>> 3. I wonder why Varroa has variability for a character like
>>fluvalenate
>> resistance anyways ?  Why do alelles that confer fluvalenat
>>resistance
>> exist in natural Varroa populations...?...
 
>What about mutation?  There are, I assume, billions upon billions of >mites
>under pressure from fluvalinate.  Any sucessful mutations would soon
>dominate.
 
>Allen
 
Insect resistance to pesticides is not the results of mutation. If an
given specie of insect is poisened by a pesticide they will not
transform themselves (mutate) to be resistant to that substance.
Pesticide resistance of a specie is the result of a more or less small
proportion of the population: Of the billions of individuals that form a
specie there are always some that are slightly different as a result of
errors in the replication of their genetic code. As a result there is
always a small proportion of the bugs that will  survive to the
pesticide and since they are the only survivors able to reproduce they
will transmit this resistance to their descendants and soon populations
of the pest will be back to normal or even cause problems worse than
before. Integrated pest management is compulsery unless we want to
introduce more and more pesticides in our environment. And remember that
toxicity tests of a substance is based on relatively short term and that
the action on humans of bio-accumulation of many years of exposure is
almost impossible to determine for economic reasons but also because we
are exposed to many other substances and it is therefore impossible to
associated an illness to a particular substance.
We have to find intelligent solutions, like the one promoted by Dr.
Rodriguez. They are often more trouble than to use commercially
available pesticides but, and nobody can tell, maybe you wont die of
cancer in 20 years or so as a result of pesticide usage.