COMPARATIVE EVALUATION OF TWO CRYOPRESERVATION PROTOCOLS
WITH PROGRAMMABLE FREEZING of
DRONE SEMEN

Introduction. The main purpose of the cryopreservation of drone semen is to make possible its use for the artificial insemination of queen bees to enable reproductive abilities on the same level as in bees inseminated by fresh semen. The most widespread methods for the cryopreservation of drone semen are freezing in liquid nitrogen vapor and programmable freezing. The most widespread form of cryopreservation for honeybee semen is using straws. However, the impact of liquid nitrogen on a sample in a straw is larger, as the surface area of the sample is increased. The purpose of this study is to comparatively assess both straws and cryovials in the programmable freezing of drone semen. Methods. The survival rate of spermatozoa was assessed according to overall motility and membrane integrity (viability) through a staining method using 1% eosin solution. Results. During the comparative analysis of the cryopreservation forms studied, it was revealed that cryovials are credibly superior to straws in programmable freezing at a rate of 1–3°/min, as shown by the overall motility (U = 3166.5 – 3637, p ˂ 0.05) and viability (U = 2786.5, p ˂ 0.05) of spermatozoa. The cryopreservation conditions influenced the quality of frozen-thawed semen. The overall motility of spermatozoa frozen in cryovials and straws at a rate of 1°/min was shown to be credibly higher in comparison with samples frozen at a rate of 3°/min (t = 2.3 and t = 2.9, p ˂ 0.05). Conclusion. As such, the cryopreservation of drone semen in cryovials has a manifest advantage over that using straws, in particular with a slower programmable freezing rate of 1°/min.