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 Copyright
 Introduction
 Life cycle of varroa
 Control strategies
 Chemical control
 Honey contamination
 Control by management/manipula...
 Sampling for mites






Group Title: Fact sheet - Florida Cooperative Extension Service, University of Florida - ENY-127
Title: The varroa bee mite
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Permanent Link: http://ufdc.ufl.edu/UF00077129/00001
 Material Information
Title: The varroa bee mite
Alternate Title: EDIS
Physical Description: Book
Language: English
Creator: Sanfor, Malcolm T
Publisher: University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication: <Gainesville Fla.>
Publication Date: <1992>-
 Subjects
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
System Details: Internet access required.
Statement of Responsibility: Malcolm T. Sanford and H.L. Cromroy.
General Note: At head of title: University of Florida, Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS.
General Note: "This document was published November, 1992 as ENY-127, and supercedes "Hints for the Hive" No. 127, Florida Cooperative Extension Service. For more information, contact your county Cooperative Extension Service office."--Footnote.
General Note: Title from web page viewed on November 26, 2001.
Funding: This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Florida Sea Grant technical series, the Florida Geological Survey series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources.
 Record Information
Bibliographic ID: UF00077129
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: aleph - 002736819
oclc - 48479938
notis - ANL4634

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Table of Contents
    Copyright
        Copyright
    Introduction
        Page 1
    Life cycle of varroa
        Page 2
    Control strategies
        Page 2
    Chemical control
        Page 3
    Honey contamination
        Page 4
    Control by management/manipulation
        Page 4
    Sampling for mites
        Page 5
Full Text





HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida













The Varroa Bee Mite1


Malcolm T. Sanford and H. L. Cromroy2



Varroa jacobsoni is potentially the most serious
pest ever to threaten world beekeeping. Reports
from other areas where the mite has been introduced
show that great losses of colonies have occurred. The
same has been true in the United States.

It is important to ensure that Varroa is not
confused with the honey bee tracheal mite (Acarapis
woodi). There has been and continues to be a great
deal of controversy about the latter mite which lives
in the breathing tubes of bees. The tracheal mite is
difficult to find and the damage it inflicts on colonies
is a matter of great debate. The Varroa mite should
also not be confused with the bee louse, Braula coeca,
which has six legs that extend from the body (Figure
1).


The Varroa mite, by contrast, is an external
parasite of the honey bee. It is visible to the naked
eye (Figure 2), reddish brown with a characteristic
oval shape and has eight legs tucked under a shell
(Figure 3).

Some generalizations concerning the Varroa mite
which have been true in other infested areas of the
world are:

1. Russian and European experiences reveal an
infestation is usually fatal to colonies of European
bees (Apis mellifera) within three to seven years.

2. Low levels of infestation are extremely difficult to
detect.


Figure 1. Bee louse. (SEM photo by H. L. Cromroy and
W. C. Carpenter.)

3. It is a 7-10 year process to get chemicals
registered, a process often costing millions of dollars.

4. Many of the 140 or so chemicals used worldwide
for Varroa mite control are toxic to bees and
beekeepers and their use risks contamination of
honey and wax.

5. The Varroa mite develops resistance to chemicals
in a short time. This is especially true when the
chemicals are not used properly and/or dosage rates
have not been adequately investigated.


1. This document was published November, 1992 as ENY-127, and supercedes Hints for the Hive No. 127 Florida Cooperative Extension Service.
For more information, contact your county Cooperative Extension Service office.
2. Professor, Department of Entomology and Nematology, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University
of Florida, Gainesville.

The Institute of Food and Agricultural Sciences is an Equal Opportunity/Affirmative Action Employer authorized to provide research, educational
information and other services only to individuals and institutions that function without regard to race, color, sex, or national origin.
Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences / University of Florida / John T. Woeste, Dean







The Varroa Bee Mite


Figure 2. Adult female, ventral and dorsal views, comparing size with hind leg of worker honey bee. (SEM
photo by H. L. Cromroy and W. C. Carpenter.)


Based on the above information, several things
are apparent. The Varroa mite is a serious pest
leading to death of European bees in most cases.
Mite populations are difficult to detect in incipient
stages, and may take years to build up to levels where
colony death is imminent.

LIFE CYCLE OF VARROA

Numerous studies have pieced together the life
cycle of the Varroa mite (Figure 4), but it has yet to
be cultured artificially and many aspects of its
complicated biology are unknown. The adult female
leaves the brood cell and attaches to an adult worker
or drone where she begins to feed by cutting a hole in
the intersegmental membrane of the bee's hard outer
skeleton. Little is known about the length of time
required for this phase. Next, the well-fed female
drops off the adult into a brood cell and hides in the
brood food (jelly).

Normally, once the brood food is consumed by
the host, the female then begins to feed on the larvae
itself by piercing its delicate skin. She then lays a
number of eggs of both sexes which hatch into six-
legged larvae. After 48 hours, these become eight-
legged protonymphs which, after feeding on the bee
larva, molt into a deutonymph. Three days later, the


last molt to an adult occurs. Approximately twenty-
four hours later the mites mate inside the capped
honey bee brood cell. The males die after copulation
in the brood cell and the female mites emerge to
begin the cycle again.

The female mite does not lay its eggs all at once,
but at prescribed intervals (See Figure 4). This
means that the longer the brood cycle, the more time
there is for subsequent mites to develop. It is thought
that drones are preferentially parasitized because
their developmental cycle is longer (24 days) than that
of the worker (21 days). It is also believed that bees
with shorter developmental times [Apis mellifera
scutella, the African honey bee, and the Asian bee,
Apis cerana (Indica)] are more resistant to Varroa
because mite populations do not develop as quickly as
in the European races.

CONTROL STRATEGIES

Control of the Varroa mite must be accomplished
using several strategies in concert with each other,
similar to integrated pest management techniques
commonly used in much of agriculture. Dr. W. Ritter
of the German Federal Republic in "Varroa Disease
of the Honeybee Apis mellifera," Bee World, Vol. 62,


Page 2







The Varroa Bee Mite


Figure 2. Adult female, ventral and dorsal views, comparing size with hind leg of worker honey bee. (SEM
photo by H. L. Cromroy and W. C. Carpenter.)


Based on the above information, several things
are apparent. The Varroa mite is a serious pest
leading to death of European bees in most cases.
Mite populations are difficult to detect in incipient
stages, and may take years to build up to levels where
colony death is imminent.

LIFE CYCLE OF VARROA

Numerous studies have pieced together the life
cycle of the Varroa mite (Figure 4), but it has yet to
be cultured artificially and many aspects of its
complicated biology are unknown. The adult female
leaves the brood cell and attaches to an adult worker
or drone where she begins to feed by cutting a hole in
the intersegmental membrane of the bee's hard outer
skeleton. Little is known about the length of time
required for this phase. Next, the well-fed female
drops off the adult into a brood cell and hides in the
brood food (jelly).

Normally, once the brood food is consumed by
the host, the female then begins to feed on the larvae
itself by piercing its delicate skin. She then lays a
number of eggs of both sexes which hatch into six-
legged larvae. After 48 hours, these become eight-
legged protonymphs which, after feeding on the bee
larva, molt into a deutonymph. Three days later, the


last molt to an adult occurs. Approximately twenty-
four hours later the mites mate inside the capped
honey bee brood cell. The males die after copulation
in the brood cell and the female mites emerge to
begin the cycle again.

The female mite does not lay its eggs all at once,
but at prescribed intervals (See Figure 4). This
means that the longer the brood cycle, the more time
there is for subsequent mites to develop. It is thought
that drones are preferentially parasitized because
their developmental cycle is longer (24 days) than that
of the worker (21 days). It is also believed that bees
with shorter developmental times [Apis mellifera
scutella, the African honey bee, and the Asian bee,
Apis cerana (Indica)] are more resistant to Varroa
because mite populations do not develop as quickly as
in the European races.

CONTROL STRATEGIES

Control of the Varroa mite must be accomplished
using several strategies in concert with each other,
similar to integrated pest management techniques
commonly used in much of agriculture. Dr. W. Ritter
of the German Federal Republic in "Varroa Disease
of the Honeybee Apis mellifera," Bee World, Vol. 62,


Page 2







The Varroa Bee Mite


Figure 3. Adult female, showing curvature of body and legs covered by the shell. (SEM photo by H. L. Cromroy
and W. C. Carpenter


No. 4, 1981, pp. 141-153) suggests a combination of
the following:

1. Develop and use more effective treatment
methods.

2. Control importation of all species of honey bees.

3. Diagnose infestations in the latent stage (before
damage is seen).

4. Isolate infested colonies and those in the
immediate area.

5. Control and coordinate treatment of infested
colonies.

According to Dr. Ritter, the aim in the German
Federal Republic has been to isolate the source of
infestation and eradicate the mite in specific localities.
However, where it has been spread over a wide area,
infestation can at best only be reduced, particularly
where there are feral colonies.


He also states that unsuitable highly toxic
substances are coming into use and their improper
application can contaminate honey. Frequent
underdosing can also result in resistant strains of
mites, already observed in Japan with phenothiazine.
Frequent use of chemicals can also make beekeeping
unprofitable, says Dr. Ritter, and a biological control
should be a first priority in research for a long-range
answer to Varroa control.

CHEMICAL CONTROL

Using chemicals to reduce mite populations can
in no way be compared to experiences by beekeepers
with Terramycin@ to control American foulbrood.
Therefore, beekeepers are urged not to use chemicals
for mite control unless they are registered. Not only
is the practice of using unregistered pesticides illegal,
but it can also create undesirable effects. Among
these are chemically-resistant mites, contaminated wax
and honey, and susceptible lines of bees which are
more prone to parasitization.


Page 3








The Varroa Bee Mite


Development of the bee brood Day
Queen lays egg Egg phase 1
2
3
Larva phase 4
5


Cuncapped brood) 7
8
9
Pupa phase 10
11
12
13
14
Capped brood) 15
16
17
18
19
201
Emergence of worker bees 21 1


Mite lays 4 eggs in the brood cell:
1st egg 2.5 days after entering cell
2nd egg 1.25 days later
3rd egg 1.25 days later
4th egg 1.25 days later


Development to sexually
mature mites:
Female; 7 to 8 days
Male; 6 to 7 days


Figure 4. Life Cycle of Varroa Bee Mite.


Again, it is emphasized that USE of any
unregistered chemicals by beekeepers is potentially
HARMFUL to the beekeeping industry. It should be
remembered that chemical control can only be
considered a short range objective--more long-range
research will be required to find suitable biological
control and/or resistant strains of bees.

HONEY CONTAMINATION

Although pesticide use may be impermanent, or
at best, changing as more and more chemicals are
used for mite control, it is a certainty that more and
more honey will be screened for chemical
contamination in the future. Should pesticide
contamination be found, the resulting adverse


publicity could severely damage the honey industry.
Witness the use of aldicarb on watermelons and the
Alar scare on apples. If there is a tradeoff between
mite control and contamination of honey, the bias
must be for protecting the name and reputation of
honey in the decision-making process.

CONTROL BY MANAGEMENT/
MANIPULATION

Experience has shown that Varroa mite control is
possible by reducing the mite populations through
management/manipulation. Because the mite needs
access to brood to complete its life cycle, bees can be
removed from brood (broodless times in cold climates


Page 4








The Varroa Bee Mite


Development of the bee brood Day
Queen lays egg Egg phase 1
2
3
Larva phase 4
5


Cuncapped brood) 7
8
9
Pupa phase 10
11
12
13
14
Capped brood) 15
16
17
18
19
201
Emergence of worker bees 21 1


Mite lays 4 eggs in the brood cell:
1st egg 2.5 days after entering cell
2nd egg 1.25 days later
3rd egg 1.25 days later
4th egg 1.25 days later


Development to sexually
mature mites:
Female; 7 to 8 days
Male; 6 to 7 days


Figure 4. Life Cycle of Varroa Bee Mite.


Again, it is emphasized that USE of any
unregistered chemicals by beekeepers is potentially
HARMFUL to the beekeeping industry. It should be
remembered that chemical control can only be
considered a short range objective--more long-range
research will be required to find suitable biological
control and/or resistant strains of bees.

HONEY CONTAMINATION

Although pesticide use may be impermanent, or
at best, changing as more and more chemicals are
used for mite control, it is a certainty that more and
more honey will be screened for chemical
contamination in the future. Should pesticide
contamination be found, the resulting adverse


publicity could severely damage the honey industry.
Witness the use of aldicarb on watermelons and the
Alar scare on apples. If there is a tradeoff between
mite control and contamination of honey, the bias
must be for protecting the name and reputation of
honey in the decision-making process.

CONTROL BY MANAGEMENT/
MANIPULATION

Experience has shown that Varroa mite control is
possible by reducing the mite populations through
management/manipulation. Because the mite needs
access to brood to complete its life cycle, bees can be
removed from brood (broodless times in cold climates


Page 4







The Varroa Bee Mite


may also be taken advantage of) for a period of days
by placing them in packages or empty boxes.

Adult bees removed from infested colonies can be
established on foundation or broodless comb that has
been stored for a few days and is free of mites.
Other manipulations including the use of drone
combs as Varroa traps and heat treatment of infested
combs may be useful for small-scale beekeepers.

SAMPLING FOR MITES

Beekeepers are encouraged to regularly sample
their own bee colonies for presence of Varroa in an
effort to monitor mite population. The videotape,
Varroa Mite Detection, VT 249 is available on request
by sending a blank VHS tape to Extension
Apiculturist, PO Box 110620, Bldg. 970, Gainesville,
FL 32611-0620.

Adult female mites are pale to reddish brown and
measure about 1.1 millimeters long by 1.5 millimeters
wide. The following methods are recommended for
detecting Varroa in a colony:

1. Examination of hive debris:

Collect debris from hive floor with brush and dustpan
and examine on a sheet of white paper. At least one
commercial brand of mite detection board is on the
market.

2. Examination of adult bees:

a. Collect 50 to 100 bees from open BROOD
COMB. Place in washing solution- gasoline, 25%
ethanol or isopropyl alcohol, detergent-water mixture
or hot water, and shake vigorously for 1 to 10
minutes. Recover mites by straining through fine
screen mesh.

b. Collect 100 live bees from open BROOD COMB.
Place in small cage with wire mesh bottom on white
paper. Place in oven at 46-47 degrees C. (114-1200F.)
for 10 to 15 minutes and examine white paper.

c. Put about 1.3 pint (200-300) of live bees from
open BROOD COMB in a glass jar, add a one-
second squirt of ether and alcohol (commercial
engine starting fluids can be used), shake and roll
bees around in jar. Look for mites on side of glass
jar. Mites are reddish in color and uniformly shaped.


It is emphasized that for all tests listed above, bees
samples MUST COME from the brood nest, NOT
the entrance.

3. Examination of brood cells and combs:

a. Uncap brood (drone brood is preferred by the
mites, but they can also be found on worker larvae)
and remove white pupae with forceps. The dark
colored adult mites are easily seen against the bee
larvae and/or pupae which are glistening white.

SANITATION

Although the possibility of Varroa being
transferred from one hive to another by humans is
considered slight, it cannot be totally discounted.
Adult mites have also been found on other insects,
but are not thought to be able to reproduce except in
honey bee colonies. Mites cannot live if separated
from honey bees for more than four days. Mite
infested clothing stored away from contact with bee
colonies that long will not contaminate other colonies.

DAMAGE AND SYMPTOMS

Bees in temperate climates with harsh winters
appear to be more at risk (i.e. dying from harsh
conditions--winter loss) than populations in other
climatic zones. In hot climates, where brood is reared
year around, mite populations reach their zenith
sooner than in cooler climates. In Florida, under
ideal conditions colony death can occur within 6-9
months. Most authorities agree that all European
bees (Apis mellifera) that become infested with Varroa
must be considered in extreme jeopardy.

It is emphasized that it may take a long time for
the mite population to build to levels where extensive
damage is seen. The most observed symptom of the
disease is deformed larvae, pupae and adult bees,
which are often thrown from the colony and can be
seen near the entrance.

This information was developed by a special
Varroa Mite Task Force, Division of Plant Industry,
Florida Agriculture and Consumer Services. It is
being made available electronically and in print by the
Institute of Food and Agricultural Sciences,
University of Florida.


Page 5




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