dead varroa

[Nige.Coll]

http://www.beekeepingforum.co.uk/attachment.php?attachmentid=10981&stc=1&d=1413195373


Varroa kill after second treatment with OA vapourisation. The first kill was more but i didn't get a pic.

the varroa calculator said to treat in 9 months after monitoring the drop.

 

[sussexbaker]

Isn't it a bit early to carry out OA vapourisation? At the recent LASI workshop they suggested that at higher ambient temperatures there was a marked increase in bee fatality (I have a memory of the figure of 10c being the top end of the range they'd treat in though I can't find the actual data from their study anywhere) as well as the obvious issue of capped brood.

I'm planning on treating using sublimation in December so would be very interested to hear of your experiences with doing it.

 

[jenkinsbrynmair]

the varroa calculator is based on varroa drop from natural mortality not from treatment mortality thus any calculations are meaningless

 

[TryingToLetThemBee]

What is that? 400 mites. More before say 600. Times 5 because first off you killed the phoretic ones and you have a colony on the way to my problem child: 3,000 mites. Good luck. Which vaporiser do you use?

 

[Hivemaker.]

Isn't it a bit early to carry out OA vapourisation?

No, earlier the better to get healthy winter bees.

 

[sussexbaker]

No, earlier the better to get healthy winter bees.

Even setting aside the bee fatality haven't you've still got the issue of Varroa in the capped cells? I understand the need for treatment if you've an unacceptable level of Varroa going into winter, it's just that from what I've read/been told OA sublimation isn't the right treatment for this time of year.

Just thinking it through I guess it depends on how long Varroa spend outside capped cells. What percentage of the total Varroa population of a colony is present as phoretic mites while there is brood present? Hmmmm

 

[Hivemaker.]

Even setting aside the bee fatality haven't you've still got the issue of Varroa in the capped cells?

Have not noticed any bee or brood fatality at all, even with well over treating to see if there would be any, three treatments five days apart pretty much clears out most of the varroa.

 

[sussexbaker]

Have not noticed any bee or brood fatality at all, even with well over treating to see if there would be any, three treatments five days apart pretty much clears out most of the varroa.

Bee fatality was something that was mentioned as an aside at the LASI IPM workshop, but my quick bit of Googling can't turn up anything. Is it your first year of treating with it? From memory they used colony mortality by the following year as an indicator of leathality of treatments, although I'm not sure if that was the case with the higher temperature stuff.

Happily I've very low Varroa drops (the advantage of only just starting) at the moment so my plan was OA sublimation at Christmas. If higher temperatures aren't an issue then using it at other times in the year seems like a winner.

 

[Hivemaker.]

Bee fatality was something that was mentioned as an aside at the LASI IPM workshop, but my quick bit of Googling can't turn up anything. Is it your first year of treating with it?

No, not my first year, done around five thousands treatments so far, and no problems at all..(not on one hive) and up to seven over dose treatments on forty colonies seven days apart.

The only oxalic method i have ever had problems with is the trickle method.

 

[Minxpinx]

That is a very similar situation that I'm looking at in my hive that I treated on Saturday. ( on the advice of Hivemaster - thank you). Will be doing the next treatment in a couple of days. Hoping that the colony gets a chance to rear some healthy winter bees now.

 

[Nige.Coll]

What is that? 400 mites. More before say 600. Times 5 because first off you killed the phoretic ones and you have a colony on the way to my problem child: 3,000 mites. Good luck. Which vaporiser do you use?

My wife bought me a varrox one for christmas last year but i made one out of a 12 volt water heater and a piece of metal for about a fiver lol and that works better than the varrox.

 

[Nige.Coll]

Isn't it a bit early to carry out OA vapourisation? At the recent LASI workshop they suggested that at higher ambient temperatures there was a marked increase in bee fatality (I have a memory of the figure of 10c being the top end of the range they'd treat in though I can't find the actual data from their study anywhere) as well as the obvious issue of capped brood.

I'm planning on treating using sublimation in December so would be very interested to hear of your experiences with doing it.

If you leave it too late the varrox type units don't penetrate the cluster so it doesn't work as well.

Hivemaker has said it all about losses i haven't noticed any problems in my limited experience.
the only thing now is the more hives you get the longer it takes. 12 or 13 mins a hive the instructions advise.

 

[TryingToLetThemBee]

My wife bought me a varrox one for christmas last year but i made one out of a 12 volt water heater and a piece of metal for about a fiver lol and that works better than the varrox.

Off to the workshop threads for me :- )

@sussexbaker; the rile of thumb is 20pct phoretic in the presence of sensible amounts of sealed brood

 

[Erichalfbee]

Have not noticed any bee or brood fatality at all, even with well over treating to see if there would be any, three treatments five days apart pretty much clears out most of the varroa.

Do you know, that seems a zillion times better than messing about with four weeks of suffocating thymol. What about queen mortality? Do you re~ queen every year? If you do then I suppose it doesn't matter.

 

[jenkinsbrynmair]

Having OMF floors and an underfloor entrance it may be wiser for me to build in a standalone floor with a built in vapouriser if I go down the sublimation route - move broodbox off floor onto vapouriser floor, do the deed, remove and move on to the next hive, hmmmmmmmm

 

[Hivemaker.]

Do you re~ queen every year? If you do then I suppose it doesn't matter.

No problems that i have noticed, no i don't re queen every year as a matter of course, only re queen those that need to be.

 

[sussexbaker]

Having OMF floors and an underfloor entrance it may be wiser for me to build in a standalone floor with a built in vapouriser if I go down the sublimation route - move broodbox off floor onto vapouriser floor, do the deed, remove and move on to the next hive, hmmmmmmmm

That strikes me as a really good idea. I'm using poly hives from Paynes so was concerned about melting the hives when I put the vapouriser into them. The solution I'd come up with was a mounting plate the same dimensions as the varroa monitoring board, with foam to seal each end. I'd then insert it under the OMF and let the vapours penetrate the hive that way. I like the idea of having a standalone floor for it though.

 

[itma]

…
@sussexbaker; the rile of thumb is 20pct phoretic in the presence of sensible amounts of sealed brood

It varies not only with the quantity of brood, but also with the quantity of brood relative to the varroa population and whether brood is increasing or decreasing, the proportion of drone brood, and likely lots of other variables.

With brood decreasing rapidly at present*, the phoretic proportion will be increasing towards its midwinter 100%. The minimum phoretic proportion is likely to be during spring colony expansion (following midwinter varroa treatment) with LOTS of brood cells and relatively few mites.



* Hivemaker has reported a regular end-of-summer (earlier than now) brood break on his colonies - providing him with the opportunity to apply an anti-phoretic treatment effectively. I'm not sure that is completely general throughout the country.

 

[Erichalfbee]

move broodbox off floor onto vapouriser floor, do the deed, remove and move on to the next hive, hmmmmmmmm

My problem would be the weight.

No problems that i have noticed.

Something to explore, then.
I have all my colonies on OMF and I'm sure not all the inspection trays provide a proper seal. I might go through all the floors as they come out of service to make sure they do.

 

[TryingToLetThemBee]

It varies.

Yes; that's why a rule of thumb (given a fair amount of brood) is useful. NBU uses 15 pct http://www.nationalbeeunit.com/downloadDocument.cfm?id=16 : I have seen higher. 20 pct seems useful. Any search for precision is not useful.