Varroa treatment

[Jon]

Business as usual again this year.
I hardly see a mite all year and then see a daily drop of 6-8 mites in September.
I start treatment with Apiguard and get 150 from a 6 frame colony in the first 24 hours.
You can kid yourself that a colony has no mites but the reality can be quite different.

I reckon that 150 on the first day could be a total number of around 1000 which is as much as a colony could tolerate before serious damage occured.

I heard a lecture last weekend which stated that 2000 mites was the level where varroa started to pose a lot of problems re. vectoring viruses.

[Jimbo]

Hi Jon,

Careful with the treatments!
Have a read of this
http://scholar.lib.vt.edu/theses/available/etd-08162007-092313/unrestricted/lmburley.pdf

[Jon]

Lesser of two evils!
Has Apiguard been implicated in the reduction of drone fertility or queen impairment?

Your link mentioned Apilife var which is a thymol based treatment.

[Jimbo]

Apiguard has not been implicated but is Apiguard not Thymol based similar to Apilife var?
The sperm reduction and viability in Queens although shows a significant result is only a small reduction in the overall amount available and you would not be treating hives normally for varroa when there is a lot of drones about.
Now I wonder what happens to sperm numbers and viability with Oxalic, Formic, Lactic etc.

[Neils]

My personal feeling over the past couple of years is to ignore the natural mite drop. My observations compared to conventional wisdom is that observing natural mite drop, either alone or in conjunction with icing sugar dusting, severely underestimates the levels of varroa in a colony. Let colonies have a decent amount of drone brood and uncap throughout the season. I've been phasing out foundation but I give my colonies (14x12) at least 3 standard national frames at the moment so I get lots of drone brood. periodically I uncap this to check mite levels and I've been surprised at the amount of varroa in some compared to what the natural drop suggests.

[quoteI heard a lecture last weekend which stated that 2000 mites was the level where varroa started to pose a lot of problems re. vectoring viruses.[/quote]
I'm going from memory right now but I'm pretty sure we teach that 2000 is "going to die" levels of varroa rather than starting to cause problems (I believe US levels are 5,000+)

[Jon]

Hi Nellie:
It was a Swiss AMM guy called Balser Fried who quoted those numbers at the Bibba shindig last weekend. He reckoned that 2000 was on the cusp and 1000 was a safer limit.
He has used small cell for a number of years and did a talk on that as well. He found that small cell reduced overall varroa numbers but not statistically significantly.
Small cell is one of those beekeeping areas which attracts religious devotees so he wasn't deterred. From the data he showed there was certainly a slight advantage re. varroa in using small cell.

I imagine it depends on colony size as well.
1000 in a nuc would probably kill it.

2000 in September is probably survivable with immediate treatment.

[Calum]

We use almost exclusively formic acid and oxalic acid.
At the bee meeting last night one guy was saying he has treated 3 times now and had about 1000 mites each time from the same colony.
Reinvasion is a big problem here. Weak (especially wild) colonies and from colonies where 'beekeepers' are not treating at all.
I hope the weather will hold up for my seventh treatment tomorrow.

[Neils]

I've just completed an Apiguard treatment on one Colony, am halfway through on another and have just started on the colony I suspect will perhaps be far more interesting.

The colony just finished had a total mite drop over the 4 weeks of perhaps 5-6 mites. As I hadn't inspected or removed the floor during the course of the treatment there was a fair amount of debris but even carefully sifting through it I was hard pushed to find much evidence of Varroa.

The second colony that I've just swapped trays on I have taken a look at the floor in light of the results from the first colony. Counts on this one after 2 weeks were maybe 10-15 mites in total.

Daytime temperatures here are well above the recommended and I've followed the instructions to the letter but the counts on sunday were a bit of an eye opener.

The common link at the moment between these two colonies is that they are both splits from the one I had in spring and, as such, were both started either as the Queen right side of an artificial Swarm or from a frame of brood containing Queen Cells started in a Nuc. That being said, at the time these were started, neither were treated in any way and other than Drone brood uncapping neither have received any further treatment over the course of the year.

For a number of reasons, I've only just started the treatment on the "Brood" Colony from the Artificial Swarm. This has also received no treatment other than one super frame of drone brood being removed so I'm going to be very interested in the mite drop from this colony which for obvious reasons I'm expecting to be much higher.

Before the artificial swarm I treated the colony with a single tray of apiguard back in April, at that time I had 2-3 mites in total and didn't bother with the second tray. Having regularly uncapped drone brood over the season with this colony it's never appeared to reach a mite level requiring serious attention and the drone brood removal was more down to the comb getting damaged than anything else.

I'm not reading too much into this at the moment, but I was more than a little surprised by the results on two different colonies.

[Jon]

My personal feeling over the past couple of years is to ignore the natural mite drop.

Hi Nellie.
I would tend to agree with you as lack of mite drop can give a false sense of security.
I have heard several beekeepers recently state that they are not going to treat this year because of the low mite levels.
It will be interesting to se if they still have bees in April.

Between April and August I probably didn't see more than a dozen mites in total and since the Apiguard treatment started I have been removing between 50 and 150 from the inserts per day. I checked a few yesterday and most of the queens are laying.
one colony removed a lot of pupae but in general the Apiguard seems to be working well.

[beebreeder]

I raise queens and use thymol as my only treatment, I have used oxalic once and only once I had more q/less or drone layers the following spring than I have ever had, I have not used it since and things are back to normal, I know Pyretheroids seem to make drones dry! and obviously unless we are making our own f/dation or using Top bar hives!!!! then all the foundation by now has some residues in, but having said that this has been one of the best summers in years for queen rearing down south, how has it been in Scotland.

[gavin]

That was an interesting report Jimbo. In the introduction the finger was also being pointed at spring formic treatments having a very detrimental effect on drone production. I wonder if this could have worsened Eric's winter losses given that he's an enthusiast for formic acid treatment, or may even be the cause of Grizzly's drone-free colony he mentioned a while ago? From that report:

'Results of their study were discouraging. Colonies treated with formic acid removed most
of the drone eggs from combs and delayed much of the colony’s drone production. In
addition, treated colonies produced less than half as many drones as untreated colonies
(means of 1549 vs. 3800 drones, respectfully) and adult drone longevity was reduced.
Similarly, Westcott and Winston (1999) discovered that colonies treated with formic acid
had reduced brood areas compared to control colonies, which could potentially reduce
colony strength. The amount of honey produced by colonies can also be affected by
formic acid, depending on the formulation. Skinner et al. (2001) tested two formulations
of 65% formic acid: a gel, and the other with formic acid absorbed into a fibreboard pad.
Colonies exposed to formic acid in the fibreboard pad stored less honey than both control
colonies and colonies treated with the formic acid gel formulation.'

[Jon]

I raise queens and use thymol as my only treatment, I have used oxalic once and only once I had more q/less or drone layers the following spring than I have ever had,

Hi Kev.
In defence of Oxalic acid, I used it for the first time (trickled in sugar solution) last December as a follow up to Apiguard in September.
All my colonies came through winter and only one nuc was missing a queen.
I still have most of my 2009 queens and none has turned into a drone layer.
Several 2010 queens turned drone layer within weeks and these had never had a whiff of Oxalic acid.
I think you have to be careful re. cause and effect as there are multiple factors behind queen mating problems.

I reckon the Apiguard/Oxalic acid combination is one of the softest varroa treatments available

[beebreeder]

Hi Jon
Its a personal thing I think, I am not the only queen rearer in this part of the world feeling the same, I have read a report on the web on the effects of oxalic on queens and will try and dig it out and put the link up, then like me you can make your own mind up. How did your queen rearing go this year?
regards
kev

[Neils]

It will be interesting to se if they still have bees in April.

My suspicion is that (excluding other influences) yes, they'll have bees come April. How well they get on from that point remains to be seen. going to stick this in caps lest anyone misunderstand me: AS A RELATIVELY NEW BEEKEEPER I'm starting to view Varroa as a more "long term" problem. I'm starting to think that you could stop treating at all tomorrow and you'd have bees come the spring, you might get away with not treating at all next year too but after that, unless you're really lucky, you're going to be keeping, at best, some very poorly looking bees. I think this is why you see, certainly in some circles, lots of proclamations of "varroa free" bees that suddenly go very quiet after a couple of seasons.


I raise queens and use thymol as my only treatment, I have used oxalic once and only once I had more q/less or drone layers the following spring than I have ever had, I have not used it since and things are back to normal, I know Pyretheroids seem to make drones dry! and obviously unless we are making our own f/dation or using Top bar hives!!!! then all the foundation by now has some residues in, but having said that this has been one of the best summers in years for queen rearing down south, how has it been in Scotland.
You can always stop using foundation. My supers are all foundation-less and I started a couple of 14x12 brood frames without foundation for, amongst other reasons, the crap that is in the stuff, next season will be the acid test as to whether I can properly manage multiple hives without using foundation in the frames.

[Jon]

How did your queen rearing go this year?
regards
kev

I hatched over 100 grafted from my two best colonies and I divvied them up between friends and members of my BKA
I reckon about 60 were mated properly.
I kept about 25 for requeening and for making nucs but I have been combining nucs lately.
To keep the thread on topic, I think I should have treated the nucs for varroa at the end of July rather than the start of September as many of them have been building up more slowly than expected and I have seen a few bees with deformed wings on the combs.


I'm starting to view Varroa as a more "long term" problem. I'm starting to think that you could stop treating at all tomorrow and you'd have bees come the spring, you might get away with not treating at all next year too but after that, unless you're really lucky, you're going to be keeping, at best, some very poorly looking bees.

Hi Nellie
If the varroa infestation is too high they wont even overwinter as there will be no healthy longer lived winter bees raised in the Autumn.
I have been pointing out for ages to the natural beekeeping people that you would need to keep a colony for 3 years without treatment to demonstrate that it can coexist with varroa.
Swarming seems to be encouraged and this is one way of ditching 80% of the mites which are left behind under the cappings.
It is a system which selects for swarminess which is not a very desirable trait in beekeeping.

The other thing is to understand the arithmetic. At certain times of the year, mites are no problem but when brood rearing drops off in late summer the mites destroy too many pupae.

I posted this a couple of weeks ago on the bbka site.


Take a total varroa population of 400 mites in July which would not be that unusual in my colonies.
80% will be in the sealed brood, ie 320 mites.
In July the brood nest is huge, even in my native type colonies it can be over 30,000 eggs, larvae and pupae. Others may have a brood nest double that size.
If I make another assumption that the queen lays at the same rate every day, capped brood will be about 60% of the total brood area so the 320 mites will be distributed among 30,000 * 0.6 = 18,000 cells. This amounts to 1.8% of cells affected.
In addition it is known that varroa mites are 12 times more likely to be found in drone brood and there is usually lots of drone brood in a colony in July so the percentage of worker brood affected is probably much less than 1.8%

In September the calculations change quite a bit.
The queen is laying less and the brood nest is often down to 10,000 or so.
The varroa population is now 1600 of which 80%, 1280 are under cappings. There is little or no drone brood present.
The varroa now affects 10,000 * 0.6 = 6000 cells ie 21% of the brood affected. (assuming 1 mite per cell rather than multiple occupancy)

If you start with 1000 mites in July the percentage of brood affected is 4.4% in July but rises to 53.3% in September based on these assumptions.

[GRIZZLY]

As mentioned elsewhere, my drone free colony was only treated with Apistan-so no formic acid interference with the drones