On Tue, 7 Jul 2009 10:22:48 -0500, Bob Harrison <[log in to unmask]> wrote:

> However the effect on the colony (other than the above) has been found to be very slight.

Developing queens in colonies treated with as little as one coumaphos-impregnated strip for more 
than 24 h suffered a high mortality rate. Several of the queens showed sublethal effects from the 
coumaphos, including physical abnormalities and atypical behavior. The queens exposed to 
coumaphos weighed significantly less and had lower ovary weights than the control group queens. 
The highest coumaphos concentrations were observed in the queen cells and wax of the high-dose 
groups.

Journal of Economic Entomology 95(1):28-35. 2002

More recent information:

The results of this study clearly show that coumaphos
should not be used in colonies where drones are
produced. Compared with controls and other miticide
treatments sperm viability of drones exposed to coumaphos
was significantly lower initially and continued
the trend through the 6-wk sampling period. It is
possible that extreme viability decreases observed in
spermatozoa stored from coumaphos exposed drones
could affect the performance of queens if mated with
these drones. Queen performance could drastically
decline 6 wk after insemination or mating, leading to
queen failure, and thus partially explain the current
problems associated with maintaining productive
queens in colonies.

J. Econ. Entomol. 101(4): 1081-1087. 2008

[OK, so now I have a stack of papers on my desk that show that imidacloprid doesn't harm bees and 
another stack that show that miticides do.  Yet some folks still insist that imid wipes out hives but 
miticides don't. The loss of queens 6 after six weeks or even six months, is not a trivial affair, unless 
you are getting them for free. What value is there in ponying up $20 or more for mite resistant 
stock, if they only last half a year and then get replaced with who-knows-what? You may not be 
using Checkmite but does your queen breeder? pb]

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