Occurrence and distribution of Ascosphaera apis in North America: chalkbrood in feral honey bee colonies that had been in isolation on Santa Cruz Island, California for over 110 years

Twenty strains of Ascosphaera apis were cultured from larval mummies and discolored larvae from feral honey bee colonies that had been in isolation on Santa Cruz Island, California for over 110 years, long before chalkbrood was first reported from the USA in 1968. Disease symptoms and enzyme patterns of A apis differed from those found on the mainland. Island strains showed little variability. These results and the history of the bees suggest that the pathogen accompanied the bees to the island and that the bees survived chalkbrood by a combination of hygienic behavior and microorganisms that inhibit A apis which were isolated from larvae and stored pollen