Varroa destructor against oxalic acid

Hello all,

Was watching a video on youtube last night before bed that referenced this article. Thought I would share this with the forum.


Maggi, M. D., Damiani, N., Sergio, R. R., María, C. B., Szawarski, N., Mitton, G., … & Eguaras, M. J. (2017). The susceptibility of Varroa destructor against oxalic acid: a study case. Bulletin of Insectology, 70(1), 39-44.


I got a little lost reading the research but from what I gather it reduced the amount of varroa though did not eliminate it.What was your take?

The bottom line for me was that if you treat a hive with oxalic acid (OA) for 8 years, the oxalic seems to remain as effective against the Varroa as it is after the first treatment. In other words, there was no evidence of the development of resistance by Varroa to OA in their study.

My major criticism of the method is that the treatment and control hives were in the same apiary. That means that mites which had been in a treated hive could fairly easily transfer to an untreated hive. As the study was a “snapshot” population study, and not a vertical study (done over time), it may not truly reflect lack of resistance, just that all of the mites in that apiary had the same sensitivity to OA.

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I think you missed the statement where the control hives were I believe 900 KM away but in the same climate zone.

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You are correct, I did! :blush:

Maggi is a very well-recognized beekeeper, and he is respected by Randy Oliver, so I should have known that he would do it properly. :smile:

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It was also done over 8 years!

They don’t show the annual data though. I want MOAR data!!! :smiling_imp: The data that they show are only from 2006 and 2007. :wink:

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Resistance to oxalic is highly unlikely because applied as a vapour it burns the mites’ feet and mouthparts. It’s nigh on impossible to acquire immunity to this sort of physical assault. In addition it is tolerated really well. I have a couple of queens that have been exposed one, to 12 vapes and the other to 15 and both are still going strong.


So many points to like about your post Dee - Happiest to hear about your queens but it’s also quite gratifying to be reminded of the way oxalic acid actually works :smiling_imp: Studies are of course important, but sometimes I think people lump OA in with miticides.