Gavin - thanks for posting that article. I have googled Nosema Ceranae to try and get more information, particularly regarding symptoms in a colony and treatment. It seems that it is generally considered to be a really serious problem. There is little advice on treatment but it has been suggested that the most effective control of Nosema Ceranae is the antibiotic fumagillin as recommended for Nosema apis. Is this a fancy name for Thymol or something different?

And nowhere could I find any colony symptoms other than a very rapid death. There may be diarrhoea as in Nosema Apis, but not necessarily so. Does anyone know more about this?