Still big varroa drop

[charlievictorbravo]

This was my plan in June this year- from an earlier thread



This was my rationale for whether to re-treat or not in June:

Ah, thanks for that - makes sense. I might try that next year. alongside natural mite drop to see if there's any "amateur science" correlation.

CVB

 

[rook66]

Have vaped a couple of hives 5 or 6 times and continues still large drop. Bees now clustering but probably still brood, so should I just keep vaping or wait until end of December when hopefully no brood?

Obviously all the mites are not being hit and breeding continues, I think it was Finman who posted that mites are still falling weeks after oa vaping. Is it possible they are still able to breed despite treatment. Having the bees broodless being the key to success.

 

[oxnatbees]

I never have varroa problems. Almost my stock is from wild swarms - sometimes I can see the nest and the householder says "oh yes they have been living there unmanaged for years" - the rest are from other no treatment beeks. Varroa just isn't an issue in our area. I think another key aspect is not encouraging them to breed all the time: brood breaks break the varroa breeding cycle.

I tried Buckfasts originally - they couldn't survive no-treatment.

 

[linoleum bonypart]

Not long til December with cold weather coming forget about it until then and vape

 

[Monsieur Abeille]

Friend I passed my hives to has one that continues to have a pretty heavy drop after 5 treatments with a (roughly) 5 day gap. Just came on here in fact to see if there were any limits I/she should be aware of.

Think I'll probably recommend one more vape then leave until the depths of winter before doing again, unless there are strong suggestions for an alternative treatment (I've only used Apilife Var and MAQs before as alternatives to oxalic, and I dont think either of those can be used at these temperatures).

Its all most odd, is there some disproving of the efficacy of oxalic vaping going on?

 

[Swarm]

It's not so much OAV being ineffective, it has to be working to knock down the number of mites reported but for this to be going on week after week, with counts in the thousands, the question is where are these mites coming from?

 

[Beefriendly]

the question is where are these mites coming from?

This time of year....not very far away!
Robbing isn't always the answer.
I think knowing the original population of mites might provide the answer.
In my case there was a very heavy initial infestation in the recalcitrant colony. My thoughts were there is a limit to how many mites are killed by any one dose of OA and there are also limits to the effectiveness of OA treatment, particularly with double brood boxes, get your vaping wrong and it will not be very effective. Using a sublimox on mine, this probably wasn't the issue.
I ended up giving my bad hive 10 vapes to get the number down to single figure drops, so it does work....
Remember these are exceptions; rather than the rule, most of my colonies were dropping nowt after 3 vapes.

 

[mazzamazda]

Friend I passed my hives to has one that continues to have a pretty heavy drop after 5 treatments with a (roughly) 5 day gap. Just came on here in fact to see if there were any limits I/she should be aware of.

Think I'll probably recommend one more vape then leave until the depths of winter before doing again, unless there are strong suggestions for an alternative treatment (I've only used Apilife Var and MAQs before as alternatives to oxalic, and I dont think either of those can be used at these temperatures).

Its all most odd, is there some disproving of the efficacy of oxalic vaping going on?

Amitraz treatments arent particularly temperature dependent, as long as not clustered

 

[mazzamazda]

This time of year....not very far away!
Robbing isn't always the answer.
I think knowing the original population of mites might provide the answer.
In my case there was a very heavy initial infestation in the recalcitrant colony. My thoughts were there is a limit to how many mites are killed by any one dose of OA and there are also limits to the effectiveness of OA treatment, particularly with double brood boxes, get your vaping wrong and it will not be very effective. Using a sublimox on mine, this probably wasn't the issue.
I ended up giving my bad hive 10 vapes to get the number down to single figure drops, so it does work....
Remember these are exceptions; rather than the rule, most of my colonies were dropping nowt after 3 vapes.

This is my problem with oav, you need to test before and after, massive job and thats before the one full month in a year treating the hives.

I actually managed well vaping with double brood in March this year, seemed to work well. I cant afford a single hive to be loaded as afb knocks on the door of a week hive and thats ongoing right now.

I do agree there must be limits to what oav can deal with, strangely though it doesnt seem to have the same irregularities when broodless.

I just cannot imagine doing 10 vapes, sublimox or not.

 

[Beefriendly]

I do agree there must be limits to what oav can deal with, strangely though it doesnt seem to have the same irregularities when broodless.

I just cannot imagine doing 10 vapes, sublimox or not.

Good point.....only did the 10 because hive in my back garden and wanted to understand whether OA vaping would get the levels down and could the colony take so many vapings...yes they did and yes the levels did get there...whether they survive the winter...we shall see.
Current thoughts are it works well on most hives...might save some time by going to strips for those hives that still drop high levels after 3 vapes.
There is something going on with some colonies...my own experience suggests it is to do with an initial extremely high level of varroa within the colony. I don't buy into this robbing form some totally unknown source that has high varroa, bit of a cop out explanation IMHO. But I can also see from others that inefficient vaping may also be contributory.

 

[Beefriendly]

This is my problem with oav, you need to test before and after, massive job a

Not sure this is a big issue for me. My hives have open mesh floors and I vape with the "varroa" boards in. Next visit it's easy to slide out and check what the drop levels are.
The counting before is the issue for me...being lazy...the treatment is scheduled into the year. My notes from this year tell me I need to be more on top of the current levels. !more work!

 

[mazzamazda]

Not sure this is a big issue for me. My hives have open mesh floors and I vape with the "varroa" boards in. Next visit it's easy to slide out and check what the drop levels are.
The counting before is the issue for me...being lazy...the treatment is scheduled into the year. My notes from this year tell me I need to be more on top of the current levels. !more work!

Thats what I meant counting, before and after. Alcohol wash. More expensive than the Amitraz alone.

 

[mazzamazda]

Good point.....only did the 10 because hive in my back garden and wanted to understand whether OA vaping would get the levels down and could the colony take so many vapings...yes they did and yes the levels did get there...whether they survive the winter...we shall see.
Current thoughts are it works well on most hives...might save some time by going to strips for those hives that still drop high levels after 3 vapes.
There is something going on with some colonies...my own experience suggests it is to do with an initial extremely high level of varroa within the colony. I don't buy into this robbing form some totally unknown source that has high varroa, bit of a cop out explanation IMHO. But I can also see from others that inefficient vaping may also be contributory.

I'm not sure about the robbing either. I know from personal experience colonies collapse into others though, I have actually seen it. All it takes is one colony with a high load, collapses into another with up to 12 mites per bee, within one brood cycle that in turn collapses, usually without much warning. I cannot afford that rogue high load hive. Another thing i have noticed is varroosis is still visible during oav treatments, with a high mite drop, that is a first for me.

 

[Beefriendly]

. All it takes is one colony with a high load, collapses into another with up to 12 mites per bee, within one brood cycle that in turn collapses, u

Fortunately that is not what I've experienced.
In an apiary with about 10 hives I've had an odd one with very high varroa drops after OA treatment. This colony didn't collapsed nor did the varroa increase in numbers in the adjacent hives. Perhaps initial numbers not high enough to cause colony collapse?
Overall I'm very happy with OA vaping, but there are these "rogue one" colonies that I don't yet understand.

 

[Erichalfbee]

Overall I'm very happy with OA vaping, but there are these "rogue one" colonies that I don't yet understand.

Same here
Next year I will put Apitraz in any still dropping high numbers after four vapes

 

[jeff33]

When they jump onto the pan they do, I've had it 3 times in less than a year

That's why I vape mine from underneath. I put the bottom tray in place which has a small cut big enough for the vape to slide in. I don't even need to hold the vape, I can get on with something else.

 

[Beefriendly]

Same here
Next year I will put Apitraz in any still dropping high numbers after four vapes

Yes, I think I will do the same. Although my future aim is to treat between flows as well "and count more often"...an often forlorn resolution when the season gets underway.

 

[Beefriendly]

Thats what I meant counting, before and after. Alcohol wash. More expensive than the Amitraz alone.

I just rely on the inaccurate drop counts onto a board. They give a feel for whats happening. Although in the case I had it was DWV in the bees that gave the game away...they were in trouble.
I don't (although i should) do more alcohol washes, but as the number of hives increases the time involved is not worth it.

 

[charlievictorbravo]

I've been following and have contributed to several threads featuring discussion about problem of mites in certain hives refusing to play by the rules.

On reviewing those threads, I extracted the list below of most of the possible explanations offered for this phenomenon. Some of these are a bit spurious but I've included them for the sake of completeness. So here goes:

Possible Reasons for Difficulty of Clearing Varroa Mites from Hives after Many Oxalic Acid Treatments

1. The hives were very productive with many bees present. It is possible that all these bees blocked the pathways for the rising Oxalic Acid vapour. So the top of the deep hives do not get coated in the vapour/micro-crystals, allowing the mites several cycles of reproduction.
2. The bees found a hive weakened by Varroa and robbed it out, bringing with them many stowaways.
3. Because of the large bee population, there must also have been a large number of Varroa mites. The mites simple out-bred the ability of the Oxalic Acid to kill them, perhaps also in combination with 1. above.
4. Is some portion of the OA dose being lost by boiling over the heated dish on the vaporiser before reaching sublimation temperature (157°C), possible associated with damp OA crystals and/or the loss of the two water molecules in the OA Dihydate (at 101.5°C)
5. Has a change occurred with the mites such that they are not taking a 5 day phoretic break outside the comb and are not thereby being vaped by OA?
6. In a heavily populated hive with a large brood nest, it is possible that the vapourised OA from a passive (i.e. not pressurised) vapourisor does not reach the extremities of the hive and the phoretic mites in those areas escape to reproduce again for another cycle or two.
7. If vaping through the Open Mesh Floor in cold weather, perhaps a significant proportion of the active ingredient is condensing on the mesh and therefore not reaching the brood box.

CVB

 

[Eyeman]

Nice summary
Any suggestions on how we investigate further?
Or do we do as Erica suggested and limit our OAV to 3-4 sessions and if there is still a large drop then switch to something else?