April 24, 2007
Bees Vanish, and Scientists Race for Reasons
Joe Raedle/Getty Images
MYSTERY Honeybee colonies around the nation are
collapsing. Above, a beekeeper in Loxahatchee, Fla.
BELTSVILLE, Md., April 23 — What is happening to the bees?
More than a quarter of the country's 2.4 million
bee colonies have been lost — tens of billions of
bees, according to an estimate from the Apiary
Inspectors of America, a national group that
tracks beekeeping. So far, no one can say what is
causing the bees to become disoriented and fail to return to their hives.
As with any great mystery, a number of theories
have been posed, and many seem to researchers to
be more science fiction than science. People have
blamed genetically modified crops, cellular phone
towers and high-voltage transmission lines for
the disappearances. Or was it a secret plot by
bin Laden to bring down American agriculture? Or,
as some blogs have asserted, the rapture of the
bees, in which God recalled them to heaven? Researchers have heard it all.
The volume of theories "is totally
mind-boggling," said Diana Cox-Foster, an
State University. With Jeffrey S. Pettis, an
entomologist from the
States Department of Agriculture, Dr. Cox-Foster
is leading a team of researchers who are trying
to find answers to explain "colony collapse
disorder," the name given for the disappearing bee syndrome.
"Clearly there is an urgency to solve this," Dr.
Cox-Foster said. "We are trying to move as quickly as we can."
Dr. Cox-Foster and fellow scientists who are here
at a two-day meeting to discuss early findings
and future plans with government officials have
been focusing on the most likely suspects: a virus, a fungus or a pesticide.
About 60 researchers from North America sifted
the possibilities at the meeting today. Some
expressed concern about the speed at which adult
bees are disappearing from their hives; some
colonies have collapsed in as little as two days.
Others noted that countries in Europe, as well as
Guatemala and parts of Brazil, are also struggling for answers.
"There are losses around the world that may or
not be linked," Dr. Pettis said.
The investigation is now entering a critical
phase. The researchers have collected samples in
several states and have begun doing bee autopsies and genetic analysis.
So far, known enemies of the bee world, like the
varroa mite, on their own at least, do not appear
to be responsible for the unusually high losses.
Genetic testing at
University has revealed the presence of multiple
micro-organisms in bees from hives or colonies
that are in decline, suggesting that something is
weakening their immune system. The researchers
have found some fungi in the affected bees that
are found in humans whose immune systems have
been suppressed by the Acquired Immune Deficiency
"That is extremely unusual," Dr. Cox-Foster said.
Meanwhile, samples were sent to an Agriculture
Department laboratory in North Carolina this
month to screen for 117 chemicals. Particular
suspicion falls on a pesticide that France banned
out of concern that it may have been decimating
bee colonies. Concern has also mounted among public officials.
"There are so many of our crops that require
pollinators," said Representative Dennis Cardoza,
a California Democrat whose district includes
that state's central agricultural valley, and who
presided last month at a Congressional hearing on
the bee issue. "We need an urgent call to arms to
try to ascertain what is really going on here
with the bees, and bring as much science as we
possibly can to bear on the problem."
So far, colony collapse disorder has been found
in 27 states, according to Bee Alert Technology
Inc., a company monitoring the problem. A recent
survey of 13 states by the Apiary Inspectors of
America showed that 26 percent of beekeepers had
lost half of their bee colonies between September and March.
Honeybees are arguably the insects that are most
important to the human food chain. They are the
principal pollinators of hundreds of fruits,
vegetables, flowers and nuts. The number of bee
colonies has been declining since the 1940s, even
as the crops that rely on them, such as
California almonds, have grown. In October, at
about the time that beekeepers were experiencing
huge bee losses, a study by the
Academy of Sciences questioned whether American
agriculture was relying too heavily on one type of pollinator, the honeybee.
Bee colonies have been under stress in recent
years as more beekeepers have resorted to
crisscrossing the country with 18-wheel trucks
full of bees in search of pollination work. These
bees may suffer from a
that includes artificial supplements, concoctions
akin to energy drinks and power bars. In several
states, suburban sprawl has limited the bees' natural forage areas.
So far, the researchers have discounted the
possibility that poor diet alone could be
responsible for the widespread losses. They have
also set aside for now the possibility that the
cause could be bees feeding from a commonly used
genetically modified crop, Bt corn, because the
symptoms typically associated with toxins, such
as blood poisoning, are not showing up in the
affected bees. But researchers emphasized today
that feeding supplements produced from
genetically modified crops, such as high-fructose
corn syrup, need to be studied.
The scientists say that definitive answers for
the colony collapses could be months away. But
recent advances in biology and genetic sequencing are speeding the search.
Computers can decipher information from
and match pieces of genetic code with particular
organisms. Luckily, a project to sequence some
11,000 genes of the honeybee was completed late
last year at
University, giving scientists a huge head start
on identifying any unknown pathogens in the bee tissue.
"Otherwise, we would be looking for the needle in
the haystack," Dr. Cox-Foster said.
Large bee losses are not unheard of. They have
been reported at several points in the past
century. But researchers think they are dealing
with something new — or at least with something previously unidentified.
"There could be a number of factors that are
weakening the bees or speeding up things that
shorten their lives," said Dr. W. Steve Sheppard,
a professor of entomology at
State University. "The answer may already be with us."
Scientists first learned of the bee
disappearances in November, when David
Hackenberg, a Pennsylvania beekeeper, told Dr.
Cox-Foster that more than 50 percent of his bee
colonies had collapsed in Florida, where he had taken them for the winter.
Dr. Cox-Foster, a 20-year veteran of studying
bees, soon teamed with Dennis vanEngelsdorp, the
Pennsylvania apiary inspector, to look into the losses.
In December, she approached W. Ian Lipkin,
director of the Greene Infectious Disease
Laboratory at Columbia University, about doing
genetic sequencing of tissue from bees in the
colonies that experienced losses. The laboratory
uses a recently developed technique for reading
and amplifying short sequences of DNA that has
revolutionized the science. Dr. Lipkin, who
typically works on human diseases, agreed to do
the analysis, despite not knowing who would
ultimately pay for it. His laboratory is known
for its work in finding the
Nile disease in the United States.
Dr. Cox-Foster ultimately sent samples of bee
tissue to researchers at Columbia, to the
Agriculture Department laboratory in Maryland,
and to Gene Robinson, an entomologist at the
of Illinois. Fortuitously, she had frozen bee
samples from healthy colonies dating to 2004 to use for comparison.
After receiving the first bee samples from Dr.
Cox-Foster on March 6, Dr. Lipkin's team
amplified the genetic material and started
sequencing to separate virus, fungus and parasite DNA from bee DNA.
"This is like C.S.I. for agriculture," Dr. Lipkin
said. "It is painstaking, gumshoe detective work."
Dr. Lipkin sent his first set of results to Dr.
Cox-Foster, showing that several unknown
micro-organisms were present in the bees from
collapsing colonies. Meanwhile, Mr. vanEngelsdorp
and researchers at the Agriculture Department lab
here began an autopsy of bees from collapsing
colonies in California, Florida, Georgia and
Pennsylvania to search for any known bee pathogens.
At the University of Illinois, using knowledge
gained from the sequencing of the bee genome, Dr.
Robinson's team will try to find which genes in
the collapsing colonies are particularly active,
perhaps indicating stress from exposure to a toxin or pathogen.
The national research team also quietly began a
parallel study in January, financed in part by
the National Honey Board, to further determine if
something pathogenic could be causing colonies to collapse.
Mr. Hackenberg, the beekeeper, agreed to take his
empty bee boxes and other equipment to Food
Technology Service, a company in Mulberry, Fla.,
that uses gamma rays to kill bacteria on medical
equipment and some fruits. In early results, the
irradiated bee boxes seem to have shown a return
to health for colonies repopulated with Australian bees.
"This supports the idea that there is a pathogen
there," Dr. Cox-Foster said. "It would be hard to
explain the irradiation getting rid of a chemical."
Still, some environmental substances remain suspicious.
Chris Mullin, a Pennsylvania State University
professor and insect toxicologist, recently sent
a set of samples to a federal laboratory in
Raleigh, N.C., that will screen for 117
chemicals. Of greatest interest are the
"systemic" chemicals that are able to pass
through a plant's circulatory system and move to
the new leaves or the flowers, where they would come in contact with bees.
One such group of compounds is called
neonicotinoids, commonly used pesticides that are
used to treat corn and other seeds against pests.
One of the neonicotinoids, imidacloprid, is
commonly used in Europe and the United States to
treat seeds, to protect residential foundations
against termites and to help keep golf courses and home lawns green.
In the late 1990s, French beekeepers reported
large losses of their bees and complained about
the use of imidacloprid, sold under the brand
name Gaucho. The chemical, while not killing the
bees outright, was causing them to be disoriented
and stay away from their hives, leading them to
die of exposure to the cold, French researchers
later found. The beekeepers labeled the syndrome "mad bee disease."
The French government banned the pesticide in
1999 for use on sunflowers, and later for corn,
despite protests by the German chemical giant
Bayer, which has said its internal research
showed the pesticide was not toxic to bees.
Subsequent studies by independent French
researchers have disagreed with Bayer. Alison
Chalmers, an eco-toxicologist for Bayer
CropScience, said at the meeting today that bee
colonies had not recovered in France as
beekeepers had expected. "These chemicals are not
being used anymore," she said of imidacloprid,
"so they certainly were not the only cause."
Among the pesticides being tested in the American
bee investigation, the neonicotinoids group "is
the number-one suspect," Dr. Mullin said. He
hoped results of the toxicology screening will be ready within a month.