Hi Tony,
 
        Please see my comments outlined in your text below:
 
 
In message <[log in to unmask]>, Tony Bloor <[log in to unmask]>
writes
>Hi
>
>I have recently tested my colonies for the presence of Varroa using
>Bayvarol strips, unfortunately, all four hives were infected. 48 hours
>after the strips were introduced the test trays showed a drop of 10, 10,
>6 and 52 dead mites respectively. I presume from these figures that at
>present this is a comparatively light infection.  24 hours later I
>examined the trays again, this time no mites were found. I reckon any
>infected larvae present, should emerge over the next fortnight, along
>with their unwanted guests!  As per the instructions, I will leave the
>strips in for the full six weeks, to catch the young mites as they leave
>the cells.  I intend to monitor the additional drops over the above
>period.  However, I have a couple of questions:
>
>Is it possible to estimate how many of the total adults are killed
>within that first 48 hours?
 
It depends on how many mites are there and how active the bee colony is,
how much capped brood you have at the time etc. Maybe Bayer will have
some estimated figure but I would say you cannoy judge the overall
efficacy of a treatment by the first 2 days mite fall. You should
however, get an indication of infestation.
 
 
> I was talking to a long standing beekeeper
>a few days ago who suggested virtually all of the emerged adults would
>be killed during this time.Over the next two weeks a majority of the, at
>present, capped mites will be eradicated as they emerge.
>
>Of the minority still present, after the fortnight, these presumably
>will be the ones exhibiting signs of resistance to Varroacides.
Why do you assume there are resistant mites? It's not automatic as a
result of chemical treatment; possible yes.
 
> Is the>effect of the chemical on these mites cumulative during the
following
>four weeks of treatment to the point where they can no longer tolerate
>its effect, or is length of exposure immaterial in these cases as they
>are resistant, period?
 
Resistance can be like a switch - it's either on or off. There may be
different levels of resistance within a population and then amount or
length of exposure to active ingredient will affect these individuals
differently. However, resistance will not increase during a treatment.
 
I also doubt that you are seeing resistant mites at this time in your
hive but you should inform CSL York (Mike Brown) if you are concerned
and they may be able to do a resistance test for you.
 
>I would like to consider trying Dr Rodriguez method of control, however
>in the UK the Government appears to be adamant that Bayvarol is the only
>legal chemical solution at present.
 
Not for long.
 
> So I may try drone trapping.
>
>Apologies for the length of the posting.
>
>
>Regards
>
>
>Tony
>Staffordshire, UK
 
--
Dr Max Watkins
Director
Vita (Europe) Limited