Long-term storage of Ascosphaera aggregata and Ascosphaera apis, pathogens of the leafcutting bee (Megachile rotundata) and the honey bee (Apis mellifera)

Survival rates of Ascosphaera aggregata and Ascosphaera apis over the course of a year were tested using different storage treatments. For spores, the storage methods tested were freeze–drying and ultra-low temperatures, and for hyphae, freeze–drying, agar slants, and two methods of ultra-low temperatures. Spores of A. aggregata and A. apis stored well at −80 °C and after freeze–drying. A. aggregata hyphae did not store well under any of the methods tested while A. apis hyphae survived well using cryopreservation. Spores produced from cryopreserved A. apis hyphae were infective. Long-term storage of these two important fungal bee diseases is thus possible.