Advice re varroa treatment

[Bryang]

I have done a search, but can't find the answer..... Is there a limit on how many times I can treat my hives with oxalic using a evaporating "poker"?
listed below is the drop per hive over six treatments

H1(B+half) H2 (B) H3(BB)
40+ 30+ 45+
100+ 50+ 80+
600+ 50+ 160+ used new "poker" for this one on.
400+ 20+ 200+
150+ 30+ 80+
80+ 65+ 100

All treatments with 4 day gaps between them
using 3 x1g tabs, except last treatment where I used 4 tabs.

Thanks in advance.

Bryan

 

[Eyeman]

Hi
Your 6 treatments at 4 days apart has treated one complete 'drone' brood cycle.
If the treatment when then is a lot of brood around actually worked then I would have thought you have treated them enough! Clearly you have knocked a fair few mites down. Whether this is too late in the day to ensure you get heathy bees going into winter- time will tell.
You may want to think about re-treating when you think there might not be much brood around. I've ear marked 3 dates in December, 7th,14th and 31st.

 

[mbc]

Hi
Your 6 treatments at 4 days apart has treated one complete 'drone' brood cycle.
If the treatment when then is a lot of brood around actually worked then I would have thought you have treated them enough! Clearly you have knocked a fair few mites down. Whether this is too late in the day to ensure you get heathy bees going into winter- time will tell.
You may want to think about re-treating when you think there might not be much brood around. I've ear marked 3 dates in December, 7th,14th and 31st.

+1
This about covers it

 

[Fusion_power]

Mites spend an average of 4 days phoretic and 11 (worker) or 14 (drone) days in capped cells. With a 4 day treatment cycle, similar numbers of mites will drop on the 1st, 2nd, and 3rd treatments, but should show a significant drop on the 4th and subsequent treatments. This will be the cycle(s) where the mites killed by the first treatment are reflected in the numbers.

 

[Finman]

.
One oxalic acid, trickling and gasifying, drops mites during next 3 weeks and even more. Biggest drop is 2 weeks after treatment.

If you have empty combs under active combs, lots of mites drops into cells, and you may shake tens from combs. But they have died several months before counting.
.

 

[Finman]

.
One researcher in Maine university writes, that in Europe practice is that hives are fumigated weekly.

Where that 4 days apart comes, it would be good to know.
.
OxaVap seller company speaks about weekly treatments.

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[mbc]

.
One researcher in Maine university writes, that in Europe practice is that hives are fumigated weekly.

Where that 4 days apart comes, it would be good to know.
.
OxaVap seller company speaks about weekly treatments.

.

Mites can dive straight into about to be capped brood from emergence but they have less breeding success than those who spend some time in the phoretic stage.
The answer to the ops question about limits of oav on the bees is that there doesn't seem to be any and that it's very difficult to over treat them with oav.
Weekly fumigation is old news and let's the mites carry on breeding if there's brood available to breed in.
As evidence mounts from people's counts post treatment I believe the effectiveness of oav when there's brood is not good enough to justify the effort in comparison to more persistent treatments like thymol or formic acid, oav being a suitable tool for mopping up any remaining mites once the bees are broodless.
Time will tell but I'm sure the repeated oav treatment when there's brood fad will fade with time, especially in areas with high humidity (=Wales ) as the effectiveness of the oxalic crystals is very short lived as they rehydrate.

 

[Bryang]

Thanks all for your informative replies. Will treat them again in Dec as Eyeman suggests and hope that there is less brood in the hives at that time.
Again thank you all

Cheers

Bryan

 

[Finman]

Mites can dive straight into about to be capped brood from emergence but they have less breeding success than those who spend some time in the phoretic stage.
The answer to the ops question about limits of oav on the bees is that there doesn't seem to be any and that it's very difficult to over treat them with oav.
Weekly fumigation is old news and let's the mites carry on breeding if there's brood available to breed in.
As evidence mounts from people's counts post treatment I believe the effectiveness of oav when there's brood is not good enough to justify the effort in comparison to more persistent treatments like thymol or formic acid, oav being a suitable tool for mopping up any remaining mites once the bees are broodless.
Time will tell but I'm sure the repeated oav treatment when there's brood fad will fade with time, especially in areas with high humidity (=Wales ) as the effectiveness of the oxalic crystals is very short lived as they rehydrate.

Rehydrated oxalic acid?

When you buy ready water solution from Italy


Wales has moist weather.... Have you looked Europe map, how much countries exist on sea coast?

Let is be so.


Time will tell.... Vaporazing has been done 30 years

.

 

[Finman]

.
From where that every every fourth day's treatment comes. Is it research or self made decision?

And you should check you chemistry knowledge about oxalic acid.

Dihydrate is normal

Oxalic acid does not loose its acidity in moist climate. Store it inside.


.

 

[Bryang]

To clarify.... I treated with a 4 day gap between treatments or to put it another way every 5th day... as instructed in a previous thread.

Bryan

 

[Finman]

To clarify.... I treated with a 4 day gap between treatments or to put it another way every 5th day... as instructed in a previous thread.

Bryan

In other countries it is used once a week.

Oxalic affects long time.
.
But an American researcher writes that it is very difficult to find tested advices about vaporatzing.
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[mbc]

.

And you should check you chemistry knowledge about oxalic acid.

Dihydrate is normal

Oxalic acid does not loose its acidity in moist climate. Store it inside.
.

Condensed oxalic vapour loses its activity against varroa very quickly once damp (I think!), I've not been able to find anything published beyond it fitting with loads of anecdotal reports on the interweb, but that's where my money is.

 

[Erichalfbee]

Time will tell but I'm sure the repeated oav treatment when there's brood fad will fade with time, especially in areas with high humidity (=Wales ) as the effectiveness of the oxalic crystals is very short lived as they rehydrate.

Isn't the inside of a hive pretty humid no matter what the weather outside?

 

[mbc]

Isn't the inside of a hive pretty humid no matter what the weather outside?

The nest maybe, unoccupied comb and internal walls will be affected by atmospheric humidity.

 

[fatshark]

Randy Oliver over at ScientificBeekeeping has lots on OA treatment, including describing the studies by Radetzki which are tricky to find online. There's also this quote Heinz Kaemmerer of Heilyser Technology Ltd. says: “We treated several colonies for 3 months during winter, once a week with the vaporizer and all colonies survived.” “With brood, colonies can be treated with the right amount of OA 3 to 4 times, a week apart; there is no harm to bees, queen or brood.” Medhat Nasr confirms that vaporized oxalic is very gentle to the bees.

 

[Finman]

Condensed oxalic vapour loses its activity against varroa very quickly once damp (I think!), I've not been able to find anything published beyond it fitting with loads of anecdotal reports on the interweb, but that's where my money is.

Consended, do you mean anhydred? It takes moisture from air..

That is why anhydred is not used in practice.

Condensed oxalic acid does not loose its activity. It works as well against the mite.
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Guys write what ever on forums. That is why you should go to orignal researches.

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[Finman]

Isn't the inside of a hive pretty humid no matter what the weather outside?

So it is. I have never seen that climate or humidity affects on efficacy of oxalic acid.

 

[Finman]

The nest maybe, unoccupied comb and internal walls will be affected by atmospheric humidity.

No. Absolutely no. Trickling works in every country with same recipe. It has been used almost 20 years in Europe. It was invented in Italy 1997 by bee professor Nanetti.

One method is to spray 2-3% water solution without sugar.

Then, vaporizing makes acid dust everywhere into the hive. I bet that water spraying works same way when water dryes up in the heat if hive.

 

[Eyeman]

One oxalic acid, trickling and gasifying, drops mites during next 3 weeks and even more. Biggest drop is 2 weeks after treatment.

Finman
If OA has such a long lasting effect against mites then there should be no argument against using it over 3-4 cycles when brood is present.
Why do you think we haven't seen any research to confirm its effectiveness in this situation?