Repeated doses of oxalic acid are ineffective when sealed brood is present.

[BeeKeyPlayer]

https://academic.oup.com/jinsectscience/article/22/1/15/6523139
This study suggests that repeated does of vaped oxalic acid do little more than contain (rather than control) varroa when there is sealed brood in a hive. The researchers used a dose of 1g per brood box seven times at 5-day intervals and found that the level of mites stayed the same (and also that adult bees were not adversely affected); at the same time, mite levels increased in the control colonies. They speculate that the 1g dose may be too small given that others have had success with 2.5 and 4g doses. This might explain the (anecdotal) findings of many beekeepers that repeated treatments are successful in colonies with sealed brood.

A bit of a lost opportunity not to have done this trial with the more usual larger dose (c.2.5g), four times at 5-day intervals?

(Moderators: this article out in January so apologies if it has already been aired here.)

 

[Nige.Coll]

Other research has shown the efficacy of up to 70% for multiple treatments of OAV. If I remember right that used a larger dose.
I don't have the research paper to link here.

 

[Anduril]

https://academic.oup.com/jinsectscience/article/22/1/15/6523139
This study suggests that repeated does of vaped oxalic acid do little more than contain (rather than control) varroa when there is sealed brood in a hive. The researchers used a dose of 1g per brood box seven times at 5-day intervals and found that the level of mites stayed the same (and also that adult bees were not adversely affected); at the same time, mite levels increased in the control colonies. They speculate that the 1g dose may be too small given that others have had success with 2.5 and 4g doses. This might explain the (anecdotal) findings of many beekeepers that repeated treatments are successful in colonies with sealed brood.

A bit of a lost opportunity not to have done this trial with the more usual larger dose (c.2.5g), four times at 5-day intervals?

(Moderators: this article out in January so apologies if it has already been aired here.)

1g is their legal dose.

 

[Erichalfbee]

(Moderators: this article out in January so apologies if it has already been aired here.)

No problem.
There’s more here


https://beekeepingforum.co.uk/threads/aficionados-of-oxalic-sublimation.51127/

 

[ericbeaumont]

1g is their legal dose.

How did they arrive at that amount? After research, or arbitrarily?

 

[Anduril]

How did they arrive at that amount? After research, or arbitrarily?

Most probably arbitrarily.

 

[BeeKeyPlayer]

No problem.
There’s more here
https://beekeepingforum.co.uk/threads/aficionados-of-oxalic-sublimation.51127/

Thanks for all this. I'm working my way through this and others in the thread. (How to skim videos?) I see everything in the paper above has been thoroughly covered already.

 

[Nige.Coll]

1g is the recommended dose when you buy a varrox.

 

[user 819]

1g for subliminating isn't enough for sealed brood and repeating the process over a brood cycle, Al Toufailia et al have carried out the science on this back in 2015 and before.
1g is enough to dislodge parasitic mites in a super but a BB requires 2.25g per application.

This became available 5 years ago.
Beekeeping - Effect of oxalic acid on the mite Varroa destructor and its host the honey bee Apis mellifera (apiservices.biz)

 

[user 819]

The varrox 1g is for a brood less one off application........ of a super ?

 

[polymath]

Thanks good stuff, and yes the research does say you need more than 1g