Honey bees (Apis mellifera)
are the most economically valuable pollinators of agricultural crops
worldwide and are the only bee species kept commercially in the United
States. In the United States, bee pollination of agricultural crops is
said to account for about one-third of the U.S. diet, and to contribute to
the production of a wide range of high-value fruits, vegetables, tree
nuts, forage crops, some field crops, and other specialty crops.
Over the past number of
years, massive amounts of bees have been dying from parasites, viruses and
a whole host of other ailments. But, the most impactfull has been from an
unexplained syndrome known only as colony collapse disorder (or CCD),
where the bees simply disappear from their hives and never return.
Honey bee populations have
been mysteriously falling for at least five years in the United States,
but the cause of so-called colony collapse disorder (CCD) is still largely
areas show reported affected states
observed similar phenomena in Belgium, France, the Netherlands, Greece,
Italy, Portugal, and Spain and initial reports have also come in from
Switzerland and Germany.
In the fall of 2006, a
loud, new buzz began among beekeepers in a number of countries when
managed honey bee colonies began to disappear in large numbers without
known reason. By February 2007, the syndrome, which is characterized by
the disappearance of all adult honey bees in a hive while immature bees
and honey remain, had been christened “colony collapse disorder” (CCD).
Some beekeepers reported
losses of 30-90 percent of their hives during the 2006 winter. While
colony losses are not unexpected during winter weather, the magnitude of
loss suffered by these beekeepers was highly unusual.
Because honey bees are
critical for agricultural pollination—adding more than $15 billion in
value to about 130 crops—especially high-value specialty crops like
berries, nuts, fruits, and vegetables, the unexplained disappearance of so
many managed colonies was not a matter to take lightly.
In general, honey bee
colony health has been declining since the 1980s, with the introduction 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. At the same time, the call for hives to supply pollination services
has continued to climb. This means honey bee colonies are trucked farther
and more often than ever before, which also stresses the bees.
There have been many
theories about the cause of CCD, but the researchers who are leading the
effort to find out why are now focused on these factors:
increased losses due to
the invasive varroa mite (a pest of honeybees);
new or emerging diseases
such as Israeli Acute Paralysis virus and the gut parasite Nosema;
through exposure to pesticides applied to crops or for in-hive insect
or mite control;
bee management stress;
immune-suppressing stress on bees caused by one or a combination of
factors identified above.
Additional factors may
include poor nutrition, drought, and migratory stress brought about by the
increased need to move bee colonies long distances to provide pollination
disappearance of bees, called Colony Collapse Disorder (CCD), is a growing
threat to honey bees, the mainstay of pollination services in agriculture.
CCD appears to
be occurring across the United States. CCD is an infectious disease affecting
managed European honey bees (Apis mellifera) in commercial beekeeping operations
across the United States. CCD has resulted in losses of 50 to 90% of managed
colonies in U.S. beekeeping operations during the past several years.
malady was first reported in the media during the fall months of 2006, but may
have been noticed by beekeepers as early as 2004, about the time when USDA-APHIS
regulations were relaxed to allow for the importation of package bee colonies
and queens from Australia and other countries, due to a shortage of colonies to
pollinate the burgeoning California almond crop.
| Silence of the Bees | Inside the Hive | PBS
CCD Differs from Past Bee Colony Losses
bee colony losses seem to differ from past losses in that colony
losses are occurring mostly because bees are failing to return to the
hive (which is largely uncharacteristic of bee behavior); bee colony
losses have been rapid; colony losses are occurring in large numbers;
and the reason why these losses are occurring remains still largely
phenomenon was first called “Fall-Dwindle Disease,” but was
renamed because of the unusual characteristics of the colony declines.
Moreover, the condition is not only seasonal but manifests itself
throughout the year. The term “dwindle” implies a gradual loss,
whereas CCD onset is sudden. Also, the term “disappearance” is
used to describe other types of conditions, which differ from the
symptoms currently being associated with CCD. Finally, the term “disease”
is usually associated with a biological agent, but none has yet been
Among the key
symptoms of CCD in collapsed colonies is that the adult population is
suddenly gone without any accumulation of dead bees. The bees are not
returning to the hive but are leaving behind their brood (young bees),
their queen, and maybe a small cluster of adults. What is uncharacteristic
about this situation is that the honey bee is a very social insect and
colonyoriented, with a complex and organized nesting colony. Failing to
return to the hive is considered highly unusual. An absence of a large
number of dead bees makes an analysis of the causes of CCD difficult. Also
there is little evidence that the hive may have been attacked. In actively
collapsing colonies, an insufficient number of adult bees remain to care
for the brood. The remaining workforce seems to be made up of young adult
bees. The queen is present, appears healthy and is usually still laying
eggs, but the remaining cluster is reluctant to consume feed provided by
the beekeeper, and foraging is greatly reduced.
Questions and Answers:
Colony Collapse Disorder From The USDA
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.
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.
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
The scientific literature
has several mentions of honey bee disappearances—in 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
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.
Credit: Texas A&M University, National
Honey Board , Penn State, PBS, USDA
compiled from The British Antarctic Study, NASA, Environment Canada,
UNEP, EPA and other sources as stated and credited Researched by Charles
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