PROPERTIES OF HONEYBEE LARVAE KILLED BY CHALKBROOD DISEASE

Dried remains (mummies) of chalkbrood-killed larvae contain much less glycogen than healthy larvae or larvae killed by American foulbrood (AFB) disease [Bacillus larvae]. The mummies are depleted of glucose. They also lack many sulphydryl-containing compounds present in healthy and AFB-killed larvae. Growing cultures of the pathogen, Ascosphaera apis, possess phosphatase but lack other enzymes found in many pathogenic microorganisms. Growth of A. apis cultures in yeast-starch medium was stimulated by simple sugars and trehalose. No detectable acid was produced from any of the sugars, and the pH of the chalkbrood mummies was higher than that of AFB-killed larvae. A. apis is a relatively non-invasive parasite that kills the host by competition for primary nutrients.