There has been a recently reported die-off of bee colonies that has
been called serious in some parts of the United States; yet in other
areas, beekeepers have not been affected. It has not yet been reported in
Illinois, although it has been reported in several midwestern states. This
is a threatening situation to beekeepers, as well as those who grow and
consume many fruits and vegetables that are primarily pollinated by honey
bees. This situation is being called Colony Collapse Disorder (CCD).
Similar situations have been labeled in the past as Spring Dwindling, Fall
Collapse, Autumn Decline, May Disease, or Disappearing Disease. The term,
Colony Collapse Disorder, is being used instead for a variety of reasons,
including that the situation is not necessarily associated with any
particular time of the year and that it is not known whether a
disease-causing pathogen is involved.
Symptoms of Colony Collapse Disorder
1. In collapsed colonies:
a. The complete absence of adult bees in colonies, with no or little
build-up of dead bees in the colonies or in the front of those
colonies,
b. The presence of capped brood in colonies,
c. The presence of food stores, both honey and bee bread. These food
stores are not robbed by other bees. When hives are attacked by common
hive pests such as wax moth and small hive beetle, the attack is
noticeably delayed.
2. In cases where the colony appears to be actively collapsing:
a. An insufficient number of worker bees is present to maintain the
brood.
b. The workforce seems to be made up of young adult bees.
c. The queen is present.
d. The cluster is reluctant to consume provided feed, such as sugar
syrup and protein supplement.
Other than general symptoms, essentially nothing is known about the
causative agent. Consequently, everything becomes suspect. Nutrition
shortages, viral infections, bacterial infections, genetic paternity
conflicts, chemical misuse, high mite populations, digestive diseases,
amoeba infestations, immune system failure, and fungal infections are
common suggestions for possibly causing the unexplained colony
deaths.
One possible cause that is being investigated is the impact of
pesticides on honey bees, particularly the insecticide imidacloprid. This
insecticide is widely used to control insect pests of fruit, vegetables,
turf, and landscape plants. It is sold as Merit, Marathon, Provado,
Admire, and Gaucho. There is research indicating that honey bees that
contact imidacloprid can lose their memory of where their hive is located.
This feature is being used by some to explain why CCD-affected hives have
no bees in themthat the bees left to forage and never returned to the
hive.
However, even though imidacloprid is systemic and moves through the
plant, it is known to not get into the flowers of a number of plants. With
bees primarily visiting flowers, there are questions as to how the bees
would pick up the imidacloprid. Another question is when the honey bees
pick up the imidacloprid. Many imidacloprid-treated crops finish flowering
by midsummer, allowing time for seed or fruit to be produced and ripen
before frost. Honey bees tend to feed in late summer and fall on
late-season flowers such as goldenrod and native asters. These plants tend
to be most numerous in noncrop areas where insecticides are unlikely to be
applied. If the bees died earlier in the season from visiting flowering
crops, beekeepers surely would have noticed this when they collected honey
from the hives.
There have been media reports that this new problem may have been
ongoing for 3 to 4 years. The numerous general symptoms combined with the
broad timeframe become encompassing enough to include nearly any dead
colony. It is important that hysteria does not overtake scientific
investigation. Apparently, CCD has so far been found in bees that have
been recently stressed, that is, bees that have been moved to different
locations. The problem is being found primarily with migratory commercial
beekeepers. In discussions of CCD characteristics, it is frequently said
that hobby beekeepers are not as observant as commercial beekeepers;
consequently, their colonies that recently died were simply counted as
mite-afflicted or caused by a poor queen. However, many hobby beekeepers
are very obser-vant of their hives and would have readily observed
symptoms as those exhibited by CCD, especially if it had been going on for
several years.
Factors to consider when thinking about CCD include the
following.
- Honey bees, though they appear to be domesticated, are nonetheless
wild animals.
- As wild animals, bees are easily stressed as we manage and
manipulate colonies for our human good.
- Stressing bee colonies with migratory activity and general colony
manipulation upsets the colony's natural resistance to diseases and
pests, making them more vulnerable, not more resistant, to being overrun
by a pathogen outbreak.
- Such an outbreak can have multiple causes, thereby clouding the root
cause, colony stress, resulting in conditions like that called Colony
Collapse Disorder.
- Chemical treatments are only shortterm fixes for any bee disease.
One should always expect side effects from the use of any chemical in
bee colonies, particularly honeycomb contamination.
- The configuration of a modern hive and the configuration of a bee
yard are designed for human convenience and are not necessarily
conducive to natural honey bee biology.
- Abnormal concentrations of colony numbers and equipment only serve
to concentrate and homogenize bee diseases and pests.
- Most of the time, the best thing a beekeeper can do for a bee colony
is leave it alone.
A recent survey (March 14 to 19, 2007) of Ohio beekeepers found that on
average there was a 72% loss of live colonies from September 2006 until
March 2007. A closer breakout indicated that beekeepers with fewer than
100 colonies had an average 55% loss, those with 100 to 500 colonies
averaged 67%, and those with over 500 colonies averaged 75% loss. There
did not appear to be any difference by area of the state. Perhaps the
reason why the percentage of loss as the size of operation increases is
due to the amount of time spent by the beekeeper per colony. At one time,
a 10% or less loss was considered normal, but when parasitic mites became
common, that number rose to nearly 30%. The 72% is an unheard of
amount.
It is difficult to determine what caused the loss of so many colonies.
Fall of 2006 in most parts of Ohio had a dearth of nectar, resulting in
poor diets for the honey bee colony. In some cases, the queen reduced
egg-laying due to the dearth of nectar, resulting in older bees in the
colony and a reduced population. Many beekeepers fed their bees, but it
may not have been the proper diet. With various medications being used by
the beekeeper to control mites and disease within a colony, perhaps these
medications are reacting with each other and affecting the bees. As
beekeepers breed bees to resist mites, perhaps they are also affecting bee
longevity. There are a number of other factors that could also be related,
all of which need to be considered when thinking of CCD. In the
above-mentioned survey, the two most often cited reasons beekeepers
believed to be the cause of their loss were starvation and small clusters.
They believed both of those were brought on by the fall of 2006.
A study group called the CCD research group (comprised of university
researchers, state and federal regulatory officials, Cooperative Extension
educators, and industry representatives) is working to determine if the
cause is related to chemicals, management, breeding stock, environmental,
bee stress, or some other factor. The CCD group and Bee Alert Technology
are requesting that beekeepers fill out the National Bee Loss Survey,
which can be found at http://www.beesurvey.com. This survey
can be filled out beekeepers with operations of any size, whether or not a
loss has been suffered; the more information obtained, the better the
chance of finding a cause.
If historical precedent holds true, a causative agent will not be
found. Disturbing a colony for no reason other than to see if it is dead
from CCD will only hinder the colony. If historical precedents hold true,
with the arrival of the spring season, the symptoms will fade into
remission. Although the situation is frustrating, no one knows the cause
or the scope of this disorder. Don't panic and do question much of what
you hear.
(Phil Nixon, primarily modified from the CCD research group Web site
and articles by James E. Tew and John Grafton in the February and March
issues of the Ohio Info Bee newsletter.)
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