Beginning in October 2006, some beekeepers began reporting losses of 30-90
percent of their hives. While colony losses are not unexpected during winter
weather, the magnitude of loss suffered by some beekeepers was highly unusual.
This phenomenon, which currently does not have a recognizable underlying
cause, has been termed "Colony Collapse Disorder" (CCD). The main
symptom of CCD is simply no or a low number of adult honey bees present but
with a live queen and no dead honey bees in the hive. Often there is still
honey in the hive, and immature bees (brood) are present.
ARS scientists and others are in the process of carrying out research to
discover the cause(s) of CCD and develop ways for beekeepers to respond to the
problem.
Why should the public care about honey bees?
Bee pollination is responsible for $15 billion in
added crop value, particularly for specialty crops such as almonds and other
nuts, berries, fruits, and vegetables. About one mouthful in three in the diet
directly or indirectly benefits from honey bee pollination. While there are
native pollinators (honey bees came from the Old World with European
colonists), honey bees are more prolific and the easiest to manage for the
large scale pollination that U.S. agriculture requires. In California, the
almond crop alone uses 1.3 million colonies of bees, approximately one half of
all honey bees in the United States, and this need is projected to grow to 1.5
million colonies by 2010.
The number of managed honey bee colonies has dropped from 5 million in
the1940s to only 2.5 million today. At the same time, the call for hives to
supply pollination service has continued to climb. This means honey bee
colonies are trucked farther and more often than ever before.
Honey bee colony health has also been declining since the 1980s with the
advent of new pathogens and pests. The spread into the United States of varroa
and tracheal mites, in particular, created major new stresses on honey bees.
Is there currently a crisis in food production because of CCD?
While CCD has created a very serious problem for beekeepers and could
threaten the pollination industry if it becomes more widespread, fortunately
there were enough bees to supply all the needed pollination this past spring.
But we cannot wait to see if CCD becomes an agricultural crisis to do the
needed research into the cause and treatment for CCD.
The cost of hives for pollination has risen this year. But much of that is
due to growing demand. Some of the price increase may also be due to higher
cost of gas and diesel and other increases related to energy and labor costs.
Commercial beekeepers truck hives long distances to provide pollination
services, so in particular they must deal with rising expenses.
Varroa mites (one is visible on the back of this
bee) are a major threat to honey bee health and are becoming resistant to two
compounds (coumaphos and fluvalinate) used to control them. Beekeepers now have
a simple assay to determine whether mites are resistant and thus ensure use of
appropriate control measures. Click the image for more information about
it.
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Are there any theories about what may be causing CCD?
Case studies and questionnaires related to management practices and
environmental factors have identified a few common factors shared by those
beekeepers experiencing CCD, but no common environmental agents or chemicals
stand out as causative. There are three major possibilities that are being
looked into by researchers.
Pesticides may be having unexpected negative effects on honey bees.
A new parasite or pathogen may be attacking honey bees. One possible
candidate being looked at is a pathogenic gut microbe called Nosema. Viruses
are also suspected.
A perfect storm of existing stresses may have unexpectedly weakened colonies
leading to collapse. Stress, in general, compromises the immune system of bees
(and other social insects) and may disrupt their social system, making colonies
more susceptible to disease.
These stresses could include high levels of infection by the varroa mite (a
parasite that feeds on bee blood and transmits bee viruses); poor nutrition due
to apiary overcrowding, pollination of crops with low nutritional value, or
pollen or nectar scarcity; and exposure to limited or contaminated water
supplies. Migratory stress brought about by increased needs for pollination
might also be a contributing factor.
Has CCD ever happened before?
The scientific literature has several mentions of honey bee
disappearancesin the 1880s, the 1920s and the 1960s. While the
descriptions sound similar to CCD, there is no way to know for sure if the
problems were caused by the same agents as today's CCD.
There have also been unusual colony losses before. In 1903, in the Cache
Valley in Utah, 2000 colonies were lost to an unknown "disappearing
disease" after a "hard winter and a cold spring." More recently,
in 1995-96, Pennsylvania beekeepers lost 53 percent of their colonies without a
specific identifiable cause.
What about cell phonesdo they have anything to do with CCD?
The short answer is no.
There was a very small study done in Germany that looked at whether a
particular type of base station for cordless phones could affect honey bee
homing systems. But, despite all the attention that this study has received, it
has nothing to do with CCD. Stefan Kimmel, the researcher who conducted the
study and wrote the paper, recently e-mailed The Associated Press to say that
there is "no link between our tiny little study and the CCD-phenomenon ...
anything else said or written is a lie."
Newly emerged honey bee, Apis mellifera,
the subject of genome sequencing work aimed at improving bee traits and
management. Click the image for more information about it.
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What is ARS doing about CCD?
In April 2007, ARS held a Colony Collapse Disorder Research Workshop that
brought together over 80 of the major bee scientists, industry representatives,
extension agents, and others to discuss a research agenda. They identified
areas where more information is needed and the highest-priority needs for
additional research projects related to CCD.
A CCD Steering Committee, led by ARS and USDA's Cooperative State Research,
Education, and Extension Service, developed a Research Action Plan to
coordinate a comprehensive response for discovering what factors may be causing
CCD and what actions need to be taken.
One of the tools that will help in this research is the recently sequenced
honey bee genome to better understand bees' basic biology and breed better
bees, and to better diagnose bee pests and pathogens and their impacts on bee
health and colony collapse. The use of this genome information certainly will
have great applications in improving honey bee breeding and management.
The search for factors that are involved in CCD is focusing on four areas:
pathogens, parasites, environmental stresses, and bee management stresses such
as poor nutrition. It is unlikely that a single factor is the cause of CCD; it
is more likely that there is a complex of different components.
In September 2007, a research team that included ARS published the results
of an intensive genetic screening of CCD-affected honey bee colonies and
non-CCD-affected hives.
The only pathogen found in almost all samples from honey bee colonies with
CCD, but not in non-CCD colonies, was the Israeli acute paralysis virus (IAPV),
a dicistrovirus that can be transmitted by the varroa mite. It was found in
96.1 percent of the CCD-bee samples.
This research does not identify IAPV as the cause of CCD. What this research
found was strictly a strong correlation of the appearance of IAPV and CCD
together. No cause-and-effect connection can be inferred from the genetic
screening data. (More
information about this study)
Honey bees devour a new, nutrient-rich food
developed by ARS researchers. Click the image for more information about
it.
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This was the first report of IAPV in the United States. IAPV was initially
identified in honey bee colonies in Israel in 2002, where the honey bees
exhibited unusual behavior, such as twitching wings outside the hive and a loss
of worker bee populations.
The study also found IAPV in honey bees from Australia that had been
imported into the United States, as well as in royal jelly imported from China.
Australian bees began to be imported from Australia into the United States in
2005. Questions were raised about a connection between those imported bees and
the appearance of IAPV in the United States. Beekeepers sought out Australian
imports of bees as a way to replenish their hive populations.
To determine whether IAPV has been present in the United States since before
the importation of honey bees from Australia, a follow up detailed genetic
screening of several hundred honey bees that had been collected between 2002
and 2007 from colonies in Maryland, Pennsylvania, California and Israel was
conducted by ARS researchers.
The results of the follow study showed IAPV has been in this country since
at least 2002, which challenges the idea that IAPV is a recent introduction
from Australia. (More
information about this study)
This study in no way rules IAPV out as a factor in CCD. Research by several
groups will now focus on understanding differences in virulence across strains
of IAPV and on interactions with other stress factors. Even if IAPV proves to
be a cause of CCD, there still may also be other contributing factors-which
researchers are pursuing.
What should beekeepers do now about CCD?
Since little is known about the cause(s) of CCD right now, mitigation must
be based on improving general honey bee health and habitat and countering known
mortality factors by using best management practices.
What can I as a member of the public do to help honey bees?
The best action you can take to benefit honey bees is to not use pesticides
indiscriminately, especially not to use pesticides at mid-day when honey bees
are most likely to be out foraging for nectar.
In addition, you can plant and encourage the planting of good nectar sources
such as red clover, foxglove, bee balm, and joe-pye weed. For more information,
see www.nappc.org.]
ARS Honey Bee Research
More information about CCD can be found at:
Mid Atlantic Apiculture Research and Extension Consortium
http://maarec.cas.psu.edu/ColonyCollapseDisorder.html
Details of the Colony Collapse Disorder Action Plan are available in
PDF (portable document format) at:
http://www.ars.usda.gov/is/br/ccd/ccd_actionplan.pdf
For more information, contact:
Kim Kaplan, Agricultural Research Service, Information Staff, 301-504-1637;
Kim.Kaplan@ars.usda.gov.