> >As I remember there are 18 known alternatives at the sex determination
> locus.


It depends upon the local population, Dick.  As I recall, researchers have
now identified over 50 sex alleles.


> >But there are things besides diploid drones that can cause shotgun
> patterns in worker brood.  I have seen it with EFB for instance.  At least
> I presume it was EFB even thou I could not see diseased larva as the
> problem went away totally as soon as I treated with antibiotics.


I observe exactly the same.  With close inspection, I've generally found
signs of EFB, but it sometimes takes close inspection of a number of brood
frames.


> > My bees are pretty hygienic and I think often clean out diseased larva
> before the larva show visible symptoms.


I came to the same tentative conclusion.

Another cause of poor larval survival and spotty brood is poor nutrition.
Either not enough pollen coming in, or pollen of incomplete protein or
other nutrient balance.  In such case, workers will follow behind the queen
and consume eggs and young larvae rather than attempting to feed them.

And of course, do not ignore the possibility of exposure to fungicides or
other environmental toxin.


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

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