Personally, I'd just go with the syrup and not add any other concoctions. As far as vinegar goes, one of my bee books says it isn't good for bees. On one of the Yahoo groups not too long ago there was a discussion about adding Vitamin C. Some of those guys might have more to say on it. This is a little off your topic, but still might be pertinent. It talks about diseases:
"One official report said diseased bees were short of nitrogen, because their distended rectums contained much pollen. This followed the mistaken belief that adult bees usually did not need protein food and, when they did, that pollen was unsuitable; so it was recommended that all pollen combs should be removed in autumn and the colonies fed beef extract to make good their supposed nitrogen deficiency. This would certainly kill or seriously cripple any colony because pollen is essential for adult bees and beef exract is poisonous for them mainly because of its salt content. The ruinous idea of removing so called "pollen-clogged" combs persisted, however, and was widely practised fro many years." Leslie Bailey: 'Honey Bee Pathology'
"One official report said diseased bees were short of nitrogen, because their distended rectums contained much pollen. This followed the mistaken belief that adult bees usually did not need protein food and, when they did, that pollen was unsuitable; so it was recommended that all pollen combs should be removed in autumn and the colonies fed beef extract to make good their supposed nitrogen deficiency. This would certainly kill or seriously cripple any colony because pollen is essential for adult bees and beef exract is poisonous for them mainly because of its salt content. The ruinous idea of removing so called "pollen-clogged" combs persisted, however, and was widely practised fro many years." Leslie Bailey: 'Honey Bee Pathology'
