ArticlePDF Available

The removal of capped drone brood: An effective means of reducing the infestation of varroa in honey bee colonies


Abstract and Figures

117 Why does removal of drone brood influence varroa populations? The preference of the parasite Varroa destructor for the drone larvae in Apis mellif-era rather than worker larvae, has already been described in 1977 by Grobov 7 and in 1980 by Ritter. 15 This preference (ratio of varroa in drone cells versus varroa in work-er cells) is calculated to be 8.6 by Schulz, 20 8.3 by Fuchs 6 and 6 by Rosenkranz. 16 Ruttner and his colleagues 18 proposed in 1980 to use this preference of varroa for cells occupied by drone brood as a vehicle for their own end. Other writers have shown that in their respective locations par-tial removal of drone brood allowed them to significantly reduce the population of par-asites in colonies. Purposes of the trial The trial presented in this paper had two objectives: ● To evaluate under central European con-ditions the impact of removal of drone brood on populations of varroa. ● To determine whether removal of drone brood is valuable in a control scheme based on autumn treatment with formic acid. Some acaricides used as alternative controls against Varroa destructor, for example formic acid or essential oils, are not always sufficiently effective. We propose as complimentary measures the removal of drone brood or the division of young colonies in spring. These interventions serve to retard the development of varroa populations, and thus reduce the pressure of infestation. They have the advantage of being able to be carried out at the height of the beekeeping season when recourse to chemotherapy would present serious risks of contamination of the honey harvest.
Content may be subject to copyright.
Original Article 117
Why does removal of
drone brood influence
varroa populations?
The preference of the parasite Varroa
destructor for the drone larvae in Apis mellif-
era rather than worker larvae, has already
been described in 1977 by Grobov7and in
1980 by Ritter.15This preference (ratio of
varroa in drone cells versus varroa in work-
er cells) is calculated to be 8.6 by Schulz,20
8.3 by Fuchs6and 6 by Rosenkranz.16
Ruttner and his colleagues18proposed in
1980 to use this preference of varroa for
cells occupied by drone brood as a vehicle
for their own end. Other writers have
shown that in their respective locations par-
tial removal of drone brood allowed them
to significantly reduce the population of par-
asites in colonies.21,14,17,5 11,16
Purposes of the trial
The trial presented in this paper had two
To e valuate under central European con-
ditions the impact of removal of drone
brood on populations of varroa.
To determine whether removal of drone
brood is valuable in a control scheme
based on autumn treatment with formic
Design of the
This trial was carried out in a production
apiary of about 20 colonies of A. mellifera
established in Dadant Blatt hives. Formic
acid was the only acaricide previously used
in this apiary located near Berne, Switzer-
land. All hives were equipped with a mesh-
Bee World 84(3): 117–124 (2003) © IBRA
The removal of capped drone
brood: an effective means of
reducing the infestation of
varroa in honey bee colonies
Some acaricides used as alternative controls against Varroa
destructor, for example formic acid or essential oils, are not always
sufficiently effective. We propose as complimentary measures the
removal of drone brood or the division of young colonies in spring.
These interventions serve to retard the development of varroa
populations, and thus reduce the pressure of infestation. They have
the advantage of being able to be carried out at the height of the
beekeeping season when recourse to chemotherapy would present
serious risks of contamination of the honey harvest.
FIG. 1. A brood frame from which we have removed the lower part of the comb acts as a drone frame.
The frame is placed in the brood nest so that it is quickly build and laid in.
protected floorboard over the whole bot-
tom of the hive. We divided the hives into
two homogeneous groups on the basis of
the natural fall of varroa in October of the
preceding year, which gives a reliable indica-
tion of the number of overwintering
mites10,12and on the strength of the colonies
in spring.
The drone frame
One frame of brood, from which we had
removed the lower half of the comb,
became the drone frame. One such frame
was introduced to the side of the brood
nest of each hive in the test group at the end
of March. During the whole period of brood
rearing we regularly removed the capped
drone brood from this frame by cutting out
the capped cells, whenever it exceeded a
minimum of 1dm2(fig. 1). Drone brood
around the edges of other frames was not
removed. Normally, the drone combs are
rapidly constructed as the amount of drone
brood built in a nest is governed by negative
feedback from drone comb already con-
structed13and availability of sucrose sources
(e.g. good nectar flow or honey stores in
the hive).
Criteria evaluated
The number of capped drone cells removed
from the colonies was determined, and the
number of varroa in this comb was counted.
All colonies were managed following the
same apicultural practice. The strength of
the colonies was estimated from mid-March
until September using the Liebefeld method8
in order to evaluate any impact of the
removal of drone brood on population
development. Honey production was meas-
ured. During the whole period of the trial
the natural fall of varroa was measured once
a week, giving an indication of the progress
of infestation of the colonies. During August
and September we made two series of three
short-term treatments with formic acid,
then we checked the efficiency of these
treatments by the natural fall in October.9
The trial was carried out in 1993, and
repeated in 1994.
Effect on varroa
populations in 1993
The year 1993 was marked by an early
spring and a good nectar flow which
23.03. 12.04. 02.05. 22.05. 11.06. 01.07. 21.07.
Natural drop Varroa/day
1993 Without removal n=10
With removal n=8
1994 Without removal n=9
With removal n=9 9
FIG. 2. Effect of the removal of drone brood on the natural drop fall of varroa in 1993 and 1994 (average).
encouraged the raising of drones, and thus
permitted the frequent removal of capped
drone cells. It was thus possible to take an
average of 4.1cuttings of drone brood per
colony (minimum 1, maximum 6) between
15 April and 15 July.
We removed an average of 3374 capped
drone cells per colony carrying 788 varroa
(table 1). For these two figures there are
important variations per hive.
The average natural falls of the test and con-
trol groups (fig. 2) differed progressively
from the month of May. While the fall of
mites remained low in the hives where we
had cut out drone brood, it rose very rap-
idly in the hives without removal. This
increase is an indication that the progress of
varroa populations is to a large extent
retarded by the elimination of mites found
in the drone brood.
The formic acid treatments in August and
September confirmed the effect of the
biotechnical measures: the populations of
mites in the test hives at the end of the sea-
son were 3.5 times less than in the control
hives. In this latter group five hives out of
eight showed an infestation greater than
5000 mites with a maximum of 12 928. Bees
with deformed wings were seen in some of
the control hives because of the excessive
load of parasites.
Effects on the bees in
The honey harvest and colony development
were not significantly affected by the
removal of cells of drone brood (fig. 3).
Also, there was no significant difference
between the two groups in the total quan-
tities of worker brood raised during the
year: test, 140 551±22 675 cells; control,
142 852 ± 16 853 cells (average ± s.d.).
Effects on varroa
populations in 1994
The spring of 1994 was cold and rainy, char-
acterized also by a weak nectar flow, which
TABLE 1. Results of th
Year Number of cuts Drone cells removed
with removal mean (n= 10) 4.13374
s.d. 1.4 1681
without removal mean (n= 8) - -
s.d. - -
with removal mean (n= 9) 2.3 3588
s.d. 1.11657
without removal mean (n= 9) - -
s.d. - -
1Natural drop of varroa measured in the week before treatment with formic acid
*The means of the groups with and without removal of drone brood in the same year are statistically different (ttest; P0.05)
permitted an average of only 2.3 cuttings of
drone brood per colony (minimum 1, max-
imum 5) between 3 May and 28 June. We
were able to remove 3588 capped drone
cells per colony with 434 varroa (table 1).
As in 1993 the natural fall of mites in the
control group hives rose rapidly from mid-
May, while the rise in the test hives did not
happen until six weeks later, and in a more
gradual manner (fig. 2).
The controlled treatments with formic acid
showed that in spite of the reduced number
of cuttings, this biotechnical method had
restricted the consequent development of
varroa populations. During the formic acid
treatments we counted more than double
the parasites in the hives without drone
brood removal.
Effects on the bees in
The unfavourable nectar flow in 1994 did
not allow any harvest of honey, and thus
made a comparison between the two
groups impossible. The colony strength and
total number of worker cells raised was not
significantly influenced by the removal of
drone brood.
The removal of drone
brood removes the
pressure of infestation
without hindering the
These results show that under central
Europe conditions the removal of drone
brood is an efficient means of slowing the
development of varroa populations, even
when the number of cuttings is reduced.
Under our climatic conditions, and in the
context of an alternative control pro-
gramme using only short-term formic acid
treatments in autumn, these biotechnical
measures are shown to be indispensable in
preventing colonies from perishing as early
as July. The results are probably the same as
for long-term treatment with formic acid.
he 1993 and 1994 trials.
Varroa in removed Natural drop Mites killed Honey harvest
drone brood before treatment1by treatment (kg)
mites/day with formic acid
788 3.50 15316.6
677 2.18696 3.4
-40.20* 5693* 7.7
-34.49 3853 4.3
434 11.54 2093
352 11.42 1104
-28.02 4437*
-26.27 2948
The removal of drone brood as we have
described is only one measure of a system,
and does not in any case allow the aban-
donment of other treatments, as has been
confirmed by the observations of
Rosenkranz,17,16Schulz,21Marletto11 and
Wilkinson.24 Some authors have suggested
the introduction of uncapped drone brood
into colonies with no other brood with the
aim of trapping the mites.4,19,3,2 This method
is comparatively labour intensive, and even
though an efficiency of up 90% can be
attained, it does not relieve the beekeeper
of using some acaricide treatment.
In our trial the removal of drone brood had
no negative effect on the development of
the colonies and on honey production. See-
ley,22 by providing colonies with added drone
combs, measured a significant reduction of
honey yields in comparison with colonies
without addition. But he concluded that
providing colonies with drone combs might
still be desirable since eliminating mites may
compensate for the negative effect of drone
comb addition on honey yields.
Allen1and Seeley22 claimed that colonies
given a frame of drone comb had less drone
cells on the edges of the other worker
brood frames. An additional advantage is a
significant harvest of wax. The number of
drones in our colonies is sufficient to guar-
antee the fertilisation of queens.
Examination of drone
brood? Not viable for
diagnosing varroosis
Our results showed that it is not possible
to calculate the size of the varroa popula-
tion parasitising a colony simply by examin-
ing the infestation rate of drone brood. This
is probably influenced in part by the cycles
of drone brood production in each colony
and in part by the cyclical nature of the
infestation of cells by varroa. The parasite
load of drone cells was seen to vary from
one- to six- times in the space of a week,
without any relation to the actual varroa
population. This confirms the observations
of Ritter & Ruttner15who also observed the
weakness of the infestation of drone brood
01.03. 01.04. 02.05. 02.06. 03.07. 03.08. 03.09. 04.10.
Number of bees
1993 without removal
with removal
1994 without removal
with removal
FIG. 3. Colony development for the groups with and without drone brood removal in 1993 and 1994
as a measure of colony infestation. Wilkin-
son & Smith,24 on the other hand, concluded
using a theoretical model, that sampling nat-
urally produced drone brood is valuable for
estimating the level of mite infestation in a
Will varroa adapt itself
to this biotechnical
The often expressed fear that removal of
drone brood will select for a population of
varroa that prefer worker brood does not
seem to be justified. We should remember
that the removal of drone brood occurs
only during a short period, and for the rest
of the year the mites are obliged to breed
in worker cells. Even during the drone rais-
ing season there will always be more varroa
in worker cells simply because there is usu-
ally 10-times more worker brood in a nor-
mal productive colony as the area of drone
combs in feral colonies is only around 17%
of the total23.
Implications for
This trial has shown the efficacy of removal
of drone brood in retarding the develop-
ment of varroa populations. This biotechni-
cal control allows the deferral of acaricide
treatments until the end of summer with-
out damaging infestation of the colony. This
method is important for the success of
some strategies of alternative control, as for
example that which relies exclusively on
autumn treatments with formic acid. On its
own however the removal of drone brood
is insufficient to keep the parasite under
Properly planned, the removal of drone
brood can be integrated without much
increase of work into the normal manage-
ment of modern apiaries.
What to do in practice?
Three points to note:
Introduce the drone frame into the
colonies sufficiently early (end of March-
beginning of April).
The drone frame should be introduced
into the brood nest so that it can be
quickly built-up and have eggs laid in it. In
this position the drone brood will also
capture many more parasites16.
Avoid at all cost the emergence of drones
from the drone frame, as this will
increase the varroa population. If the fol-
lowing visit cannot be planned to occur
before the emergence of drones, then
the frame should be removed and
replaced with a full frame of worker cells.
To avoid an increase in work, it is neces-
sary to integrate the removal of drone
comb into the normal apiary manage-
ment for this time of year. Given the
normal growth of colonies, swarm con-
trol, placing and checking of honey boxes,
the removal of drone brood should result
in little increase in work.
Translation by Peter Kerr, Auckland, New Zealand
1.ALLEN, M D (1965) The effect of a plentiful sup-
ply of drone comb on colonies of honeybees.
Journal of Apicultural Research 4(2): 109–119.
Varroabekämpfung mit Drohnenbrutfang-
waben. Bienenvater 121(9): 18–25.
, J J M
(1999) Effective biotechnical control of Varroa
jacobsoni mites: Applying knowledge of brood
cell invasion to trap honey bee parasites in
drone brood. Journal of Apicultural Research
38(1/2): 49–61.
, J H P M;
J J M (1997) Successful trapping of Varroa jacob-
soni with drone brood in broodless Apis mel-
lifera colonies. Apiacta 32(3): 65–71.
5. FRIES, I; HANSEN, H (1993) Biotechnical control
of varroa mites in cold climates. American Bee
Journal 133(6): 435–38.
6. FUCHS, S (1990) Preference for drone brood
cells by Varroa jacobsoni Oud in colonies of Apis
mellifera carnica. Apidologie 21(3): 193–199.
7. GROBOV, O F (1977) Varroasis in bees. Varroasis a
honeybee disease. Apimondia Publishing
House; Bukarest; pp 46–70.
prüfung der Schätzmethode zur Ermittlung
der Brutfläche und der Anzahl Arbeiterinnen
in freifliegenden Bienenvölkern. Apidologie
18(2): 137–146.
Alternative Varroabekämpfung. Schweizerische
Bienen-Zeitung 118(8): 450–459.
10. IMDORF, A; KILCHENMANN V. (1990) Natür-
licher Milbenfall im Oktober. Schweizerische
Bienen-Zeitung 113(9): 505–506.
Further tests on varroa disease control by
means of periodical drone brood removal. Api-
cultura Moderno 82(6): 219–224.
12. MOOSBECKHOFER, R (1991) Varroaverluste
während der Ueberwinterung. Bienenvater
112(9): 300–303.
13. PRATT, S C (1998) Decentralized control of
drone comb construction in honey bee
colonies. Behavioral Ecology and Sociobiology
42(3): 193–205.
Bekämpfung der Varroatose durch Entnahme
der gedeckelten Drohnenbrut. Apidologie
15(3): 245–246.
15. RITTER, W; RUTTNER, F (1980) Diagnosever-
fahren (Varroa). Allgemeine Deutsche Imk-
erzeitung 5:134–138.
16. ROSENKRANZ, P (1998) Drohnenbrutentnahme
zur Varroatose-Kontrolle. Die Bienenpflege (5):
17. ROSENKRANZ, P; ENGELS, W (1985) Konse-
quente Drohnenbrutentnahme, eine wirk-
same biotechnische Massnahme zur Min-
derung von Varroatose-Schäden an
Bienenvölkern. Allgemeine Deutsche Imk-
erzeitung 21(9): 265–271.
Brutstop und Brutentnahme. Allgemeine
Deutsche Imkerzeitung 14(5): 159–160.
(1996) Zur Wirksamkeit von Drohnenbrut-
Fangwaben in brutfreien Bienenvölkern. Api-
dologie 27(4): 293–295.
20. SCHULZ, A (1984) Reproduktion und Population-
sentwicklung der parasitischen Milbe Varroa
jacobsoni Oud. in Abhängigkeit vom Brutzyklus
ihres Wirtes Apis mellifera L. Thesis, Inaugural
Dissertation an der J. W. Goethe-Universitèt
Frankfurt am Main; Frankfurt, Germany.
Drohnenbrut als Varroa-Falle. Die Biene
119(2): 58–60.
22. SEELEY, T D (2002) The effect of drone comb on
a honey bee colony’s production of honey. Api-
dologie 33(1): 75–86.
23. SEELEY, T D; MORSE, R A (1976) The nest of the
honey bee (Apis mellifera L.). Insectes Sociaux
23: 495–512.
24. WILKINSON, D; SMITH, G C (2002) Modelling
the efficiency of sampling and trapping Varroa
destructor in the drone brood of honey bees
(Apis mellifera). American Bee Journal 142(3):
Swiss Bee Research Centre, Dairy Research Station, Liebefeld, CH-3003, Bern,
... Good results can be achieved when 4 to 5 fully capped trap frames are removed per season (Charrière et al., 2003). It is worth noting that DBR is mainly used by small-scale beekeepers in Europe and is considered labour-intensive or not effective enough as a single treatment elsewhere (Evans et al., 2016;Whitehead, 2017). ...
... When done properly, the effectiveness of DBR is demonstrated by the fact that the number of mites during colony development in spring and early summer was significantly lower than in untreated colonies (Wantuch & Tarpy, 2009). Final infestation rates of colonies after late summer treatments were also substantially lower than in colonies where DBR was not performed (Calderone, 2005;Charrière et al., 2003). However, to date, there are few data on how many mites a single drone frame can actually carry. ...
... It is known that drone brood attracts varroa mites on average eight times more than worker brood and is, therefore, an effective means of controlling this pest when removed (Charrière et al., 2003). Due to limited data, it is currently unclear how many mites are removed by a single frame and at what status drone cells were cut. ...
Full-text available
Varroa mites are highly attracted to drone brood of honey bees (Apis mellifera), as it increases their chance of successful reproduction. Therefore, drone brood removal with trap frames is common practice among beekeepers in Europe and part of sustainable varroa control. However, it is considered labour-intensive, and there are doubts about the effectiveness of this measure. At present, it is mostly unknown how many mites a drone frame can carry at different times of the season, and how many mites can be removed on average if this measure is performed frequently. Therefore, we sampled a total of 262 drone frames with varying proportion of capped cells (5–100%) from 18 different apiaries. Mites were washed out from brood collected from mid-April to mid-July based on a standard method to obtain comparable results. We found that a drone frame carried a median of 71.5 mites, and with the removal of four trap frames, about 286 mites can be removed per colony and season. In addition, mite counts were significantly higher in June and July than in April and May (Tukey-HSD, P < 0.05). The number of mites and the proportion of capped cells, however, were not correlated (R2 < 0.01, P < 0.05). Our results suggest that drone brood removal is effective in reducing Varroa destructor numbers in colonies, supporting the findings of previous studies on the efficacy of this measure. Although mite counts varied, we believe that increasing sample size over different seasons and locations could elucidate infestation patterns in drone brood and ultimately improve drone brood removal as an integrated pest management tool for a wider audience of beekeepers.
... Additionally, some beekeepers choose to observe the infestation rates of drone brood as they remove them from the hive (Wilkinson and Smith 2002). While robust sampling of capped cells from a brood frame could be informative as an infestation rate, drone brood production is seasonal (Charriere et al. 2003, Branco et al. 2006. Thus, sampling only drone brood would not be effective for most of the year and this method lacks any kind of standardization. ...
... This method has been shown to be effective at lowering mite levels as much as 50.3-93. 4% (Calis et al. 1999, Wilkinson and Smith 2002, Charriere et al. 2003, Calderone 2005, Wantuch and Tarpy 2009), though it is only useful in the spring and early summer seasons when the colonies actively rear drones (Wantuch and Tarpy 2009). Drawbacks with drone removal include the intensive labor associated with the practice, the required sacrifice of many drones, and the danger of rapid Varroa population growth if one accidentally leaves the drone frames within the hive without killing the mites. ...
... While the mode of action for OA is not fully understood, OA kills Varroa upon contact (Aliano et al. 2006, Aliano andEllis 2008) and is also effective at dislodging mites as it increases honey bee grooming behavior (Schneider et al. 2012). Beekeepers commonly treat their colonies with a ≥3% OA solution by dissolving ~35 g of OA dihydrate (Api-Bioxal) into 1 l of 1:1 sugar: water (weight:volume) solution and trickling 50 ml of the solution between the tops of frames (Charriere andImdorf 2002, reviewed by Rademacher andHarz 2006). Some also choose to spray 3-4 ml of the solution directly onto one side of the frames of bees (reviewed by Rademacher and Harz 2006). ...
Full-text available
Varroa destructor is among the greatest biological threats to western honey bee (Apis mellifera L.) health worldwide. Beekeepers routinely use chemical treatments to control this parasite, though overuse and mismanagement of these treatments have led to widespread resistance in Varroa populations. Integrated Pest Management (IPM) is an ecologically based, sustainable approach to pest management that relies on a combination of control tactics that minimize environmental impacts. Herein, we provide an in-depth review of the components of IPM in a Varroa control context. These include determining economic thresholds for the mite, identification of and monitoring for Varroa, prevention strategies, and risk conscious treatments. Furthermore, we provide a detailed review of cultural, mechanical, biological, and chemical control strategies, both longstanding and emerging, used against Varroa globally. For each control type, we describe all available treatments, their efficacies against Varroa as described in the primary scientific literature, and the obstacles to their adoption. Unfortunately, reliable IPM protocols do not exist for Varroa due to the complex biology of the mite and strong reliance on chemical control by beekeepers. To encourage beekeeper adoption, a successful IPM approach to Varroa control in managed colonies must be an improvement over conventional control methods and include cost-effective treatments that can be employed readily by beekeepers. It is our intention to provide the most thorough review of Varroa control options available, ultimately framing our discussion within the context of IPM. We hope this article is a call-to-arms against the most damaging pest managed honey bee colonies face worldwide.
... After capping, the drone brood must be removed from the colony before the adult drones and mature Varroa hatch. This procedure can be performed several times per season (Charrière et al. 1998(Charrière et al. , 2003. ...
... The procedure is repeated three to four times in a row (Maul et al. 1988). The trapping comb technique is very effective and can reach an efficacy of 95% if it is done correctly with enough worker cells available to the queen Calis et al. 1999;Charrière et al. 2003;Engels et al. 1984). The disadvantages of this method are the possible attenuation of the colony and labor intensiveness (Engels et al. 1984). ...
Full-text available
The beekeeping sector is facing many challenges. One of the greatest is maintaining healthy colonies that produce high-quality products without any residues of veterinary medicines and with low environmental impact. The main enemy is the ectoparasitic mite Varroa destructor, the most significant honeybee pest and a key factor in high colony losses worldwide. In the previous four decades, three pillars of Varroa control have crystallized to be essential for sustainable management: API technical measures, chemical treatments, and resistant stocks of honey bees. In the long term, the latter is probably the most sustainable as it is a step to self-sustaining populations of feral and managed colonies. We recognize the significance of progress in knowledge of all three pillars to conquer Varroa and of their successful usage in accordance with local and global conditions and capabilities. In this review, we present a possible integration of the components of the three pillars of Varroa control strategies in the light of sustainable beekeeping and provide their linkage to the production of high-quality and safe honeybee products and maintaining healthy colonies.
... Harmful substances must not be allowed to enter beekeeping products. One of the most gentle ways to combat the spread of Varroa mites and other diseases is to remove bee drone larvae from the hive (Charriére et al., 2003). Beekeepers on organic farms use this technique to control Varroa mites, because bee drone cells are attracted by a significantly higher number of mites than working bee cells. ...
Conference Paper
Full-text available
The aim of this study was to review research findings and information about chemical composition and application of bee drone brood homogenate for food purposes. As the world’s population grows, global warming and the impact of meat production on the ecosystem are increasingly being discussed. Various non-traditional sources of protein, such as insects and larvae, could replace traditional sources of meat protein in the future. Drone brood homogenate is obtained from honey bee drone larvae and is considered to be a very high value by-product of beekeeping. Scientific studies prove the prophylactic properties of drone brood homogenate to improve fertility and strengthen immunity against viral diseases. This product is rich in nutrients, amino acids, vitamins, minerals and hormones but a certain harvesting and processing technology is required to ensure that the product has a sufficient shelf life and an attractive appearance.
... Cette méthode est répétée 3 fois d'avril à juin pour une meilleure efficacité. Elle permet de réduire l'infestation à court terme (Cahier technique, 2019; Charrière et al., 2003). En effet, les colonies devront être traitées en fin de saison. ...
Background Varroa destructor is a parasite of honeybees. It causes biological damage leading to the colony collapse in the absence of treatment. In recent years, acaricide resistance has emerged in Varroa mites, leading to a decrease in treatment efficacy. We modelled the action of Apivar® (amitraz) treatment, using three input parameters: treatment duration, treatment period, and daily mortality due to the treatment. The output parameters were cumulative mite mortality during treatment, the residual number of Varroa mites, and treatment efficacy, expressed as a percentage. Results The model was validated by monitoring efficacy in the field, in 36 treated hives. According to the model, treatment in the absence of brood is optimal. For a long period without egg laying during the winter, an initial infestation of 100 mites and a start date for treatment of August 7th, a minimal treatment efficacy of 98.8% is required for stabilisation of the mite population for year to year. More effective treatment is associated lower cumulative numbers of dead Varroa mites over the entire treatment period. Thus, the total number of dead mites observed during the monitoring of field efficacy provides information about more than just the initial level of colony infestation. The proportion of resistant mites can be modelized by a decrease of daily mortality rate influencing treatment efficacy. Management of the initial Varroa mite infestation of the colony by the beekeeper can compensate for the decrease in treatment efficacy for resistance thresholds of up to 40% of resistant mites. Conclusion Treatment efficacy depends on several parameters, including initial level of infestation, treatment period and the presence of acaricide resistance. Amitraz resistance may lead to treatment failure, even if the beekeeper is able to keep initial infestation rates low. This article is protected by copyright. All rights reserved.
... So, efforts should be made to reduce the population of drones in the colony when these drones are not required for mating of the gynes, as a drone bee consumes 8-10 times the honey consumed by a worker bee in its daily routine. Partial removal of drone brood in term of the removal of 3-4 completely capped drone combs at the beginning of the season also reduces the fi nal mite population about 50-70 % (Charrière et al. 2003 ). ...
... Sustainable Varroa control is a labor-intensive process requiring a combination of different measures, e.g. monitoring of mite fall, drone brood removal trapping (Calderone, 2005;Charriére et al., 2003), and application of miticides in rotation. Such "integrated pest management" needs to consider the population dynamics of Varroa as well as the honey bee colony so that measures can be applied at appropriate times of the year (Rosenkranz et al., 2010). ...
Explaining the reasons for the high honey bee (Apis mellifera) colony loss rate in recent years has become a top global research priority in apicultural and agricultural sciences. Although there are indications of the role played by beekeeping management practices on honey bee health, very little information is currently available. Our study aimed to characterize the beekeeping management practices carried out in Belgium, and to determine the relationship between beekeeping management practices and colony losses. Variables obtained from face-to-face questioning of a representative randomized and stratified sample of Belgian beekeepers (n = 186) were integrated into a logistic regression model (univariate and multivariate) and correlated to the declared colony loss rates to identify risk and protective indicators. We used a classification tree analysis to validate the results. We present evidence of a relationship between poor beekeeping management practices and colony losses. The main factors protecting honey bee colonies are the aptitude of the beekeeper to change his management practices, the hive type, the equipment origin and hygiene, wintering in proper conditions (the use of divider boards, i.e. board blocks or space fillers off part of the hive body), the colony strength estimation before wintering, winter monitoring, and last but not least, appropriate integrated pest management. Proper estimation of the Varroa infestation level should be performed prior to treatment. The consequences of poor beekeeping practices on honey bee health can be addressed by proper training of beekeepers. An online tool was developed and published for beekeepers allowing them to evaluate the effect of their management practices on colony health.
Full-text available
Bees are the major pollinators in natural ecosystems and in the agricultural production of several crops used for human consumption. However, they are exposed to multiple stressors that are causing a serious decline in their population. We highlight a major one among them, the Varroa destructor mite (Varroa) that causes severe impacts on the health of honey bee colonies, transmitting a variety of viruses that can affect the survival ability of individual bees and entire colonies. Diagnosis and mite control methods have been intensively studied in recent decades, with many studies in different areas of knowledge having been conducted. This overview summarizes these studies with a focus on colony defense systems, biological characteristics of the parasite Varroa, diagnostic methods used to establish the infestation level of colonies, and currently used control methods.
Full-text available
The natural honey bee nest was studied in detail to better understand the honey bee's natural living conditions. To describe the nest site we made external observations on 39 nests in hollow trees. We collected and dissected 21 of these tree nests to describe the nest architecture. No one tree genus strongly predominates among bee trees. Nest cavities are vertically elongate and approximately cylindrical. Most are 30 to 60 liters in volume and at the base of trees. Nest entrances tend to be small, 10 to 40 cm2, and at the nest bottom. Rough bark outside the entrance is often smoothed by the bees. Inside the nest, a thin layer of hardened plant resins (propolis) coats the cavity walls. Combs are fastened to the walls along their tops and sides, but bees leave small passageways along the comb edges. The basic nest organization is honey storage above, brood nest below, and pollen storage in between. Associated with this arrangement are differences in comb structure. Compared to combs used for honey storage, combs of the brood nest are generally darker and more uniform in width and in cell form. Drone comb is located on the brood nest's periphery. Comparisons among Apis nests indicate the advanced characters in Apis mellifera nests arose in response to Apis mellifera's adoption of tree cavities for nest sites.
Full-text available
A computer model simulating varroa mite (Varroa destructor— previously known as Varroa jacobsoni) infestation in colonies of honey bees (Apis mellifera) confirmed that, due to the preference of mites to invade drone (male) honey bee brood to reproduce, a very high pro-portion of the mite reproduction could occur in a relatively small amount of drone brood. Several regimes of sampling or removing drone bee pupae to estimate or remove numbers of varroa mites were simulated to compare their effectiveness. The model indicated that regular sampling of at least 100 drone pupae could provide the bee-keeper with a useful warning of when numbers of varroa were approaching damaging levels. An infestation level of 15% of drone pupae would be a conservative threshold to indicate treatment was imminently required. The model indicated that significant reduction of mite numbers could be achieved either by very regular uncapping and removal of most of the natural drone pupae, or by trapping mites in artificially high numbers of drone pupae. The numbers of drone pupae required to significantly delay the mite build-up could be reduced considerably by trapping at a time when the bee colony was otherwise broodless. However, the varroa numbers were not con-trolled sufficiently by drone brood removal alone in any of the regimes tested.
Full-text available
In colonies of A mellifera carnica infested with Varroa jacobsoni, the invasion of worker brood cells and drone brood cells by reproductive female mites was studied. In 68 choices between brood combs of both cell types, the infestation of mites per cell was, on average, 8.3 times higher in drone brood. This drone cell preference was not affected by the infestation level. It was more marked if drone brood was rare and it decreased towards the end of the drone rearing season.
This study examined the impact on a colony's honey production of providing it with a nat- ural amount (20%) of drone comb. Over 3 summers, for the period mid May to late August, I mea- sured the weight gains of 10 colonies, 5 with drone comb and 5 without it. Colonies with drone comb gained only 25.2 ± 16.0 kg whereas those without drone comb gained 48.8 ± 14.8 kg. Colonies with drone comb also had a higher mean rate of drone flights and a lower incidence of drone comb build- ing. The lower honey yield of colonies with drone comb apparently arises, at least in part, because drone comb fosters drone rearing and the rearing and maintenance of drones is costly. I suggest that providing colonies with drone comb, as part of a program of controlling Varroa destructorwithout pesticides, may still be desirable since killing drone brood to kill mites may largely eliminate the neg- ative effect of drone comb on honey yields. comb foundation / drone / drone comb / honey bee / honey production
Honey bee colonies furnish their nests with two types of comb distinguished by cell size: large cells for rearing males (drone comb) and small cells for rearing workers (worker comb). The bees actively regulate the relative quantity of each type, a behavior likely to be important in setting a colony's sex ratio. Experimental analysis of the information pathways and control mechanisms responsible for this regulation found the following results. The amount of drone comb in a nest is governed by negative feedback from drone comb already constructed. This feedback depends on the workers having direct contact with the drone comb in their nest, but does not depend on the queen's contact with the comb. The comb itself, rather than the brood within it, is sufficient to provide the negative feedback, although the brood may also contribute to the effect. These findings show that drone comb regulation does not depend on the queen acting as a centralized information gatherer and behavioral controller. Instead, the evidence points to a decision-making process distributed across the population of worker bees, a control architecture typical of colony organization in honey bees and other large-colony insect societies.