Numerous types of treatment Have been tried in many
countries of the world. These treatments fall into several categories
which are listed below. The aim is to reduce the varroa population to
a minimum by the time that brood rearing stops and the bees are ready
for winter. Additional treatments may be needed in spring before
supers are required. There is a risk of drone infertility if spring
treatments are required.
'Hard' Chemicals
Usually these are veterinary medicines... With defined treatment
instructions. It is wise to follow these instructions as resistance
to the particular chemicals may be speeded up by using the wrong
dose or honey may be contaminated if the advised timing is altered.
Bayvarol was the first example
to be licenced in UK with Apistan
being the second. The rest of this list is either not licenced in UK,
but is a licenced treatment in some other countries or has
certification that has lapsed.
Taktivar and
Gabon PA 92 are
licenced and used in the Czech Republic.
Cekafix is licenced in Germany. The licence for
Folbex VA has lapsed
(it is not recommended as wax residues build up quickly).
Pherovar is still under
development as of Feb 2001.
'Soft' Chemicals
This category contains Formic Acid,
Oxalic Acid and
Lactic Acid as well as various
Essential Oils.
Thymol Crystals
and ApiGuard also fall into
this category. Although the acids are a 'soft' treatment, they are
extremely corrosive and need care and protective clothing when used.
'Physical' or Bio technical Methods
- Powders
- Flowers of sulphur has been suggested as it is both a fine powder
and has been effective against acarine mites. It can be puffed onto
the bees or dribbled on to seams of bees between frames.
- Icing sugar
- (also known as 'powdered sugar') can be dribbled onto the seams of
bees... There has been some suggestion that this can damage the early
stages of larvae, but I will find out more and update later.
- There may be some mileage in mixing flowers of sulphur and icing
sugar, but test need to be conducted.
- Removal of Nucleus
- By forming a nucleus early in the season, with zero brood, all the
mites will be on the adult bees and vulnerable to fumigation or
aerosol treatment methods. The nuc can be developed to become next
season's production colony. The
Taranov Swarm Method
would be ideal for this purpose.
- Queen/brood isolation
- Various frame traps made of queen excluder material are produced
by the appliance trade.
- In a normal hive, Varroa infested brood is split between 60% drone
and 40% worker brood.
- By caging the queen on an empty drawn comb in a cage made of
queen excluder material the mites can be 'drawn' to this frame as,
after eight days, it will be the only one with open brood. After
nine days this trapped brood is sealed and the frame is 'sacrificed'
and another empty drawn comb placed with the queen in the trap. The
second comb is sacrificed, again after 9 days, and a third frame is
placed in the trap, if this is destroyed as well then we have no
brood of any description left as after 24 days all other cells
(worker or drone) will have emerged. The idea being that this isolated
frame will have a disproportionate number of varroa infesting it and
thus the destruction of it will harm the varroa more than the bees.
It does disrupt brood development, but if it is timed for the back
end of the main honey flow then will not reduce forager numbers and
there is still time for a force of 'winter bees' to be raised. (There
may even be a benefit in causing this to happen later than usual as
the resulting winter bees will be slightly younger and thus have more
life in spring.)
There are many variations to this method... one, two or three
entrapments or one early in the season and one late. One, two or three
combs per trap have been suggested and versions using drone comb or a
mixture of drone/worker comb are also mentioned in literature.
This method is time consuming and messy, but it also provides a "brood
break". One disadvantage of this technique is the cells vacated by
the earliest emerging brood may be clogged with pollen and honey as
they are out of reach of a laying queen.
- Drone brood 'magnet'
- As the mite is preferentially attracted to drone cells they can
be used to trap mites and then if the frames are put in a deep freeze
for 3 days the mites and brood will be killed. The frames can have
the cappings scratched then be exposed to the birds for larvae
removal (a hose pipe can also be used and is especially rapid as the
remains of the pupae literally pop out of the cells).
This and the previous method can be combined (two twelve day
entrapments using drone comb).
- Pheramone traps
- Stephen Pernal in his work with varroa and odours, is using a
simple choice test where mites walk in one of two possible
directions towards one of two odours coming from the different arms
of a 'Y' shaped tube, He has discovered various bee extracts that
attract or repel mites by this method. This may result in a trap that
will lure varroa mites to their death.
- Foundation cellsize
- There is much controversy about this at the moment, but much
testing will take place in 2002 and the following years which should
give more information. I have other reasons to adopt small cells and
if there is some benefit in reduced varroa reproduction in such cells
(as is being suggested by some) then I will happily accept it.
'Integrated Pest Management' 'IPM'
- Open Mesh floors
- The Frakno thymol frame,
the Brooks-Knight frame
and other thymol crystal evaporating frames can be used in conjunction
with frames containing drone foundation.
- Icing sugar
- Is a fine powder and can be eaten by the bees... As it has no
medical effect on adult bees it could be used repeatedly although I
am suspicious that it may block spiracles and/or harm developing
larvae.
'Non Medicinal Curative Substances'
This peculiar term has arisen in the UK to cover non licenced items
in the above lists.
Copper Gluconate is being
marketed as "Happy Hive Salts" which may or may not be effective for
absolute varroa control, but could form part of an IPM strategy.
(there are other uses for this material... more later)
Herbal treatments... Powdered coltsfoot has been used. This
is a powder and works to cause a lack of grip in the varroa mite's
feet just like other powders, but there is said to be some medical
effect as well. This requires more research.
Written... Summer 2001, Revised... 22 November 2001
Revised... 19 & 24 Feb 2002 and 18 October 2002
