Adding to the thread on tracheal mite history:
 
From the pages of APIS
<http://www.ifas.ufl.edu/~mts/apishtm/apis85/apmay85.htm#1>, May 1985
 
TRACHEAL MITES--TO EXPERIMENT OR NOT TO EXPERIMENT
 
[Editor's note 5/11/1997--this presaged the arrival of the Varroa mite; much
of the information is relevant for both tracheal
and Varroa. Tracheal mites have all but disappeared in Mexico; one possible
reason is that treatment was never used and
only the resistant strains survived. The arrival of the African bee also
introduces more variables in that country.]
 
Beekeepers have always been experimenters. And there's little doubt this
kind of study has advanced the craft
considerably over the centuries. The tradition continues as the current
confusing situation over tracheal mites persists. I
have heard that a number of beekeepers are experimentally treating colonies
with a wide range of chemicals in order to
"control" mite infestations. The reasons why experienced bee researchers and
others blanch at the thought are legion. They
range from a wish to obtain for themselves highly infested colonies, not all
that common, for study that have not been
tampered with, to fear for the experimenting beekeeper's safety.
 
Many persons are understandibly frustrated by the apparent lack of research
going on to control tracheal mites. That's
particularly true for those in already infested areas (now offically all of
Florida) as opposed to others who stubbornly assert
that no mites exist in their states or operations. Beyond the politics of
the situation, however, lies the real world of making
the kind of research decisions needed that lead to effective solutions.
 
Dr. Elbert Jaycox has recently written an article in his beekeeping
newsletter that points out some of the major kinds of
decisions that must be made as research begins on chemical compounds for
possible use either in quarantine or field
treatments of infested bees. First and foremost, Dr. Jaycox says, relates to
the type of material to use--fumigant or
systemic. Fumigants must be able to disperse widely within a colony and
penetrate the breathing tubes of all the bees in a
colony to kill mites. Systemics are chemical compounds fed to bees that must
be eaten, absorbed by the bees and then kill
mites that feed on the bees blood (haemolymph). To be useful, he continues,
both fumigant and systemics must kill the
mites without killing many bees and not leave toxic residues which
contaminate honey or wax.
 
Historically, Dr. Jaycox says, fumigants have been relied on for tracheal
mite control. In at least one case, they have killed
infested bees, weakening a colony. Many materials have killed all the mites
in lightly infested colonies, but have rarely been
effective when bees are heavily infested. The reasons include: (1) the
fumigant doesn't reach all bees; (2) when it does
reach all bees, it doesn't reach all the mites. Their may be as many as
eighty adult mites, thirty-one larvae and eight eggs in
a single bee. These can plug the breathing tubes (tracheae) so the fumigant
will not enter. In addition, mites may be located
deep inside an individual bee. They have been found in the smaller branches
of the trachea and in air sacs in the head.
According to Dr. Jaycox, therefore, "Probably because of these problems, Dr.
Wolfgang Ritter and his associates in
Germany found that colonies treated eight time at 4- to 7-day intervals with
Folbex VA (bromopropylate) still contained
bees infested with live mites."
 
Additional problems posed by fumigants, according to Dr. Jaycox, include
differing resistance of mite eggs, larvae and
adults. Because eggs are so difficult to kill, two fumigant treatments,
timed to allow eggs to hatch, have better chances at
control than one. In order to kill all mites in package bees, for example,
Dr. Jaycox says they will probably have to be
stored four to seven days and treated twice with effective miticides. This
added expenses for the producer must also be
passed on to the consumer.
 
Systemic treatments for mites allow for closer control of dosage than using
fumigants, Dr. Jaycox says, and they also
reduce possibility of contamination of hive bodies, frames, and wax. At the
same time however, chances of leaving residues
in honey increase, because nectar is processed by materials added by
individual bees themselves. Not giving enough
chemical to bees can also result in creating resistant strains or mites,
according to Dr. Jaycox, which has already been
observed with the use of phenothiazine in Japan.
 
If one carefully examines the above, it can be inferred that quality
effective research on tracheal mites is no easy task. A
great number of questions need to be answered. In infested bees, are the
mites killed and not the bees? How many? All?
How can it be shown they are actually dead? Remember, to evaluate a study
requires infested bees be laboriously
dissected and examined under a microscope by trained persons. In addition,
any experiment that appears to work, must be
repeatable to ensure reliability. Given that specific bees are destroyed to
determine if materials are killing mites, it must be
proven that repeat experiments are not somehow effected by bees removed
during earlier trials.
 
Finally, no experiment is worth much without a control, an untreated colony
in the exact same state genetically, qualitatively
(same stores, amount of brood) and infested to the same degree as the colony
being treated. This provides the basis for
comparison to show a material's effectiveness. In bee research, developing
effective control colonies is often the most
difficult part of an experiment. This is because to be shown to be generally
effective, experiments must usually be
conducted on a large scale involving a great number of both infested and
control colonies.
 
Does all this mean that experimentation with tracheal mites is something
best left to the "experts. Not necessarily. Without
resorting to chemicals, the beekeeper has at his/her disposal all the
material needed to effectively and safely experiment
with controlling mites--the honey bee's variable genetic complement.
Selecting colonies that appear to be resistant and then
propagating queens from them is an age-old scheme that has been shown to be
effective in controlling American foulbrood,
swarming, and pollen collecting.
 
Dr. Jaycox indicates that having bees resistant to mites would reduce losses
and need for treating with chemicals. For
example he mentions F.W. Calvert in England who has claimed that bees of the
Buckfast strain could eliminate a mite
infestation within twelve months and would prevent reinfestation.
Unfortunatley, Dr. Leslie Bailey of Rothamsted
Experimental Station was unable to confirm this resistance in Buckfast bees.
A Beowulf Cooper, also of England, Dr.
Jaycox says, reported he continually selected breeder queens from colonies
resistant to mites and killed all infested
colonies but one every winter. He used that one to infest the rest of the
colonies in the spring as a continual selection
process for resistance.
 
Selecting for resistance is not an "exact" science. Rather, it is more of an
estimate of the state of a colony because the
specific genetic links that might cause resistance are not known. All the
beekeeper can go on is whether a colony seems to
be somehow better off than others in a specific setting under specific
conditions. Brother Adam at Buckfast Abbey, for
example, appears to select his mite- resistant colonies on the basis of
whether or not they overwinter. This is over simplistic
to be sure because many things besides mites will affect overwintering
capability, but given so little knowledge of the
specifics of mite resistance, it is elegantly simple and apparently effective.
 
Selecting for genetic resistance is a far more forgiving and natural (some
might even call it "organic") way to experiment
without having to resort to potentially environmentally harmful chemicals
and their possible complications. Dr. G.P.
Georghiou, known worldwide for expertise in the area of insect resistance to
pesticides and now retired from the
University of California, has said that neither use of chemical toxicants
nor development of resistance to chemicals by pest
insects is recent. Life forms possess natural defense mechanisms to repel
attacking organisms, developed over million of
years of evolution. This is not only true for insect pests, but also for
weeds and plant diseases, where chemicals have been
developed for control. Some 447 insect species, 100 plant pathogens, 48
weeds and two species of nematodes are now
resistant to chemical pesticides.
 
In a recent series of articles in Agrichemical Age, A.D. LaFarge looked at
pesticide resistance that has been building up in
insects ever since D.D.T. was developed. She dubbed this the "Evolutionary
Squeeze." A dramatic example of resistance
is found in the Colorado potato beetle, which has, "weathered the onslaught
of arsenicals, chlorinated hydrocarbons,
organophosphorous compounds, carbamates and pyrethroids."
 
Chemical manufacturers are also feeling the squeeze, according to Ms.
LaFarge, who says that rate of introduction of new
pesticides declined to almost nil between 1970 and 1980, while costs to
develop a new chemical have risen from $1.2
million in 1956 to $30 million in 1984. For insect pest species, therefore,
the most pressing future question is how to
control pest populations as more and more become resistant to pesticides.
The beekeeper would do well to look closely at
the corrollary; that the perceived "problem" for pest species may be the
best potential "answer" for maladies that affect
honey bees. Indeed, it appears the beekeeper who continually experimentally
selects stock for resistance to mites,
chalkbrood, and European foulbrood will be way ahead of even the "experts"
in knowledge and experience, if and when
Varroa mites or Africanized honey bees arrive in this country.
 ==============================================================================
Dr. Malcolm (Tom) Sanford, Extension Apiculturist, University of Florida
Bldg. 970, P.O. Box 110620, Gainesville, FL 32611-0620
Ph. 352/392-1801 ext. 143   Fax 352/392-0190
E-mail: [log in to unmask]
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