www.ictvdb.rothamsted.ac.uk/ICTVdB/index.htm>,
Information on varroa mite at
<http://creatures.ifas.ufl.edu/misc/bees/varroa_mite.htm>,
Additional news stories at
<http://deseretnews.com/dn/view/0,1249,660214481,00.html> and
<http://news.bbc.co.uk/1/hi/england/somerset/6587069.stm>.
- Mod.DHA]
