Varroa Control

I am an experienced beekeeper and consider I take good care of my bees, 5+ hives on the NW coast of Scotland and up to a few years ago the area was varroa free. Yesterday after a decent stretch of low temps I applied OA by sublimation, I do this every winter. The resulting 24hr drop was quite surprising given my regular monitoring and management of the dmd. Throughout the brood rearing period of the year I place the yellows under maybe every 4 weeks or so and chart the drop. I see the usual trends and suppress the varroa with icing sugar which has worked well. Going into this winter the dmd was 2/3 per day. Today after yesterday's sublimation I had some dmds up in the 90s and 70s, quite a surprise, other hives were up of course but in the expected range after a sublimation.
I have been following Sussex Uni's recent papers on the use of OA and how sublimation is the best method of the three. If as I am lead to believe I have killed off ~97% of the phoretic varroa I am trying to calculate if and when I should apply another treatment in an attempt to remove as much as possible before the Q starts laying. Popular current thinking is ~6 days after first treatment and then 15/16 days after the second treatment which seems logical.

Would anyone like to comment on the expected effectiveness and timing of this program.

Thanks,

M

Hivemaker on the BKF has reported 3 treatments at 5 day intervals if brood is present. I think he determined this empirically. I suspect the level and availability of brood and the duration of the phoretic phase (which isn't constant) are likely to mean that no single answer is likely to be correct. I've used 3 x 5, 4 x 5 and multiple treatments with 4 or 5 day intervals. I've not aware any is better or worse. Daily mite drop falls off pretty quickly after a single treatment, so I'd not want to leave a 15/16 day gap ...

The late summer/early autumn treatment is the most important as this is the one that hammers down the mite population before the winter bees are exposed to viruses.

It is really sad that people continue to take bees into previously Varroa-free areas. Anyway, you asked for comments on your plans.

The timing between treatments - why not repeat twice (or more) at roughly 6 day intervals? Then you've covered a full cycle of sealed brood even if the queen is laying. A few of my crown boards have some detectable warmth so I think some colonies here are brooding. Of course, I can't recommend multiple sublimation, as the only legal way to treat is to use ApiBioxal according to the instructions, and they say sublimate only once per year. For OA treatments I just treat by the calendar rather than after cold weather. Daylength seems to have more influence on brooding than recent temperature and colonies will just briefly restart brood rearing at random times no matter what the weather.

Your results are probably proof that icing sugar does not work as a Varroa control. There have been papers published on this. In much of the year most mites will be inside sealed cells and therefore immune to powdered sugar. Even those out of cells may not be affected. Some mites are firmly clamped on and lodged between abdominal segments so I doubt that a high proportion of them are susceptible to the icing sugar. Use it only to monitor mite levels, and monitoring that way is much better than looking for mite fall onto a sticky board ... and that is better than mite fall onto a dry board.

Finally, the University of Sussex's study is just one study amongst many. Even that study doesn't report a significant difference for most parameters between trickling and sublimating. Colonies do seem stronger in spring after sublimating but they used a standard 50 ml for trickling which is significantly more than most of us would use - so it wasn't a fair comparison. However sublimation is a good method so no need to change now.

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Originally Posted by fatshark

The late summer/early autumn treatment is the most important as this is the one that hammers down the mite population before the winter bees are exposed to viruses.

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Do you use sublimation for this too? Just considering my options ...

Yes. For the last couple of years.

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Originally Posted by fatshark

Yes. For the last couple of years.

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Do you feel/know that this is more efficacious than Autumn Apiguard?

No I don't. It's certainly 'good enough' and mite levels have been very low. However, I've done no side-by-side comparisons that would stand any sort of scrutiny.

However, unlike Apiguard, OA (Api-Bioxal etc.) treatment by vaporisation does not seem to stop the queen from laying as it often does with Apiguard. Since treatment usually coincides with the important egg-laying for generating the winter bees I think this is a significant benefit.

The other thing I have to consider is temperature. Having moved to balmy Fife in 2015 the autumn temperatures are sometimes borderline for Apiguard treatment after the summer honey is taken off. I don't currently take my bees to the heather, but once you're into September the likelihood of getting the necessary 15C for Apiguard is much less than it was when I was living in the Midlands.

This is a summary of Jennifer Berry's work re the futility of sugar dusting.

Also, although the NBU recommend estimating mite levels by counting mites which drop through the mesh, my experience is that this is completely inaccurate.
You don't see a mite for months then you get a massive drop when a treatment is applied.
Sugar shake with a measured sample of 300 bees gives a fairly good estimate of mite levels.
There is info onthe NIHBS site here

Agree with Gavin re the LASI research. Very easy to find flaws in the methodology and even on their own results there is little or no difference between trickle and sublimation although the press releases do not reflect that reality.

Look at the graph from the paper.
Trickle at recommended dose kills 93.3% of mites
Sublimation at recommended dose kills 93.1%

At the highest doses in that paper there was no statistical difference between trickling, spraying and sublimation. I agree that the latter has been overhyped and many have ignored the absolute requirement for removal of sealed brood to achieve the 93+% levels they're reaching.

My comments above were restricted to comparison between sublimation and Apiguard during the autumn.

I agree that the estimates from natural mite drop are a bit hit and miss - it's only really any use after treatment has been applied.

Finally, 50ml for trickling in midwinter may not be too far off for Sussex ... when I lived much further South it wasn't unusual to have 7-8 seams of bees in strong colonies in early January. What is known is that trickling is not good for unsealed brood ...

Thanks for all the helpful responses, I will take them into account. My inclination now after receiving other inputs is to conduct another sublimation 6 days after first, with a third again 6 days on again.

M

Just watch how you are sublimating. If using a 12v pan under an open mesh floor it's worth increasing the amount of OA as a lot will condense onto the wire mesh. Meaning that the bees (or should that be the mites) might not receive the optimal dosage of OA to get a 97% kill rate. It doesn't appear to harm the bees to use more than the 2 (or is it 2.2) gm optimal dosage that everyone seems to have adopted. That was the minimum concentration to give that kill rate, higher doses don't seem to affect the bees but will ensure you are getting enough into your hive to compensate for the stuff that isn't.
I think it may help explain why some find vaping very successful and others find they still have high varroa loads afterwards.

I think the LASI people used up to 4.5g and there's data on Randy Oliver's site of using 2.8g. There's also a lot of active and reasonably well informed discussion on Beesource (just steer clear of the TF threads which usually make pretty grim reading).

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Originally Posted by fatshark

No I don't. It's certainly 'good enough' and mite levels have been very low. However, I've done no side-by-side comparisons that would stand any sort of scrutiny.

However, unlike Apiguard, OA (Api-Bioxal etc.) treatment by vaporisation does not seem to stop the queen from laying as it often does with Apiguard. Since treatment usually coincides with the important egg-laying for generating the winter bees I think this is a significant benefit.

The other thing I have to consider is temperature. Having moved to balmy Fife in 2015 the autumn temperatures are sometimes borderline for Apiguard treatment after the summer honey is taken off. I don't currently take my bees to the heather, but once you're into September the likelihood of getting the necessary 15C for Apiguard is much less than it was when I was living in the Midlands.

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Good point about the queen going off-lay. I will do a 3 x sublimation this August.
What are your thoughts about doing it when feeding? This year it will be fondant instead of syrup.

I've treated when feeding. I only use fondant. No problems as far as I'm aware. I also used to feed when treating with Apiguard.

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Originally Posted by fatshark

I think the LASI people used up to 4.5g and there's data on Randy Oliver's site of using 2.8g. There's also a lot of active and reasonably well informed discussion on Beesource (just steer clear of the TF threads which usually make pretty grim reading).

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I've been following the recent glycerine / oxalic acid threads on beesource with interest;
"25 ml food grade glycerin warmed, 25g of Oxalic mixed til dissolved, soak in per shop towel then press out excess. Each towel should hold 25g treatment, total towel weight of 30g. Place towel ontop bar of hive which will be removed by the bees over 3-4 weeks. "
Copied from beesource http://www.beesource.com/forums/show...gap-flyswatter

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Originally Posted by mbc

I've been following the recent glycerine / oxalic acid threads on beesource with interest;
"25 ml food grade glycerin warmed, 25g of Oxalic mixed til dissolved, soak in per shop towel then press out excess. Each towel should hold 25g treatment, total towel weight of 30g. Place towel ontop bar of hive which will be removed by the bees over 3-4 weeks. "
Copied from beesource http://www.beesource.com/forums/show...gap-flyswatter

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Yes, the original source used cardboard strips and claimed this worked well. havent tried it as my bees are well OA dosed at the moment but you can bet your life that someone will market this in the UK and sell paper soaked towels with vet approval for big bucks :)

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Originally Posted by busybeephilip

big bucks :)

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For sale: the BEST Varroa treatment package based on the miracle of crystal healing. With simple self assembly instructions, enough for 50 treatments. Includes 1 packet of paper towels (surcharge for blue), safety gloves, glycerin, the magical oxalic acid crystals, pure and natural Scottish water.
Price: £100 plus vat. Must collect. No time wasters.

Probably one well timed oxalic treatment is good enough
Sugar dusting is messy and attracts wasps and other pests
I don't think there's a case for using multiple oxalic treatments when there is brood
That's just the wrong tool at the wrong time

Has anyone tried Stratiolaelaps scimitus as a means of controling varrora. A predatory mite or Entomopathogenic fungi.

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Originally Posted by The Drone Ranger

Probably one well timed oxalic treatment is good enough
Sugar dusting is messy and attracts wasps and other pests
I don't think there's a case for using multiple oxalic treatments when there is brood
That's just the wrong tool at the wrong time

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Experience with doing exactly this with vaping in Sept when there is brood present is that it does work and works well. You just need to be sure you are getting the correct levels of vaporized OA to the bees and you need 4 vapes to get the majority of the emerging varroa.
However, you may be referring to other types of multiple OA treatments in which case ignore this.

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Originally Posted by Greengage

Has anyone tried Stratiolaelaps scimitus as a means of controling varrora. A predatory mite or Entomopathogenic fungi.

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Our local NBU bee inspectors were giving out packets of a predatory mite that may have been called something like that or very similar, a few years ago.
Tried it in a few of my hives but couldn't see much difference in a varroa levels.
They aren't dishing it out any more...

Thanks for the Randy Oliver link really interesting, he suggests that the bees happily rear brood under the towels. If DR's about, what do you think about putting an Ox/Gly towel on top of the Snelgrove top section when making the split.