> >Do we know for certain that evolutionary change is responsible for the
> diminished reports of tracheal mite infestation or is it possible that the
> persistent use of acaricides in our efforts to irradicate varroa are
> providing a beneficial side effect?


Shortly after the arrival of tracheal mite in California, after it wiped
out 70% of our colonies, Steve Taber started selecting for colonies that
exhibited resistance.  In a few years he release the line as breeder
queens.  I purchased some and started breeding from them, with amazing (at
the time results).  No more tracheal mite winter kills.  This was without
the use of varroacides, since varroa had not yet arrived.

Since no breeders breed from deadouts, there was strong selective pressure
towards tracheal mite resistance, and soon no one that I knew was treating
for tracheal mite any more.  I've still got a large box of menthol crystals
in the back of the barn.

Today, as Pete points out, applications of some varroacides likely keeps
tracheal mite pops down.  However, according to research by Dr Eric Mussen,
amitraz was not effective against T mite.  Amitraz has been the main or
only miticide in many commercial operations for some time, so I'm not clear
as to whether it has much to to with T mite.

>Whether this is evolution or not is a semantic issue. It may lead to
evolutionary change and adaptation in populations, but if it's just
revealing traits that were already there, then no real change has occurred
-- just a demographic shift.

Pete, perhaps for the sake of discussions on Bee-L we should agree on the
definition of evolution.  If you want it to solely apply to the
introduction of new alleles or entire genes, then perhaps you should
specify mutant-based evolution.

All humans share 100% of their genes, yet there are stark differences
between Inuits adapted to the Arctic, Rwanda pygmies, tall Dinka, or
lily-white Norwegians.  Hard for me not to call that evolution.

The fact is that the simple rearrangement or up or down regulation of many
conserved genes suffices for much evolution.  I snipped the table below to
illustrate the point.  Some authors, by including ALL genes (not just those
coding for proteins) come up with higher figures.

*What percent of their genes match yours?*
Another human? 100% - All humans have the same genes, but some of these
genes contain sequence differences that make each person unique.
A chimpanzee? 98% - Chimpanzees are the closest living species to humans.
A mouse? 92% - All mammals are quite similar genetically.
A fruit fly? 44% - Studies of fruit flies have shown how shared genes
govern the growth and structure of both insects and mammals.
Yeast? 26% - Yeasts are single-celled organisms, but they have many
housekeeping genes that are the same as the genes in humans, such as those
that enable energy to be derived from the breakdown of sugars.
A weed (thale cress)? 18% - Plants have many metabolic differences from
humans. For example, they use sunlight to convert carbon dioxide gas to
sugars. But they also have similarities in their housekeeping genes.



-- 
Randy Oliver
Grass Valley, CA
www.ScientificBeekeeping.com

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html