Detection and thermal destruction of the chalkbrood fungus (Ascosphaera apis) in honey
Denis Anderson; Helen Giacon; Nicole Gibson
A sensitive culture technique for detecting viable spores and mycelial elements of the chalkbrood fungus, Ascosphaera apis, is described. The technique involves embedding honey or distilled water containing A. apis spores or mycelial elements in 15 ml of sterile liquid nutrient agar medium (10 g yeast, 10 g glucose, 13.5 g KH2PO4, 10 g soluble starch and 20 g agar) cooled to 60°C. This medium is then poured on a 7-ml layer of similar but solid agar medium in a standard 8.5-cm petri dish and allowed to solidify by cooling. The medium is incubated in an anaerobic environment at 37°C for 24 h, and then incubated in an aerobic environment for up to 9 days at 37°C. It is examined daily for A. apis growth. The technique facilitated the detection of viable A. apis in honey and was used to show that many pre-packaged retail honeys contain viable A. apis. The technique was also used to show that honey may be rendered free of viable A. apis by holding it in water baths at 65°C for 8 hours or at 70°C for 2 hours.