As I said in my first post on this subject and I thought that I had made it clear from the comparison with a fifty year old woman.
This is only my opinion and the result of observing things that happen in many years of bee breeding.  Yes, I do think that there is some sort of degeneration in the genetic material as time goes by - possible causes could include exposure to chemicals or radiation or just simply the effects of old age.  The genetic material of the queen might not be the only one affected - they are also carrying the sperm around with them.  I wouldn't expect either that the ova of an old queen (eg. 3-4years old) would be endowed with as much vigour as an ova from a 18-24 month old queen.  So, I repeat - the daughters raised from old queens are NEVER able to compare with the daughters of a queen in her prime.  Queens that are used for grafting from should also be held in a nucleus of not more than 4 frames.  If grafts are made from a queen in full lay in a large colony there are problems with vigour. 

Best regards
Roger White
Superbee Cyprus.

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