> >>From what I understood, based on a study that OA > > miticide effect is mostly due to low pH solution > (and > > not from oxalate salts as originally expected)... > > Could you cite the study? Here is the link (copied and pasted from a post on the Belgian list): http://www.apis.admin.ch/host/varroa/udine.htm The > oxalic is diluted so > organic acids like vinegar should also work but some > do and some do not. As a small amateur beekeeper, I have not the full explanation. But, with regard to pH, it seems to me that most of organic acids are weak acids. Some acids constants : Oxalic : pKa1(25C)= 4.19 pKa2(25C)= 1.23 Acetic (vinegar) : pKa(25C)= 4.75 Formic (in solution) : pKa(20C)= 3.75 Oxalic is a diacid the second acidity is quite strong compared to most organic acids in solution. It could be compared with strong inorganic acids as sulfurous acid : pKa2(18C)= 1.81. Moreover, even if low pH is the main factor for oxalic acid according to the above link, it does not mean it is the same for others (weaker). > And why does a sugar solution of oxalic work better > than just water? It > appears something else is at work, not just contact. I would agree with you, but it would just be an "a priori". Last time I asked a reseacher for the OA mechanism of action on varroa, he answered to me he did not know while he was presenting a study comparing field results with OA and other products. So I guess the issue is still not clear. > Not unusual to have a lot of theorizing as to how > something works, but > this one seems counter to other observations. ??? I just tried to answere the original question (reporting hearings about similar observations) and tried to share information. The more people will share, the more I could progress, and respectively I hope. Respectfully, Hervé Découvrez le nouveau Yahoo! Mail : 250 Mo d'espace de stockage pour vos mails ! Créez votre Yahoo! Mail sur http://fr.mail.yahoo.com/ :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::