At 08:31 AM 3/6/97 EST, you wrote:
>      [log in to unmask]
>REPLY TO RESISTANCE
 In my opinion ,Resistance is usually present in one form or another in
almost any gene pool but there can different manifistations of this
resistance-- For instance let's use us for a crude example-- if my skin is
exposed to formic acid I will react in direct proportion to the thickness of
my skin in the area exposed-- now we may have different skin thicknesses so
those of us that have the thickest skin will tend to survive longer and
propagate the species--such an individual may only exist in only 0ne to 1-2
millon. If one couples this with a behaviorial response where one has a
better ability to sense the acid and therefore moves away faster than others
--this too will increase the chances for survival.You can draw any number of
situations.
I believe that any organismcan adapt to almost ant situation over
time---therefore Apistan , formic acid or even breeding for resistance to
mites will ultimately be overcome with enough selection  . The trick is to
keep the selection pressure down by using different approaches.
 
Sorry for the lecture
 
>
>>   ...............  It is alleged that the mites cannot develop an
>>immunity to formic as they are doing to fluvalinate. Is this so and if so,
>>why?  I think that formic is a simpler compound than fluvalinate.  If you
>>don't know the answer, perhaps someone with a background in chemistry can
>>give us the answer.
>
>I certainly do not have a huge background in chemistry but I would like to
>add some comments especially for us beginners or hobbyists.  At a recent OBA
>meeting there was a researcher, Dr Nasr, discussing mite treatment with
>Formic acid as well as a representative from the manufacturer of Apistan.
> Both made it clear that mites can build up a resistance (or tolerance) to
>EITHER chemicals.  It was emphasized that ANY control (certainly any
>chemical control) can lead to resistance if it is used exclusively and
>continuously for long periods of time especially if during those periods the
>chemical concentration diminishes below the effective level.
>
>Thus it is desirable to have two (or more) alternate treatments used at
>DIFFERENT times.  The idea is that any natural selection during the use of a
>chemical is quite useless when the second is applied so we are controlling
>those more resistant to the other chemical as well as the general
>population.  Of course the mites might start a natural selection of
>resistance to the second chemical but that is then defeated when we apply
>the first chemical in the next cycle,
>
> Fortunately, the mechanism of these two, Formic acid and Apistan, are quite
>different and thus the mechanism of resistance or tolerance has to be quite
>different (i.e. the same change will not protect the mite from both).
>Apistan works by contact.  As the bees walk over the strip, the chemical
>adheres to their legs and is transferred to the mites.  It is effective in
>controlling Varroa but not trachea (if for no other reason that the tracheal
>mites are inside the bee and thus not contacted by the Apistan.
>Formic acid, on the other hand, controls by its fumes being breathed.  Both
>the bees and the mites breathe it but the mites are more susceptible thus
>the concentration level is critical.  It was stated that Formic acid
>controls both Tracheal and Varroa mites.  But, too low a concentration
>encourages natural selection by allowing mites with a slight resistance from
>breeding while destroying the general population.  If the concentration is
>too high the mites are destroyed but the bees are damaged or destroyed.
> Since the concentration in the beehive is a factor of temperature,
>ventilation, evaporation area etc. etc., one must be careful to follow
>recommendations and watch temperatures etc.
>
>The overall recommendation was to treat with formic acid in the spring
>during colony build up but before honey super are put on a ten day
>continuous treatment is recommended, this implies several visits for some
>pads that only work for 3 or 4 days or one visit if using an 8X10 inch pad
>of Homasote (tentest).  I have no experience with the Nassenheider pads but
>intend to learn and try.  (I seem to have missed the details of these.)
>In the fall, right after honey is taken off, it is recommended to treat with
>Apistan for the recommended 45 days.
>
>Thank you all for in depth discussions of the many areas.  It sure helps to
>solidify understanding.
>
>............. george fielder.
>
>
Dan Veilleux  Columbus, Ohio USA
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