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Varroa Treatment Methods

This page has been archived. It is retained for historical purposes and should not be relied upon for information

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.

The Czech Research Institute have produced a range of treatments that can be applied or have better effectiveness at various times of the year. The Czech program started in 1978 and I have been following it closely since about 1982.

The Czech Institute was founded in 1919 and has been at Dol, 20 km north of Prague, since 1922. In 1997 the Institute was privatised, research continues and they have support from the Czech government and various EU governments. They cooperate and are associated with the Czech Beekeepers union, Czech state veterinary administration and the Austrian professional beekeepers association. Their testing laboratory has accreditation to ISO EN 45001. The diagram below was inspired by one of their publications and represents varroa treatment possibilities throughout the year, including some that were not in the original Czech schedule.

varroa treatment possibilities throughout the year

'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).

'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 organic acids are a 'soft' treatment, they are extremely corrosive and need care and protective clothing when used.

'Physical' or Bio technical Methods

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 then 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).

Pheromone 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
Not a treatment method as such, but their use allows any varroa mites that do fall off the bees to fall right through the mesh onto the ground below. They can be used all year round and can have a sampling board inserted when counts of mite fall need to be ascertained. They should be closed off when using formic acid evaporation or Apiguard.

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.

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.

I asked Vladimir Vesely about a rumour that I had heard, about painting brood with an amitraz emulsion. He replied...

painting with amitraz could not be recommended from the hygienic point of view (dosing is too high in comparison with fumigation). Painting with formic acid in our experiments proved low effectiveness. In formic acid are active its vapours. The amount of formic acid by painting is too small for making optimal concentration of vapours in air. But we have experimented with relatively small areas of brood. The results with larger areas may be better.

Best regards, Vesely, BRI Dol

In a previous Email asking about the details of brood Painting. He replied...

Painting of brood is a method of treatment of bee colonies in early spring when the area of capped brood is very small (less than 10 sq dm). Cappings of the brood are penetrated with water emulsion of fluvalinate ( 125 mg in 50 ml water). Penetration is made by painting with small paintbrush or a cotton wool roll. Only cappings are painted. Consumption of emulsion is very small, no more than 3 mg of fluvalinate are carried out into the colony. Fluvalinate penetrated in cappings acts against varroa mite and his developing stages into the brood cell as well as against varroa females on bees walking on the surface of capped brood. Cappings (carriers of fluvalinate) together with rests of fluvalinate are removed by bees. Risk of residues is negligible.

Best regards, V. Veselý
Bee Res.Inst. Dol
252 66 Libcice n. Vlt,
Czech Republic


Page created summer 2001

Page archived 05/11/2020

 Written... Summer 2001, Revised... 22 November 2001, Revised... 19 & 24 February 2002, Revised... 18 October 2002, Upgraded... 22 May 2006, Further Upgraded... 29 August 2006,
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