Willie says that his father and then initially he, bought in a load of Dutch, Belgian and particularly French bees I think- and he's mentioned that it's the French ones that gave been the basis for most of his amm traits, so, without Google give I'm not sure of the distinction between phenotype and halotype but I seem.to recall him suggesting that his 'amm' were genetically largely the same as the French black bee. Like I say though, ECT utterly wombled my memory so I could even have the roles of the Dutch and French bees conflated. He's a great raconteur if ever you get the chance- we see him with our local association a few times a year usually and should really organise another association trip to Chain Bridge for his reminiscences alone. I know a few years ago he experienced losses of between 1/3rd and 50% and drone virility is something he often bemoans with a theory that an awful lots of drones are infertile and those that aren't are negatively impacted by the pathogen load of one of the two types of DWV - a notion I'm sure David Evans has similarly espoused, and, utterly anecdotally, I've found my spring mated queens to be circa 75% less likely to turn drone layer the following spring compared to autumn matings, so I now try to get my breeding done early before the pathogen load vectored by varroa builds up too much