IN VITRO EVALUATION OF THE EFFECTS OF ESSENTIAL OILS ON ASCOSPHAERA APIS, THE CAUSATIVE AGENT OF CHALKBROOD DISEASE

Апстракт

Honeybee diseases cause considerable expenses to beekeepers for cost of maintaining apiary’s inspection, colonies damaged or destroyed and drugs fed to prevent bee’s infections. One of them is Ascosphaera apis, a fungal pathogen causing Chalkbrood disease in honey bee larvae. Chalkbrood is most frequent during damp conditions. Infected larvae turn chalky white color, become hard, andthen  turn black. It can be regarded as “the most widespread infectious disease” and this has led toecon omic loss in apiculture. We aim to find an alternative approach by using essential oils frommedicinal plan ts in combating and controlling the disease. Therefore, current article compiled the effects of ten essential oils (citral, geraniol, citronelol, cinamaldehid, thymol, eucalyptus oil, lemongrass oil, fennel oil, clove oil and cedar oil) on Ascosphaera apis in the laboratory with an agar diffusion method and the method of serial dilutions in microdilution plate. A. apis strains were
isolated from the dead honey bee larvae and the fungal strains were identified using a lightmi croscopy. Various concentrations (0.08% - 10%) of the essential oils were experimented fordetermin ation of minimal fungistatic and also fungicide concentration. After incubation, the zones ofinhibition were deter mined with a magnifying lens. The minimal inhibitory concentration was in range of 0.3125% - 1.25% for tested essential oils (MIC- values), and the minimal fungicide concentration was in range of 1.25% - 5%. All tested substances shows in vitro fungistatic and fungicide potential and can be considered as potential alternative active agents for prevention and control of chalkbrood disease without the use of antibiotics.