The Drugs Don't Work

[fatshark]

https://www.youtube.com/watch?v=ToQ0n3itoII

Oh, but they do ... I think.

I'm an irregular reader of Beebase. They've got an active "treatment-free" sub-forum to list their colony losses ... er, I mean describe their experience in achieving mite-free nirvana.

The ever-dependable JWChesnut has recently posted a link to study from the Louisiana USDA-ARS (http://www.mdpi.com/2075-4450/8/1/9/htm) (unfortunate, but that's acronyms for you) team comparing a healthy whack of Amitraz with a light-touch IPM strategy ... essentially, sugar dusting, some drone brood removal and OMF's. Perhaps unsurprisingly, the IPM strategy was indistinguishable in terms of impact on mite numbers to truly treatment-free colonies, with mite levels reaching 15-20% by autumn. Amitraz-treated colonies had low, but certainly not insignificant, mite levels throughout ... but they were treated with Amitraz for over 100 days of the study period (mid-May to late October).

I've not used Amitraz but was surprised that 2 x 56 day treatments with the drug, whilst being dramatically better than no treatment, didn't reduce mite levels much below about 4%. Is this typical?

[gavin]

There are stories of amitraz being slow to act and of variable efficacy in the literature, sometimes thought of as resistance developing. From what I've seen the usual two strips for the 45 days or longer clean up colonies very well. I have to say I'm not a regular counter of mites, this is just the impression I get and the long period before mite problems re-emerge.

If Varroa does become resistant to amitraz in one of the countries from where the flood of imports comes, controlling this pest would get a whole lot harder.

[Mellifera Crofter]

I've been treating with Apivar for a few years now, and I've seen almost no mites in any of my colonies since using it. I was taken aback a few weeks ago when I found one colony with mites on the insert (I leave the inserts in all winter) - but I didn't see any on my last visit a few days ago. Still, I might treat this colony again in a few weeks' time. I keep the strips in for six weeks. So, Fatshark, from my experience, I think the drugs do work. But perhaps I live in an area with very little varroa.
Kitta

[Thymallus]

I used Amitraz (as Apivar strips) until a few years ago and found them most effective. But it was 1 x 6 week application not 2 x 56 day applications, which seems wrong. It was a little slower to act on the mites than bayvarol and equivalents but mite drops (in badly affected colonies ) was significant. Don't know what proportion they killed in my hives as never did a before and after counts at a level that would be accurate. Although I usually had very few drop if I did a mid-winter dribble.
Now turned to vaping which is more cost effective in the long run, although a little more labour intensive than sticking a few strips in and leaving well alone for several weeks.

[Feckless Drone]

The Apiarist (aka FS) blog (http://theapiarist.org/) has some informative and thought provoking posts about pyrethroids and resistance; bringing together different strands of the literature. I highly recommend these blogs. It raises the question about whether something like Apistan might be used again for a period since the resistant mite population will have been "evolved" out. And if you think a strategy of mixing up your varroa treatments is beneficial, for example by reducing resistance and allowing treatments at different times of the year then perhaps this miticide is worth consideration again. One issue is that if the miticide residues are present in wax then the resistant mite population will have been selected for and since all of my foundation is from commercial sources then I am a bit hesitant until I find out more. Is the residual miticide present at a significant level?

An issue is also getting everyone in a particular area to treat the same way and at roughly the same time which might reduce the transfer of resistance. Here in Tayside we are all pretty much in flying range of bee farmers and their practice re varroa could influence what we might do. I cannot recall if C4U posted on this issue but, (before we lose him to the season) what is your strategy for varroa management?

I have settled on a mid-winter oxalic acid treatment, and a late summer/autumn Apivar for the past 3 years. In future I'll mix in with Apiguard and if something desperate happened early on I would use formic acid (I have found this harsh on the colonies, but maybe overdid the dose).
The miticide in Apivar is called amitraz - and it is widely used in the US for cattle treatments and drug resistant strains of ticks have been found so at some point also Apivar might be problematic in beekeeping.

[The Drone Ranger]

This might be wrong but last year people were reporting low mite levels no drops etc
When that has happened in the past then the following season the mite population has been high
I'm judging from the posting over the years on SBAi

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[alancooper]

I alternate treatments during the year ("integrated" approach?), but this spring (after a very mild winter, a pre-Christmas vape and a mid-Jan vape) my mite levels crept up (10-20), coinciding with drones hatching. Mite levels were greatest in my two poly hives. I treated all hives (5) with MAQS - hundreds of mites dropped. I have no disease signs but one of the poly hives is not filling its super (Q is OK and colony strength/brood/laying are good). I wonder if mite levels have risen greatly at a regional scale this year?

[madasafish]

This might be wrong but last year people were reporting low mite levels no drops etc
When that has happened in the past then the following season the mite population has been high
I'm judging from the posting over the years on SBAi

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I had 2015 as low mite levels and 2016 as very high.

[The Drone Ranger]

Maybe it's when there appears to be less varroa they get less attention and they florish

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