Antifungal activity of cymiazol salts against Ascosphaera apis

摘要

The activity of the cymiazol salts of oxalic and boric acids against Ascopharea apis fungi was examined. A method of synthesising eymiazol salts was elaborated. The pathogenic fungi were isolated from honeybees infected with chalk brood. Fungistatic and fungicidal properties of the salts were examined in vitro, though their efficacy was tested in vivo in the infected beehives of honeybee colonies. Although eymiazol oxalate showed a slightly higher inhibiting activity than borate (MIC = 0.008 mol/L and 0.012 mol/L, respectively), the latter is a definitely stronger fungicide (MFC > 0.032 mol/L for oxalate, as compared with 0.012-0.014 mol/L for borate). Used separately, none of these active ingredients (boric acid, oxalic acid, cymiazol) was effective as fungicide, exhibiting only fungistatic properties in tested concentrations. High fungicidal efficacy was displayed only by cymiazol borate. Studies on honeybee colonies confirmed the effectiveness of the salts of cymiazol in treating ascosphaeriosis. After 12-16 days of administering sugar syrup containing these preparations, either a considerable alleviation of the symptoms or even their complete abatement were observed. In families cured with a mixture of cymiazol oxalate and borate a complete abatement of symptoms was obtained. Cymiazol salts can be a valuable and safe supplement of fungicidal formulations used in apiculture.