A comparison of methods to experimentally induce chalk brood disease in honey bees

Abstract

Chalk brood in honey bee is a fungal brood disease caused by Ascosphaera apis. It is very difficult to reproduce chalk brood in a homogeneous way in a large number of colonies, therefore appropriate methods to experimentally induce and evaluate the disease would be useful for research. We inoculated experimentally the colonies, using three treatments: spores sprayed over combs, spores mixed with pollen and sugar syrup with spores. The collection of mummies in traps in the hive entrance, bottom board and combs showed a lack of efficacy in the quantification of the disease. A controlled chilling of the brood yielded very satisfactory results. Using this last technique, spores mixed with water sprayed over combs reached 90.63% of mummification, while colonies fed with spores mixed up with pollen reached 86.32%. The use of sugar syrup with spores (60.13% of mummification) proved to be less effective.