Vaporising - how many times to treat?

[Jack Straw]

I have invested in a OA vaporiser and impressed with how quick and easy it is to use. I have downloaded the instructions from Varrox which suggest 1 treatment of 1mg is sufficient for a hive with a single brood box.

However I have also read a number of accounts (anecdotal not scientific) from people who treat three times with 5 days in between - obviously working on the assumption that the vapor does not kill the mites inside sealed cells.

These people are reporting fairly high drop rates on the second and third treatments which suggest it may be worthwhile and as the process it so quick and easy it makes sense to repeat if it is beneficial

Do other forum members treat 1,2, or 3 times. Has anyone found treating more than once has an adverse affect on the colony. Any comments would be welcome

 

[oliver90owner]

There are loads of threads on this subject, which I would ges are easy to search for.

Think a little about phoretic mite behaviour, or look up the life cycle of the mite, and along with all the info which tells you that oxalic does not kill mites in cells, you should be able towork out why and when multiple treatments are best.

 

[Jack Straw]

Thanks for your comment

There are loads of threads on this subject, which I would ges are easy to search for.

Think a little about phoretic mite behaviour, or look up the life cycle of the mite, and along with all the info which tells you that oxalic does not kill mites in cells, you should be able towork out why and when multiple treatments are best.

Thank you for your reply. I did think about mite behaviour and I was fine on that until I read the guide issued by Varrox.

If there is a mite fall of more than 1000 varroa mites
caused by the treatment, or if it is uncertain whether there
was brood in the colonies, a second treatment is recommended.
The optimal time for it, is two weeks after the first
treatment. If a second treatment is necessary only 1 gram
of oxalic acid has to be used, independent on the size of
the hive. Two or more treatments are very well tolerated
by the bees.
Source: Varrox guide ss 5.1
http://www.thorne.co.uk/image/data/Documents/GA_VARROX_2012_print.pdf

It just surprised me that if you are right when you say 'oxalic does not kill mites in cells' why Varrox reccomend a single treatment as the default

 

[TryingToLetThemBee]

Because it's like trickling; it's designed for a brood break. For those of us who do not reliably get MIDWINTER brood breaks (we seem to get an early-autumn one instead) eg Hivemaker, consensus has settled on 3 treatments 5 days apart POSSIBLY a fourth. It's 1g not 1mg, by the way.

I have done this on a number of colonies over the last 2 years with as yet no ill-effects

ADD "UK" as a location is pretty unhelpful to a discussion like this.

 

[EKBee]

I'm confused as to why 3 or 4 treatments are thought necessary?

If the female mite enters the cell on day 8 of the brood cycle just as the larvae is being capped over & the worker (as its winter & no drones) emerges day 21 that's 13 days later.

So these mites are hidden from the oxalic under the capped wax for 13 days
on day 13 (or so depending on temps) the bee emerges & the female mite will
live in its exposed phoretic stage for 4-13 days or so

If you hit them 14 days apart with the oxalic you should get the majority knocked down without need for further applications?

 

[TryingToLetThemBee]

I'm confused as to why 3 or 4 treatments are thought necessary?

If the female mite enters the cell on day 8 of the brood cycle just as the larvae is being capped over & the worker (as its winter & no drones) emerges day 21 that's 13 days later.

So these mites are hidden from the oxalic under the capped wax for 13 days
on day 13 (or so depending on temps) the bee emerges & the female mite will
live in its exposed phoretic stage for 4-13 days or so

If you hit them 14 days apart with the oxalic you should get the majority knocked down without need for further applications?

The question you are neglecting is how long you have lethal concentrations (say LD90) after treatment; it seems to be about 5 days so covering an entire cycle as you wish needs 3x5d. ADD Remember you have mites emerging and re-entering continuously.

 

[EKBee]

Thanks, dawned on me as soon as I posted, but I didn't know the crystals kill rate dropped off at 5 days I had in mind it was effective for 7 or so

 

[TryingToLetThemBee]

The way the 3x5 emerged over the obviously equally plausible 2x7 is that the extra dose was seen to be worth eliminating that doubt. Horses for courses really; no right way and any vape seems to give them a good knock.

As I have posted elsewhere I am a bit queasy about acidifying the hive so much but OTOH given there are many kg of honey etc in the hive the acidification is probably not that big of a deal and a good midwinter vape solves faffing around with formic acid in spring which I reckon seems to be much more aggressive. ADD (For, me no organophosphate acaricides etc is a given.)

 

[Jack Straw]

Thanks

The question you are neglecting is how long you have lethal concentrations (say LD90) after treatment; it seems to be about 5 days so covering an entire cycle as you wish needs 3x5d. ADD Remember you have mites emerging and re-entering continuously.

Thanks, that's the clearest explanation I've seen (and I've been trawling the web for the last few days). Appreciate you taking the time to post and give a clear rational summary.

 

[TryingToLetThemBee]

Thanks, that's the clearest explanation I've seen (and I've been trawling the web for the last few days). Appreciate you taking the time to post and give a clear rational summary.

Pleasure. And thanks for putting a location.

 

[linoleum bonypart]

Ive done 3 vapes per hive.... I think hivemaker tested a hive by over dosing and doing extra treatments to no detriment

 

[Erichalfbee]

And if you're getting large drops on all three vapes HM suggested a 4th four days after the third

 

[madasafish]

I stopped after one treatment. Hives were broodless and the drop averaged c30/hive..

 

[charlievictorbravo]

Here's a link to the latest UK research into Oxalic Acid treatments - http://www.tandfonline.com/doi/full/10.1080/00218839.2015.1106777

The critical difference between one treatment and 3 or 4 is whether or not there is brood in the hive. No brood - all the mites are phoretic and 97% can be killed with one treatment. Brood present - more than one treatment (usually 3, 5 days apart) so that mites are zapped in the phoretic stage between the in-cell parts of their life-cycles. If these treatments are too far apart, the female mite could emerge and re-enter another cell between treatments and escape unscathed.

CVB

 

[oliver90owner]

Ekbee is not thinking too clearly. The brood cycle is 23 days, which might easily stretch to 24 days (lets not assume this is an absolute figure). The beek needs to take into account the actual situation and treat appropriately.

Think here the instance of a very active colony. Would you not think that the residual oxalc might be virtually dispersed or cleaned out rather more quickly than for some other scenarios?

Beeks can either blindly follow these generic instructions, as dished out by the manufacturers, or do some sensible reasoning and thinking for themselves.

'Use by', 'best before', etc are axamples of this sort of thing. If an item had a shelf life of three days, one day over may be very important, but if the time from manufacture to expiry date is 6 months, or more, the risk of exceeding the 'use by' date by one day is much reduced. People need to use some common sense, if that is possible.

 

[JWF]

This year I did 3 vapes, 1st on day 1, 2nd on day 8 and the 3rd on day 22.

Drops were 250-300ish on the first two treatments, and next to nothing on the third.

Judging by cappings also on the board, my hives have had no significant brood break.

 

[Salamagundy]

Here's a link to the latest UK research into Oxalic Acid treatments - http://www.tandfonline.com/doi/full/10.1080/00218839.2015.1106777

CVB

Some advanced notice for those in Wales: Professor Francis Ratnieks (co-author of the paper quoted by CVB) will be giving two lectures in Llangadog on Sat., May 14th, hosted by East Carmarthenshire Beekeepers: (1) Research on Disease Control and (2) Understanding and Improving Bee Foraging. This is a non-profit-making event, so I hope it's ok to mention it here. All are welcome. Please PM me for further details.

 

[jenkinsbrynmair]

Some advanced notice for those in Wales: Professor Francis Ratnieks (co-author of the paper quoted by CVB) will be giving two lectures in Llangadog on Sat., May 14th, hosted by East Carmarthenshire Beekeepers: (1) Research on Disease Control and (2) Understanding and Improving Bee Foraging. This is a non-profit-making event, so I hope it's ok to mention it here. All are welcome. Please PM me for further details.

Keep me a seat - doesn't have to be near the front any more now my eyes are working again

 

[Millet]

And if you're getting large drops on all three vapes HM suggested a 4th four days after the third

Who is HM Erica.. is it some wild card copying the thymol treatment calendar but gassing instead.

 

[jenkinsbrynmair]

Who is HM .

Hive Maker ?