Effects of Spore Introduction and Ratio of Adult Bees to Brood on Chalkbrood Disease in Honeybee Colonies

SummaryThree groups of honeybee (Apis mellifera) colonies established on comb foundation were subjected to one of the following: (a) inoculation of the broodnest with a suspension of chalkbrood spores, (b) removal of some of the workers to decrease the ratio of adults to brood, (c) a combination of the two, while a fourth group served as untreated controls. All groups of treated colonies had significantly higher levels of chalkbrood than control colonies. The results indicated that at least two factors contribute to the development of chalkbrood disease in honeybee colonies: increased availability of the pathogen, Ascosphaera apis, and a decrease in the ratio of adult bees to brood.