# Study on OAV - Superior to dribbling or Spray



## snl (Nov 20, 2009)

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Integrated control of Varroa mites



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Integrated control of Varroa mites
_Varroa_ mites, _Varroa destructor_, evolved in Asia where they are a parasite of the Asian honey bee _Apis cerana_. They have since become a pest of the Western hive bee _Apis mellifera_ and have spread worldwide. Large numbers of _Varroa_ mites can kill a bee colony and the mites can also increase virus mortality. 








Varroa mites on an adult honey bee








A honey bee colony being treated with Oxalic Acid using sublimation method








Oxalic Acid varroa treatment using the dribbling technique








Research facilities manager, Luciano Scandian, counting bees

Controlling _Varroa_ is considered essential for successful beekeeping._Varroa_ was first detected in Britain in 1992. Until recently, _Varroa_ could be controlled using Apistan strips. Apistan contains a chemical (fluvalinate) that is toxic to the mites but is safe for honey bees and humans. Treating a hive with Apistan needed a few minutes work per year and cost just a few pounds.
However, fluvalinate-resistant _Varroa_ now occur throughout much of the world including much of Britain. Alternative methods to kill _Varroa_ have been developed and tested in Europe and North America, especially in countries that never permitted the use of Apistan or where the mites have been resistant for longer. These variously use fumigants (formic acid, thymol), spray the bees in a hive with a solution harmful to _Varroa_ (lactic acid, oxalic acid), trap mites in drone brood that is then removed from the hive and killed, or make use of a mesh hive floor which allows the varroa to fall through and die.
An important strand of our research on pests and diseases concerns the application of oxalic acid (OA). Although OA has been used by beekeepers for several decades to kill varroa, it became clear that a study was needed to determine the effectiveness of different doses and application methods on mite and bee mortality.
An experiement conducted by researchers at LASI using 110 hives comparing three application methods and three different doses was completed in 2014. Hives were treated in early January 2013 when they had no brood. Oxalic acid does not kill varroa in sealed cells, but rather kills those varroa transported on the bodies of workers and also those crawling in cells not yet capped.The researchers determined the proportion of mites killed by washing the mites off a sample of approximately 300 workers bees immediately before and after 10 days of treatment with OA. They also determined the number of bees killed at the time of treatment, together with hive mortality and strength 4 months later in spring.
The results came to a clear and encouraging conclusion. Application of OA via sublimation, where OA is applied in its pure form by vapourising the crystals with a special heated tool, was superior to application as a solution via either spraying or dribbling. Sublimation gave a greater kill of varroa at a lower OA level and showed no increase in bee mortality. In fact, 4 months after treatment, the hives treated via the sublimation had more brood than the 10 untreated colonies.
The sublimation method is quick and easy, as the hives do not need to be opened. To confirm the results obtained by LASI researchers early in 2013, the sublimation technique was retested one year later in December 2013, just before Christmas, in broodless honey bee colonies. An amazing 97% of the varroa were killed by using 2.25g of oxalic acid per hive, and colony survival 3 months later in spring was close to 100%.
This research project was overseen by Prof. Francis Ratnieks and led by PhD student Hasan Altoufailia. LASI facilities manager, Luciano Scandian, assisted with his extensive beekeeping knowledge. The results will be published shortly.
References*Awaiting submission:*
Al Toufailia, H. M., Scandian, L., Ratnieks, F. L. W. The effectiveness of spring drone brood trapping to control Varroa populations in honey bee colonies.
Al Toufailia, H. M., Scandian, L., Ratnieks, F. L. W. Effectiveness of different methods of quantifying Varroa populations in honey bee colonies.
*Submitted:*
Al Toufailia, Scandian, Ratnieks. Comparing different doses and application methods of oxalic acid to control Varroa. Journal of Apicultural Research (accepted).
*Published:*
Al Toufailia, H. M., Amiri, E., Scandian, L., Kryger, P., Ratnieks, F. L. W. 2014. Towards integrated control of varroa: effect of variation in hygienic behaviour among honey bee colonies on mite population increase and deformed wing virus incidence. Journal of Apicultural Research 53: 555-562.
*Popular Journals:*
In British Beekeeper's Association's British Bee Journal
Varroa BBJ 1-15 [PDF 623.42KB]



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## Tenbears (May 15, 2012)

Good stuff, Thanks for posting. But, anyone who has used both methods already knew it. OAV is by far the best we have today!


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## FlowerPlanter (Aug 3, 2011)

Also note there is little room for error when preparing OAD, a small miscalculation could kill a hive. OAD by itself is hard on the bees, increased mortality of the workers, and IMO reduces the longevity of the queen too. OAD can only be done once during the winter because it is so hard on the bees. 

Where as with AOV some have claimed to have doubled the dose and not noticed any bad affects. (With any treatment there may be an increased mortality rate just not as much with AOV)

I am really surprised that anyone still does OAD. As Tenbears implies once you OAV you never go back.


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## Dominic (Jul 12, 2013)

Méthodes alternatives de contrôle des populations de Varroa destructor et d'Acarapis woodi dans les ruches du Québec en minimisant l'utilisation d'insecticides de synthèse (89-2005) 2005



> Lorsque ces deux types de traitements sont combinés avec un traitement à l'acide oxalique en fin d'automne (juste avant l'hivernage et lorsque le couvain est plus rare) l'efficacité peut atteindre 95 %. avec ce niveau d'efficacité les traitements de printemps ne sont plus nécessaires. Et il est fort possible que les traitements d'été ne soient pas nécessaires également. L'apiculteur doit donc viser la réussite des traitement d'automne. Les colonies traitées à l'acide oxalique en fin d'automne combinés avec le Thymovar® ou le MiteAway2® étaient plus faibles à leur sortie de l'hiver lorsque comparées aux colonies témoins traitées avec le pesticide de synthèse (coumaphos: CheckMite®). Cet impact négatif de l'acide oxalique sur le développement des colonies après l'hivernage est plus important avec le traitement à l'acide oxalique par sublimation thermique.


Free translation



> When these two types of treatments are combined with an oxalic acid treatment in the end of Fall (just before overwintering the hives and when brood is rarer), the efficacy can go up to 95%. With that level of efficacy, Spring treatments are no longer necessary. And it is very likely that summer treatments would not be necessary either. The beekeeper must therefore aim in succeeding the Fall treatments. *The colonies treated with oxalic acid at the end of Fall and with Thymovar or MiteAway2 (earlier in Fall) were weaker in the Spring when compared to controls treated with synthethic miticides (coumaphos: CheckMite). This negative impact of oxalic acid on the development of colonies after wintering is more important with the treatment by sublimation*.


Needless to say, the studies don't agree.



FlowerPlanter said:


> I am really surprised that anyone still does OAD. As Tenbears implies once you OAV you never go back.


Really? I did OAV this year, and it didn't take me long to want to switch to OAD. Apparently, hardly anyone still does OAV around here. It takes wayyyyyyy too much time. The spoons cost way too much. The big quicker sublimators were shown to be ineffective. Not to mention the hazards of constantly handling a hot element and producing caustic fumes...

I loved OAV... until I tried it.


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