FILENAME:  APRAPIS.92
 
            Florida Extension Beekeeping Newsletter
    Apis--Apicultural Information and Issues (ISSN 0889-3764)
                 Volume 10, Number 4, April 1992
 
                     REGISTRATION LAW PASSES
 
It is now official.  Effective July 1, 1992, Florida's Beekeeper
Registration Fee will go into effect.  The bill implementing the
fee was passed by the legislature and the Division of Plant
Industry, Florida Department of Agriculture and Consumer Services
is now setting up a proposed fee structure.  The final fee schedule
will be somewhat different than that published in the October 1991
APIS, beginning with a $5.00 fee for one to five hives and capped
by a $100.00 charge for 5,000 or more colonies.
 
Once the Commissioner of Agriculture approves the proposed fee
schedule, it will be published for comment in Florida Weekly.  In
addition, the Honey Bee Technical Council will be asked to submit
comments.  If you are interested in the final wording, contact any
member on the Council (I am one).  For a list of members and/or
more information, contact Mr. Laurence Cutts, Chief Apiary
Inspector, Division of Plant Industry, P.O. Box 147100,
Gainesville, FL 32614-7100, ph 904/372-3505, ext. 128.
 
                       LYME DISEASE UPDATE
 
According to the newsletter of the Florida Mosquito Control
Association (Buzz Words, April, 1992), there were 9344 cases of
Lyme disease reported in 1991 versus 7943 in 1990.  In Florida, the
number of diagnoses went from seven in 1990 to 35 in 1991.
However, the Communicable Disease Center in Atlanta does not
consider the disease endemic in Florida and it is not yet a
reportable disease in the state.  Lyme disease continues to be
poorly understood and little research on potential vectors is being
conducted.
 
As the active tick season approaches in Florida, beekeepers should
keep in mind that the disease is tick borne and know its symptoms.
The February, 1992 issue of APIS contains detailed information on
Lyme disease.
 
                        VARROA DETECTION
 
The rest of the United States is starting to realize what many
beekeepers in Florida have learned in the last two years.  Varroa
mites are here to stay and monitoring the mite population is the
best way to keep parasite populations low.
 
Dr. Eric Mussen in his January/February 1992 issue of From the UC
Apiaries published a piece called "Varroa Getting Nasty."  It seems
many beekeepers in California got a surprise when their colonies
collapsed last fall.  The symptoms at first seemed to be classical
for tracheal mites:  1. rapid loss of adults;  2.  tiny clusters of
bees with a queen; and 3. abundance of stored honey and pollen.
Not characteristic was varying amounts of capped brood.  The latter
revealed that something else was going on; the adults were not
being replaced.  Developing pupae were killed in their capped cells
by mites and never emerged.
 
To prevent colony collapse, Dr. Mussen suggests checking bees for
Varroa two to four times per year.  Finding a mite or two doesn't
mean the colony is in immediate jeopardy, but it will require
treatment sooner or later.  And if another check, not too much
later, turns up a lot of mites, then you are the unlucky recipient
of someone else's failure to detect a problem.  Choose your method
of colony examination (ether roll, tobacco smoke, Apistan), he
concludes, early detection is critical to colony protection.
 
"Looking for trouble," is the way Dr. Roger Morse categorizes the
perpetual hunt for Varroa in the April, 1992 issue of Gleanings in
Bee Culture.  He concludes, "...in all probability every beekeeper
in the continental U.S. and Canada will have infested hives within
two to four years."  He recommends, therefore, that beekeepers in
the U.S., Canada and Mexico check colonies for Varroa at least
twice a year.
 
Although it has been reported that colonies sometimes take years to
die after being infested with Varroa, there are exceptions.  Dr.
Morse speaks of a New York beekeeper whose hives produced over 100
pounds of honey in July and August, yet were dead by late fall.
And Dr. Mussen describes a California beekeeper, who after a good
producing season, saw 75% of his colonies severely damaged or dead
by Christmas.  That beekeeper is no longer in business and had to
sell out at submarket prices.  These cases may be because of drift
by bees from nearby heavily infested apiaries that were not
treated.  Also the fact that mites are hidden and protected in
capped brood cells may mean a serious undercount in those found on
adults or in bottomboard debris.
 
Fortunately, detecting Varroa is a fairly simple process.  A number
of methods are described by Dr. Morse, including:  examining brood
or adults; sorting through bottomboard debris; and using the ether
roll.  These are well documented in Varroa Mite Detection, VT 249,
produced here at the University of Florida.  I can have a copy made
and sent upon receipt of a blank VHS videotape.
 
The technology to determine when a Varroa infestation reaches a
treatable level by any detection method currently in use has not
been well worked out.  Detection results may vary and are dependent
on bee/mite population dynamics.  For example, in the fall, Dr.
Morse says, with little or no brood, you are more likely to find
mites on adults, whereas in the spring they will be easier to find
in brood.  Practical experience by the Florida Division of Plant
Industry indicates that when 20 mites in an ether roll of
approximately 300 adult bees are found, a colony should be treated
with Apistan.   However, Dr. Harvey Cromroy of the Entomology-
Nematology faculty, University of Florida, believes more than five
mites is a treatable level.  Dr. Morse concludes finding 30 to 40
mites per hundred bees (ether roll) is serious and the colony may
be beyond saving.  The ability to correlate ether roll with other
detection methods is not presently available.
 
                    FLUVALINATE PROS AND CONS
 
Recently, I've taken to answering questions about the impact of
Varroa in Florida by saying there is no problem.  This raises a few
eyebrows, but in fact with widespread use of Apistan (R), the
Varroa problem is under control.  And if colonies are not treated
by a beekeeper, he/she very shortly has no bees and is also
eliminated from the "problem" category (see the article above).
 
Beekeepers in the U.S. and elsewhere, especially where Varroa was
introduced from 1987 on, are extremely lucky.  That's because by
that year a technology to effectively treat colonies for mites was
developed.  The formulation was fairly benign to humans and had
little potential to contaminate honey.  In summary, the development
of fluvalinate-impregnated Apistan (R) plastic strips has caused a
predicted disaster in beekeeping to become no more than another,
admittedly onerous and expensive, management task.
 
A recent article, however, by Israeli authors Yossi Slabezki, Hani
Gal and Yaacov Lensky in Bee Science suggests that Varroa control
based on fluvalinate is not without its problems.  Writing in
Volume 1, No. 4 of the October, 1991 issue, the authors discuss
effects of long-range usage of fluvalinate with reference to honey
contamination and sub-lethal effects on bee populations.  Two
procedures in the study were used that are not legal in the U.S.
and so will have little direct correlation with methods used in
this country:  (1)  colony infestation level was established by
fumigation with fluvalinate smoke strips; and (2) treatment was
with Mavrik (R)-soaked plywood inserts, not Apistan (R).  In spite
of this, however, the study has direct implications for beekeeping
in the U.S.  Here are some of the recorded observations:
 
"In most colonies the mite infestation level was reduced from
several hundred to 0-10 mites/colony.  However, out of each group
of 30-40 colonies, one or two still had 30-60 mites/colony."
 
"Mite populations increased during eight months in all three
climatic zones, reaching the highest levels in the hottest region.
The different population levels of Varroa mites, however, may not
only be due to temperature but to the availability of nectar and
colony strength at a particular site."
 
"Monitoring Varroa populations in a bee yard was useful for
subsequent selective control only in heavily infested colonies...If
the three (most heavily infested) colonies had then been
selectively treated against Varroa, the build-up to a population
reaching an average of 256 (+/- 21.3)/colony (in the other hives)
might have been prevented."
 
"Long-term treatment (6 to 8 months) with fluvalinate inserts
...resulted in an almost zero level of Varroa ...Short-term (6
weeks) exposure resulted in increased mite populations.  There were
no significant differences in the populations of brood and adult
bees between the colonies that were exposed to (fluvalinate) 6
weeks or 6 to 8 months.  However, the average honey yields per
colony were 7 to 15 kilograms (1kg = 2.2 lbs) higher from
colonies...exposed to fluvalinate for the shorter interval."
 
"No detectable residues were found in samples of honey removed from
colonies exposed to fluvalinate for 6 weeks.  However, in honey
samples removed from colonies exposed...for 6 months, the
level...reached 0.06 +/-0.05 ppm (parts per million)...above the
level established in the U.S. by the EPA."
 
"In beeswax, fluvalinate residues were higher than found in honey.
They reached 0.83 +/-0.77 ppm...in colonies exposed to fluvalinate
for 6 months, compared to 0.54 +/-0.21 ppm in wax samples obtained
from colonies exposed to fluvalinate for six weeks."
 
"The placement of fluvalinate inserts at the entrance or inside the
brood nest resulted in efficient Varroa mite control in both
treatment groups.  By placing fluvalinate inserts at some distance
from the brood nest combs and by removing them after six weeks, we
minimized or eliminated fluvalinate contamination of honey and
beeswax."
 
"Under the subtropical conditions of Israel, where egg-laying and
brood rearing by honey bees is year-round...two treatments per
colony per year are sufficient to keep Varroa mites below a level
of economic damage."
 
"By monitoring colonies for mite populations...we were able to
selectively treat only highly infested colonies...to reduce both
the number of treatments and the amount of acaricide used in the
apiary."
 
"Sublethal doses of...insecticides, including pyrethroids
(fluvalinate is classed as a synthetic pyrethroid) have been shown
to modify mating, feeding, and other insect behavior."
 
"While a beekeeper may feel that extended treatment might provide
prolonged protection from Varroa mites, our data indicate that it
will result in reduced honey yields and honey and beeswax
contamination at levels above established tolerances."
 
"Fluvalinate residues in wax from bee colonies that had previously
been treated with two Apistan (R) strips...may be due to the
increased surface area...250mm X 30mm X 2 strips, which is about
five times greater than that of a plywood insert (180mm X 20mm) as
well as increased amounts of active ingredient per treatment."
 
"In Israel, honey is extracted only from full-depth supers that are
separated from the brood nest by a queen excluder.  Even though
fluvalinate has been used for three and a half years, no traces of
the compound have been found in samples of honey in the
marketplace."
 
The authors conclude that beekeepers should be able to reduce the
frequency of fluvalinate treatments by carefully monitoring their
colonies for mites and only treating those which exceed a certain
threshold level.  They also state that the possibility of reducing
strip surface area and placing strips at the colony entrance could
lead to changes in fluvalinate treatment practices.  The closing
statement: "...development of alternate acaricides, especially
those from plant origin, would permit the beekeeper to alternate
treatment products, thus extending the life of fluvalinate as a
part of an integrated control program for Varroa jacobsoni."  If
anyone wishes to read the full text of the paper, I will mail one
on request.
 
As an epilogue to this study, several qualifying statements must be
made.  Work at the University of Florida suggests that treatment
strips (plywood or plastic) on the bottom board are prone to get
wet, even wash away, during rainstorms; placement on the top bars
has not been found to be effective.  Although less active
ingredient is found in Mavrik (R)-soaked plywood inserts, there is
evidence that more fluvalinate is released from the wood strips
earlier and less later as treatment proceeds.  This suggests that
plywood, or treatment using any other carrier (e.g. paper
toweling), is much more variable than Apistan (R) formulated on
slow-release plastic.  The above study reveals, for example, that
colonies treated for six weeks with plywood inserts had a
resurgence in mite populations and the treatment was not uniform in
killing mites in all colonies.  As far as I can tell "established
tolerances" referred to in the study have yet to be fully
determined.
 
Although many continue to believe that they are paying too much for
Apistan (R), the benefits beekeepers are enjoying (research and
development costs as well as expenses involved in making the
material legal to use) are very real.  It means a lot to the
industry to have a material that, when used according to the label,
is certified effective for mite control as well as safe in
protecting the honey crop from contamination.  As the authors of
the above study conclude:  "Because beeswax retains fluvalinate
residues, because honey and section-honey enjoy a 'natural food'
image and because Varroa mites may develop resistance...in the
future, it is in the beekeeper's best interest to carefully apply
fluvalinate."
 
 
Sincerely,
 
 
 
Malcolm T. Sanford
Entomology-Nematology, Bldg 970
University of Florida
Gainesville, FL 32611-0620
Phone (904) 392-1801, Ext. 143
FAX: 904-392-0190
BITNET Address: MTS@IFASGNV
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