Annotation
The
continuing growth of losses of bee colonies from factors that are based on the
infection of bee colonies with Varroa mites forces us to look for new or
well-forgotten old methods of dealing with them. But no fight is possible if
you don't know your opponent well. In the course of theoretical research and
practical experiments for over four years, we managed to understand the peculiarities
of development of Varroa mites population in honey bee colonies, to create a
method for controlling the development of the mite population and to outline
additional ways to combat this parasite which destroy a huge number of bees
around the world. For monitoring of the development of Varroa mites population
we developed our own method on the basis of counting of Varroa mites falling
free of on a sticky board. This method
is based on the monitoring of two different types of falling mites - old
females and young female mites that did not take part in the reproduction. This
made it possible not only to understand the main cycles of reproduction of Varroa
mites in bee colonies, but also to propose simple and absolutely harmless
zootechnical methods for suppressing their development, such as cold wintering,
suppression of the swarming state, removal of the earliest and latest sealed
brood of worker bees. And all this with a precise understanding of those key
points when each of these impacts will be most effective.
Key
words
Varroa
mites, varroatosis, bee diseases
Introduction
Studying
the materials published in the American Bee Journal # 4 2020, we came across
statistics, which fully correspond to our own results obtained during the work
on the Apivox Varroa Eliminator project. This both pleased and upset us, since
the loss of bees wherever they occur, worsens the situation with the bees on
the entire Earth.
In
addition, the statistics again confirmed, that none of the drugs currently used
in beekeeping, no matter how loudly they are advertised, do not radically solve
the problem of combating varroatosis in our apiaries, but only put us "on
the needle" of companies that produce heaps of "highly effective
drugs" for the treatment of bees from various diseases!
Let's move
on to specific data and their interpretation ...
So, the first material is data on the loss of
bees over the past 10 years according to Bee Informed organization (Fig1).
The graph
shows, that in the US, average bee losses have increased
from 25-30 %% to 35-40% per year. Professional beekeepers always say that these
are exaggerated figures that have nothing to do with reality. But, this is not
entirely true.
The graph
shows, that in the US, average bee losses have increased
from 25-30 %% to 35-40% per year. Professional beekeepers always say that these
are exaggerated figures that have nothing to do with reality. But, this is not
entirely true.
Professionals also have bee losses, but they are
significantly less than those of amateurs and beekeepers with small apiaries
(Fig2, Fig3). We also agree with this. The reason, as a rule, is that amateurs
are trying to conduct eco-friendly beekeeping and to use as little as possible
chemicals intended to treat bees from various diseases. At a minimum, they use
them in the event of illness of their bees.
Professional
beekeepers are always trying to act ahead of the curve, as are poultry and livestock
breeders. Why wait for the animals to get sick? This always results in waste of
time and money. All measures for the treatment or, more precisely, for the
prevention of diseases are carried out within clearly defined terms, regardless
of the presence or absence of a real disease. Therefore, diseases occur less
frequently and the losses from them are less. If the main task of the apiary is
pollination or rearing queens, then the amount of chemicals in the combs and
honey does not matter at all for them.
But, as it
can be seen from the graphs, the losses of bees both in professional beekeepers
and in other beekeepers, have been growing in recent years proportionally
despite some difference in absolute values !!!!
In addition
to these data, there is a table, which became the result of a survey of
beekeepers about the reasons for the death of bees in their apiaries. The
result was expected - most of the bees died from infestation with the Varroa
mites! I think that the column "weak in fall" can be safely summed up
with the column "died from the Varroa mites" ... Our studies, which
we told you about, claim, that this is most likely the result of an autumn peak
in the development of the population of Varroa mites, which many beekeepers do
not notice during and after Main honey harvest. So, we believe that 69% of the
deaths of the bees in small apiaries occurs from infestation with Varroa mites,
which today cannot be completely destroyed by any means! What does all this say... It says that despite
the advertising-oriented results of "successful use" of various oils
and chemicals, they are not very effective in real life! To quote from an American
Bee Journal article ... " Four
chemical control options show the greatest potential for better survival in
survey results for the past four seasons. Essential oils Apiguard and
ApiLifeVar show about a 30% greater survival, and use of Apivar about a 29%
better survival. Oxalic acid vaporization demonstrated an 11% better survival
over the past three years, but survival improvement of Oxalic acid drizzle was
minor and in only one of the last three seasons…" But, if we look at Fig. 1, we will see that
there is absence not only of increase in survival, but, on the contrary, from
year to year there is an increase in the death of bees.
That is why
we believe that it is important to understand the vital processes in Varroa
mites going on in bee colonies, to be able to control them and be able to
suppress this development not only with chemical preparations, but also with
simple zootechnical means that you need to know and be able to apply. Ideally,
we believe that it is necessary to achieve such coexistence of bees and Varroa
mites, in which their presence in bee colonies will cease to be lethal for the
latter.
Materials
and methods
There are several methods for obtaining data on
the infestation of a colony of bees, of which the most radical is an alcohol
wash, and the most gentle is the control of the mites drop on a sticky board.
There were a lot of attempts in order to adapt a mites drop for analyzing the
degree of infestation of bee colonies, but everyone wanted to get specific
numerical data, even if this required adjusting the numbers to the result. On
the basis of this method, there were built some methods which were distributed
by the ministries of agriculture of the USA, Britain, Spain and other countries (Fig. 5).
Based on
the average number of mites falling on sticky board per day, it is proposed to
build a method for treating bees with acaricidal preparations. Representatives
of the agricultural industry, trusting scientists, recommend this method for
assessing the infestation of bee colonies as the least laborious. It is
believed that it gives fairly accurate results. But sometimes it's not quite
like that, and sometimes it's not like that at all. In various scientific works
of scientists who studied and evaluated the accuracy of all known methods for
calculating infestation, it is written that all methods are equally inaccurate
at the very beginning , when the number of mites in the family is small, and at
the end of the season, and that in these works scientists use at least three
different coefficients for converting the number of daily falling mites to the
total number of mites exists in the bee colony. We know that there is a
coefficient by which the average daily tick talus is multiplied equal to:
1) 20 in spring, and to 40
in summer and to 250-500 during broodless season.
Fig.6 ( Population model for the ectoparasitic mite Varroa
jacobsoni in honey bee (Apis mellifera) colonies Stephen Martin National Bee Unit, Central Science
Laboratory, Sand Hutton, York, YO4 1LZ, UK )
2)
120 throughout the season. Fig.7 (Development of the mite, Varroa jacobsoni
oud., in the honeybee, Apis mellifera L., in Michigan, USA, and a comparison of
diagnostic methods for detection of the mites Ahmad Al Ghamdi and Roger
Hoopingarner )
3) 170-200 throughout the season. Fig.8 (GUÍA TÉCNICA PARA
PARA LA LUCHA Y CONTROL DE LA VARROOSIS Y USO RESPONSABLE DE MEDICAMENTOS
VETERINARIOS CONTRA LA VARROA DIRECCIÓN
GENERAL DE SANIDAD DE LA PRODUCCIÓN AGRARIA
SUBDIRECCIÓN GENERAL DE SANIDAD E HIGIENE ANIMAL Y TRAZABILIDAD)
This
already suggests that each researcher adjusted the coefficient to the situation
in his apiary, or in his zone. And even
this fitting does not work if used in
mathematical models, which are compared then, with the real results of counting
of Varroa mites in bees... Fig.9 (Population growth of Varroa destructor
(Acari: Varroidae) in honey bee colonies is affected by the number of foragers
with mites Gloria DeGrandi-Hoffman
Fabiana Ahumada Victor Zazueta Mona Chambers Geoffrey Hidalgo Emily Watkins deJong)
For our
project we invented our own method of calculating mites drop. It consists in a
separate count of dark - old, already participated in reproduction females, and
pale-colored young female mites and deutonymphs, which died or were not
fertilized by a male mite inside the cells, and were thrown out by the bees. Fig.10. We call this the two-graph method. So, what
is its meaning ...
The point
is that in addition to the fall of old dark mites, that is clearly visible to
everyone, there is another process - the process of death of young females that
have not yet participated in the growth of the mite's population. Pay attention
to the photo Fig.10. It shows the mites, which fell down on sticky board of our
experimental hive in different seasons of the year. They all have a different
color !!! Mature old fertilized females
are deep red and burgundy! Young females have a bright red color that is darker
or lighter depending on maturity, and the paler ones are not mature females and
transparent individuals are deutonymphs ...
So, the
method of two graphs that we use involves separate accounting of old female
mites - the blue graph, dying during or after breeding, and young females that
did not participate in reproduction - the red graph. By shifting back the blue
graph of the fall of mature dark mites by 2.5-3 months, or the approximate life
span of the mites, we can talk about the approximate time of their birth, and
we can analyze the events that led to their appearance in the bee colony. The appearance
of fall of pale mites, according to our long-term observations, is a very bad
sign, and indicates an over-intensive reproduction of Varroa mites, when it
uses for reproduction all the brood zones that are not even very suitable for
reproduction in terms of climatic parameters. Thus, using two graphs (Fig. 11),
we can learn about the past of the mites population from the blue graph, about
the prospects for its increase in the future, and about the intensity of its
growth process at the moment according to the red graph.
In general,
the mites drop by itself at the time of control is not always indicative. There
are intervals, as we can see from the graphs, when there is practically no fall
of the mites or it is very small. This does not mean that there are no mites or
that its number is small. It's just that the mites are waiting for the right
conditions for mass reproduction, or they're just all young and healthy. From
the graphs, we see that the mass death of Varroa mites of all ages is directly
related to the cycles of enhanced reproduction, which, apparently, takes away
the last strength from old individuals and leads them to death in the cells. In
this case, the idea that the mites live for about 2-3 months and the method of
shifting the schedule of mites drop for 2-3 months back shows the time of their
birth, allowing you to see the real time of birth of this mass of falling
mites. And these are the months when the most active reproduction of bees takes
place, and when it seemed to us that there were almost no mites in the family
(Fig. 11).
Analysis
of graphs of mites drop obtained by us for 4 years of continuous observations
of six families of bees showed that by studying of free fall of Varroa mites on
a sticky board, one can observe the development of the mites population and make
predictions about its changes. But, it must be taken into account that the drop
of mature mites informs us about what happened in the bee family 2-3 months
ago, and makes it possible, although not quite easy, to predict the number of
mites at the moment and in the future. This is possible because we know that in
average the mites population doubles in a month. The appearance of a drop of
pale-colored young mites tells us about a sharp increase in growth of Varroa
mites population and an emergency situation in the bee colony. Observing this
process can allow beekeepers to urgently take the necessary measures to protect
the bees from death.
Results
1)
Observations show on the example of all families, that each next burst of the
mite's reproduction is at least 2-3 times stronger than the previous one. This
difference roughly corresponds to the amount of mature mites fallen free during
the present reproductive cycle, divided by the amount of fallen free immature
mites of the previous reproductive cycle... The value is approximate, but it is
confirmed in all experimental families. You can see it on the graph.
2)
Observations show that swarming state of bees should be avoided by all means.
It is the massive laying of drone and bee brood before swarming and, most
importantly, its thorough heating by the bees, that leads to a catastrophic
increase in the mite's population due to a multiple increase in the
reproductive territory, comfortable for it.
3)
Observations show that if, during the next cycle of enhanced reproduction, free
fall of an immature mites significantly exceeds free fall of an old mature dark
mites, and has sufficiently large values, then this is a very alarming signal.
It can be assumed, that not only a large number of young mites were released,
but the founding females did not die ! Thanks to this, it accumulates the mass
of live mites, ready to participate in the new reproductive cycle, and exactly
this makes the next flash of reproduction so powerful.
During
the main honey flow period, when the mites have less bee's brood in the nest
for reproduction and in the mites population, remains only young viable
individuals, mostly not yet ready to die and fall down on sticky board, free
fall of the mites sharply reduces or stops altogether ... With a decrease in
the flow of honey at the end of the main honey harvest, as well as with removal
of honey by beekeepers at the end of summer, the volume of free space for
laying eggs by the queen increases ... The weather conditions at this time, in
August-September, are still favorable for the bee's brood rearing and for the mite's reproduction. At this
time, beekeepers are trying to get as many young bees as possible, because
exactly these bees will winter and form a family next year. Under these
conditions, starts new powerful laying of brood by the mites, which leads to
the powerful autumn splash in the growth of Varroa mites population. This process is accompanied by a strong fall
of both - old mites born in spring , and immature young underdeveloped individuals
that die in the process of reproduction.
4)
Observations show that the state of a bee colony when a quantity of falling
mature mites reaches quantity up to 5 mites per day, in principle, is not too
bad for a colony of bees of almost any strength. The bees of a strong family
can even withstand a situation, when a quantity of falling mature mites reaches
60-70 mites per day, for up to a month.
They are also can withstand a situation when a quantity of falling
mature mites reaches from 20 to 40 ticks per day, for 2-3 months. Of course, in
the bee's family appear many damaged bees that are unable to fly, and this
weakens the family and reduces its honey productivity... We can see such a
situation in the graphs of three families of our experimental apiary - 5-1,
5-2, 8-1. At the same time, 8-1 and 5-1 produced about 40 kilograms of marketable honey, and a 5-2
family - 60 kilograms, while being in a
stationary apiary. Thus, we can say that the state of a bee colony when a
quantity of falling mature mites reaches quantity up to 10 mites per day, in
principle, is not terrible in the short term for a strong colony of bees. The
danger appears when, in addition to mature dark-colored mites, immature
pale-colored mites appear on sticky board. This is a signal of alarm. This is a
sign of an incipient reproductive "outbreak" of the mites. So, as you
can imagine, the main task of beekeepers is to combat these periodic
reproductive outbreaks! Their suppression should be the main task.
Discussion
So,
thanks to our method of two graphs and based on the results of the control of
the mites drop in 6 families for 4 years, we can state that in the life of
Varroa mites there are three main peaks of reproduction activity with intervals
of greater or lesser decline in reproductive activity between them (Fig. 12 ).
The
first peak - is the winter breeding peak. The time of this peak is January,
February and March. It is at this time that mountain breeds of bees such as
Carnica bees and Caucasian Grey Mountain bees are gradually
beginning the process of rearing of this-year's brood. Depending on the
strength of the bee colony and the weather conditions, this peak can be large
or hardly noticeable ... But as a rule, it is always there. Exactly this peak
helps Varroa mites to overwinter and to rear the first young generations, which
will give a start to the next, most powerful peak in their reproduction - to
the spring pre-honey harvest peak.
The
death of the mites of this breeding cycle occurs in March, April, May, and is
also accompanied by the death of old females, which wintered together with the
bees, and gave life to this generation of the mites. When the winter
reproductive peak is insignificant, free
fall of old hibernated female mites is the main part of the mites drop and it
tends to stop around mid-May, which can create the illusion that the bee colony
is mites-free, if you decision will be based on the size of the mites drop.
The
second peak of reproductive activity falls on pre-swarming time - that is,
mainly on April, May and June. Undoubtedly, the basis of the danger of this
peak is laid precisely in April, when the first mass brood of bees appears and
the mites born during the winter peak, and the mites still remaining after
wintering, can enter the brood en masse for reproduction. Subsequently, the
conditions in a colony of bees preparing for swarming allow the mites to
maximize their population in May and June.
The
death of the mites of this breeding cycle and their fall on sticky board occurs
in the second half of July, August and September. It was at this time that
scientists and beekeepers registered the maximal fall of Varroa mites on a
sticky board and based on this, talked about the mites population growth ...
But this is not entirely true ... It's just that the massive death and fall of
the mites of spring breeding cycle coincides with the third reproductive cycle
of Varroa mites reproduction - post-honey harvest peak! Thus, the mites drop tells us about the both
- about the death of old mites and about the birth of new ones. We will tell
you how this happens a bit later.
The
third peak of reproductive activity of Varroa mites falls on the time after
honey harvest, when the number of bee brood available for reproduction
increases again. In the interval between the second and third peaks, occurs a
period of latent reproduction of the mites. The reason for this is the youth of
most mites and the absence of a large number of old females for which it is
time to die and to fall down on sticky board. At this time, it may also seem
that there are almost no mites in the bee colony. This makes the British and
American Beekeepers' Association's recommendations for mite control on the
basis of counting the number of Varroa mites that fall on a sticky board per
day, meaningless. Exactly at this time the mites drop is minimal for natural
reasons, and does not say anything about the total number of mites in the bee
colony.
The
death and fall on sticky board of the mites born during this peak, as well as
those born in the fall, occurs more or less evenly and usually continues
throughout the winter and spring. As we said, the mites born in late summer and
autumn can survive until the first half of May.
Speaking
about the peaks of reproductive activity, one must not forget that between them
the mites also reproduce more or less actively and the peaks appear against the
fond of some background values. Naturally, such background values are also
present in the mites drop.
Understanding
the main peaks in the development of Varroa mites population leads us to the
understanding that in order to radically reduce the infestation of bee
colonies, it is necessary first of all to suppress these peaks in the
development of the mites, and especially the winter and spring ones.
So,
having come to an understanding of the construction of the life cycle of Varroa
mites, it can be argued that the application of a set of rules for keeping bees
during the year, which allow reducing colony infestation in a natural way, will
provide significant assistance in solving the problem of preserving bees and
suppressing the development of Varroa mites in their colonies. What methods can
be used for this instead of those, or in addition to those that beekeepers
usually use...
Let's consider these methods in chronological order in accordance with
the life of bees ...
Wintering:
The first step in keeping bees properly in terms of Varroa mites control
- is cold wintering.
There
is one very interesting result, as it were, hidden in the diagram obtained by
Bee Informed and related to our previous statement about the death of bee
colonies in small apiaries from varroatosis, even when beekeepers do not notice
it. Pay attention to the diagram Fig.13!
What do the two seasons 2014-15 and 2019-20 have in common? In common they have the fact that in both
cases more bees died in summer than in winter! These years have been extremely
warm and with extremely warm winters. With temperatures 5-6 degrees on average
above the climatic norm!
What
does this mean? It means, that in winter the mites were able to freely breed
several new generations in the winter brood of bees, and to increase its
population 4-8 times compared to normal years when winters were cold, using
February and March and possibly January for breeding!
It
is this possibility that should be eliminated. It is this event that will help to lay the
foundation for the fight against Varroa mites during beekeeping season. Exactly
cold wintering should prevent rearing of winter brood, which is not able to
significantly improve the state of bee family,
but is able to become a "farm" for growing Varroa mites.
Finally, exactly this event will help to avoid the first spring peak in the
growth of the mite's population.
Spring
development till the main honey flow: The
main methods of influencing the mites population in this period are: the reduction of the space suitable for the
reproduction of the mites and the deterioration of the conditions required for
their reproduction. Several techniques can be involved here together or separately ...
1) Creation
and maintenance of young families. Creating young families in the
apiary to replace old working families by forming artificial swarms, by forming
offshoots with mature queen cells, the beekeeper "kills two birds with one
stone at once." Firstly - when
creating such families, the brood which at this time is the main repository of
the mites, is not used or is used minimally. Secondly - such colonies are easy to process in any way,
including using of organic acids, which is a method, that minimally contaminates
frames and honey. Thirdly - the families will have young queens, which is an
excellent anti-swarming technique. Such families, as a rule, have a good start
in development and begin wintering healthy and clean.
2) Suppression
of swarming state of the bees in order to deprive the mites possibility
of super-active reproduction in a huge amount of well-heated brood of worker
bees and drones. Before the start of the main honey collection, possible
methods are: the presence of young
queens, expansion of the nest, removal of maximum possible amount of drone
brood. Firstly, as we have already said, colonies with young queens are, in
principle, much less prone to swarming. Secondly, the expansion of the nest
reduces swarming mood of worker bees and deprives mites of a large, well-heated
brood zone and, most importantly, a well-heated drone brood. Thirdly, the use
of building frames allows not only to reduce swarming mood of the bees, but
also to remove from the hive and destroy almost ninety percent of drone brood with mites in it, with a minimum
expenditure of efforts and without injuring the bee family.
3) Removal
of sealed brood. Removal of frames with sealed brood, which can be
carried out during the period of spring growth of bee's families in order to
prevent swarming and to create offshoots, significantly contributes to the
fact, that the disease does not take on a threatening character in the main
colonies until autumn, even in the absence of other mites control measures. In
addition, holding such an event in June can, under certain conditions, increase
honey productivity of bee's families by reducing number of bees engaged in
brood rearing. At the same time, the families from which the brood was removed,
can be treated with organic acids, and this treatment will be very effective at
this stage.
In the
process of honey collection, it is possible to influence the mites population using method of
of limiting oviposition of the queen. The use of this method will
radically reduce the number of mites in the bee colony, by reducing the
opportunities for their reproduction.
4) Autumn
preparation of bee families for wintering. It is possible that you can
again use the method of removing the sealed brood, and then proceed to
cooling the nest, in order to stimulate the end of brood rearing season.
The autumn removal of last sealed brood
will be useful if in the summer, after honey collection, it was not possible to
do this due to the large amount of brood in the bee colony. After the young
bees will come out of brood cells in the family in which all sealed brood was collected, they can be treated with natural acids
against the mites, and after this, the bees can be returned to their families
using one of the methods of conjunction of the bees. This will allow both to
clear the colonies from the mites, and to preserve their strength for
wintering. At the same time, cooling the nest in the fall will help stop brood
rearing, which is an incubator for the mites.
Conclusion
A
study of scientific articles and printed materials, as well as our own
researches, have shown that using only chemicals, it is impossible to defeat
Varroa mites. When the effectiveness of acaricidal preparations is less than
100%, surviving mites constantly remain, and the overall resistance of Varroa
mites to acaricidal preparations is constantly increasing. Today, it is already
recommended to use 2-3 acaricidal preparations simultaneously or in turn to
treat bees. Nevertheless, the results are deplorable. The rapid development of
apiaries producing queens, and most importantly, bee packages, and massive
selling them to beekeepers in spring, speaks of the constant death of bees in huge
quantities.
It
is not possible to continuously increase the chemical load on the bees, getting
worse results from year to year. It is time to draw attention of beekeepers,
and first of all, beekeepers who have relatively few bee colonies, to
zootechnical methods of combating Varroa mites. All the rules listed here are not
a serious burden for such beekeepers. Some of them have been carried out
before, but some rules do not seem natural and you need to get used to them and
try them out in practice. Then they, like any new business, after a while will
also become natural and familiar, and most importantly, they will increase the
effectiveness of the fight against Varroa mites.
Literature
We
used diagrams and a picture from the works :
1.
Population model for the ectoparasitic mite
Varroa jacobsoni in honey bee (Apis mellifera) colonies Stephen Martin National Bee Unit, Central Science
Laboratory, Sand Hutton, York, YO4 1LZ, UK
2.
Development of the mite, Varroa jacobsoni oud.,
in the honeybee, Apis mellifera L., in Michigan, USA, and a comparison of
diagnostic methods for detection of the mites Ahmad Al Ghamdi and Roger
Hoopingarner
3.
GUÍA TÉCNICA PARA PARA LA LUCHA Y
CONTROL DE LA VARROOSIS Y USO RESPONSABLE DE MEDICAMENTOS VETERINARIOS CONTRA
LA VARROA DIRECCIÓN GENERAL DE SANIDAD
DE LA PRODUCCIÓN AGRARIA SUBDIRECCIÓN
GENERAL DE SANIDAD E HIGIENE ANIMAL Y TRAZABILIDAD
4.
Population growth of Varroa destructor (Acari:
Varroidae) in honey bee colonies is affected by the number of foragers with
mites Gloria DeGrandi-Hoffman Fabiana
Ahumada Victor Zazueta Mona Chambers
Geoffrey Hidalgo Emily Watkins deJong
5.
A deadly honey bee parasite, the Varroa
mite. PUBLISHED BY Bayer AG
