Factors affecting the successful cryopreservation of honey bee (Apis mellifera) spermatozoa

This report is about cryopreservation of honey bee semen. There has been little advancement of this technology over the past 20 years. Cytotoxicity of the cryoprotectants, temperature sensitivity, freezing rate, and cold shock were investigated. The least toxic cryoprotectant was DMSO. Spermatozoa were tolerant to temperatures up to 40 degrees C. A programmable freezing rate of 3 degrees C/min proved superior in most treatments when compared to a freezing rate of approximately 28 000 degrees C/ min. Highest viability of spermatozoa (93%) post cryopreservation resulted from the treatment containing a 10% DMSO diluent, slow cooled to just above freezing, and frozen at a rate of 3 degrees C/min. Spermatozoa frozen in such a manner yielded viability and motility indistinguishable from that of unfrozen semen. Promising results warrant a field study.