Apis--Apicultural Information and Issues
Florida Extension Beekeeping Newsletter
Volume 7, Number 10, October 1989
Certain things are better remembered than others. This concept has been on my
mind lately as I contemplate leaving Italy after a four-month faculty
development grant. Mercifully, many of the stress filled moments of setting
up living quarters in a different culture are now faint memories stuck away
deep in my brain. It is far easier to remember the impromptu meals I was
invited to, or those times when a special effort was made to help a foreigner
get a better understanding of beekeeping in Italy and how it meshed with the
A particular incident comes to mind. On the spur of the moment, after
arriving on the train from Bologna, Dr. Carlo Vidano at University of Torino
invited Christy and I to go on an outing to Monte Bianco. This large
snowcapper is one of the highest alps that separates France and Italy. During
the trip, Dr. Vidano enthusiastically pointed out landmarks like old Roman
stone supports still proping up vineyards and the large number of old castle
ruins. He, along with Prof. A. Arzone and Dr. A. Alma who accompanied us,
described in detail the characteristics of each little region as we traversed
northern Italy's Valle D'Aosta. The views all along the route, especially
those of a glacier actively calving very near the highway were spectacular.
We also went through the tunnel (one of the longest in Europe) underneath the
mountain that separates France from Italy to meet with a French colleague.
Later, we were treated to a fine lunch of local specialties at one of the
restaurants that dot the Valle D'Aosta. Finally, we visited the Alma
residence and were presented with one of the best bottles of locally vinted
During our visit, Dr. Vidano mentioned he would be traveling in the United
States in August. We were delightfully surprised, while watching CNN news
in Bologna, to view a report featuring his visit to Beltsville, Maryland. I
can still remember him animatedly talking about something dear to his heart,
biological control of insects in Italian vineyards.
While returning to Bologna last week, I was thinking about making a return
visit to see Dr. Vidano and his colleagues just before I left Italy.
Unfortunately, when I arrived, there was word that just the day before he had
suddenly died. There was no warning. He simply went to his room in the pink
of health and was found dead sometime later. I know no other details.
Presumably there will be obituaries in the Italian bee journals and "Bee
World," the organ of the International Bee Research Association (IBRA).
Dr. Vidano was active in bee work for many years. He and his group have a
worldwide reputation and a good number of publications in the field. I
reported on many of the activies at Torino in a previous issue of this
newsletter. Although he is gone now, I will always fondly remember that
spectacular summer day when I was priviledged to accompany Dr. Vidano through
the part of Italy that he knew and loved so well.
VARROA IN ITALY--THE FLORIDA CONNECTION
A major focus of my trip to Italy has been to determine how the beekeeping
industry here is affected by the Varroa bee mite. I did not expect to find a
magic solution to the mite problems facing U.S. beekeeping; there is none.
Rather, I thought that detailed information on the Italian experience might
provide some insight about the future of Varroa in Florida. As a
counterpoint, when I mentioned that the mite has been found in the U.S., many
those in Italy said they were waiting for a solution to come out of America.
A prevailing thought here seems to be that because U.S. technology can put a
human on the moon, it can also solve the worldwide Varroa problem.
Since the arrival of Varroa in Italy in 1981, a great deal of effort has gone
into searching for a solution to the problem. Many Italian papers have now
been published on the mite and the country has hosted experts meetings on
control measures. The scenario that emerges from all this is that the
situation is currently stablized. For many Italian beekeepers, the immediate
danger has passed. Several chemicals have been labelled and they are keeping
mite populations at tolerable levels.
Italy has also been active in collecting knowledge of mite infestations in
other European countries. In May, 1987, an international meeting was held in
Trento, Italy, near the Austrian and Yugoslavian border. Dr. F. Perschil from
Freiburg, Germany provided information that Varroa was introduced in 1977. It
proved impossible to contain the infestation in spite of quarantines and other
regulatory measures. Factors influencing the spread of the mite included the
fact that infestations were underestimated at the beginning and control
measures were instituted too late, unevenly and "unprofessionally." At that
time, Dr. Perschil stated it was possible to control the mite in Germany with
chemical therapy, which included Folbex VA, Illertisser mite plates (IMP) and
Perizin. Dr. R. Moosbeckhofer reported on the situation in Austria. Varroa
was spreading rapidly and several tens of thousands of colonies had died. The
same products as those for Germany were labelled in that country.
Although the Yugoslavian situation was discussed at the Trento meeting,
the text of what was said was not published in the proceedings. It is known,
however, that Varroa has been in Yugoslavia since before 1980. Dr. J.
Kulincevic in Belgrade has been working with U.S.D.A funding and assistance to
breed European bees resistant to Varroa for the last few years. It is this
stock that is being considered by for experimental introduction to an
island off the Lousiana coast by the Baton Rouge bee laboratory.
A later more comprehensive experts meeting was held in Udine, Italy, November,
1988, and the current situations in several other European countries were
described. Varroa was first discovered in Switzerland near Basel in 1984. It
rapidly spread throughout the country, except some isolated alpine valleys.
Folbex VA, Apitol, Perizin and formic acid were being used to reduce mite
populations. In Spain, the mite was first discovered in 1985 and by 1987 had
spread to all parts of the country. In Portugal it was present in all
bordering areas with Spain and on its north coast. One reason for the rapid
spread in Spain was the predominantly warm climate which allows bees to rear
brood all year long.
The Italian Varroa experience mirrors that of many European countries. After
discovery in 1981, the mite rapidly spread for a number of reasons including
trade in nuclei and queens, collection of swarms of unknown origin, beekeeping
techniques such as equalizing colonies and finally, robbing. The infestation
worsened until 1983. It is estimated that some 10 to 20% reduction in hives
occurred across the country. In southern Italy and Sardinia, 80-90% losses
were reported. By 1988, Folbex VA (brompropylate), Perizin (coumaphos) and
Apitol (cymiazole) were registered for control of the mite. Since then,
fluvalinate has been added to the Italian beekeeper's chemical arsenal.
There is now unanimity in Italy that beekeepers will have to learn to live
with the mite. It is also agreed that only an integrated approach using
breeding programs and beekeeping techniques, in conjunction with chemical
control measures will effectively control mite populations.
Unfortunately, effectiveness of control measures vary depending on climatic
conditions. Thus, no single solution will work in Italy. In the south, where
brood is reared all year around, I have been told that mites are already
showing resistance to chemicals. One researcher said that some beekeepers
have resorted to applying certain substances up to fifty times a year.
Most scientists and beekeepers believe it is easier to control Varroa in
northern Italy because there is a winter broodless period. Cultural control
methods are also showing encouraging results.
A major problem in Italy as elsewhere continues to be that of diagnosing the
beginnings of a Varroa infestation. The one thing in print I have seen
here that estimates levels of mite infestation comes from Germany. Details
were published in the recent issue of the news of the AAPI (Associazione
Apicoltori Professionisti Italiani). According to Dr. W. Ritter, cited by the
article as speaking at the VII AAPI convention in Cecina, Italy, November 26,
1988, the following table shows an approximate infestation level correlated
with natural fall of mites and the amount of drone and worker brood, and adult
bees parasitized, and colony behavior.
Natural Drone Worker
Infestation Fallen Brood Brood Adults Colony
Level Varroa Infested Infested Infested Behavior
Low Less than One Not visible Not visible Normal
Medium 5-10/day Frequent Rare Not visible Normal
High 10-15/day Almost Frequent One Normal
Very Critical Over Complete EFB like Malformation Restless
15/day symptoms Disorganized
Interpretation of the diagnostic formula above not only varies with climatic
conditions, but also with the season of the year. For example, Dr. Ritter
says, in July and August a 5% infestation of worker brood approaches the very
critical stage, whereas in September and October the percentage can rise as
high as 20% before reaching the same level. Nowhere in the article is found
a recommendation of when to chemically intervene.
Like Italy, the state of Florida was quickly overrun by mites in spite of
quarantines and other measures instituted to control their spread. Florida
beekeepers must now become aware of Varroa and realize it is a significant
beekeeping problem. This realization took several years to develop in Italy
after first detection; many beekeepers went out of business simply because
they lacked sufficient information or were not motivated to control mite
As in Italy, there will probably be different mite control strategies based on
location in Florida. The southern, tropical part of the state, where brood is
present all year around, will presumably be more effected by Varroa than the
north, where a short broodless period exists most years. The most dangerous
time for a colony in Italy has been found to be after a honey flow, when there
is a large amount of sealed brood and the queen has reduced egglaying. As
this brood emerges, many adult Varroa also exit the cells; they quickly
parasitize the remaining brood and decreased number of old adult bees, rapidly
bringing the colony to the very critical stage. This will probably also be
true in Florida.
Florida beekeepers must begin to routinely monitor mite infestation levels.
At this time, almost all beehives in Italy have been equipped with some form
of Varroa trap on the bottom board. The trap is screened to prevent the bees
from carrying off dead mites. The paper lining the trap is also greased so
that live mites stick after falling on the surface. Italian beekeepers have
also worked into their management procedures routine checks of brood and
adults for parasitization.
Cultural controls in Italy which show success should be experimented with in
Florida. Of particular interest is periodic removal of parasitized sealed
drone brood. A specific scheme developed in the Torino area provides a colony
with a frame of drone comb foundation. A third of this comb with sealed
larvae/pupae is then removed every eight days.
Unfortunately, in both Italy and Florida, a necessary key ingredient to
an effective integrated pest management program against Varroa is missing.
The economic threshold level, below which it is not recommended nor
uneconomical to resort to chemical control, is unknown. It now is apparent
that such a level will only be determined after many years experience
monitoring mite populations in bee colonies by both researchers and
beekeepers in specific geographic regions. In the long run, however,
determining threshold levels is indispensable before either Florida or Italy
will be able to develop satisfactory long-range Varroa control programs.
ROTHENBUHLER BEE LABORATORY AT THE OHIO STATE UNIVERSITY
The new bee laboratory at The Ohio State University has been open for some
time now, but has not had a name. According to a recent article in the campus
newspaper, from now on the building will be called the Walter C. Rothenbuhler
Honey Bee Research Laboratory. The university trustees have approved this to
honor the professor emeritus who pioneered work in honey bee genetics during
his 21 years as a faculty member at that institution.
Many APIS readers have heard Dr. Rothenbuhler speak at bee meetings or read
his papers published in the bee journals. I know they believe, as I do, that
this action is more than justified. I can think of no finer gesture to honor
Dr. Rothenbuhler, who continues to work even in retirement to make the Ohio
State University apiculture program one of the best in the nation.
Malcolm T. Sanford
202 Newell Hall
University of Florida
Gainesville, FL 32611-0312
Phone (904) 392-1801
BITNET Address: MTS@IFASGNV
INTERNET Address: [log in to unmask]
DIALCOM Address: AGS559