Effects of High and Low Glucose DMEM Extenders on Sperm Cryopreservation in Honey Bees

Abstract

Honey bee sperm can be stored and used at room temperature for up to a week. However, freezing storage methods used for long-term storage negatively affect the sensitive honey bee semen. In order to reduce this negative effect, many different diluents and various freezing protocols have been investigated. This study aims to evaluate the effect of Dulbeco's Modified Eagle Medium (DMEM) diluent with two different glucose concentrations on the spermatological parameters of frozen honeybee semen. The study used two different DMEM diluents containing high and low concentration of glucose. Honey bee sperm samples, diluted 13-fold with high glucose DMEM (4.5 g/L glucose, L glutamine and pyruvate) and low glucose DMEM (1 g/L glucose, L-glutamine and sodium bicarbonate) at a ratio of 1:12, were frozen in liquid nitrogen. For both groups, 10% (Dimethyl sulfoxide) DMSO was used as a cryoprotectant agent during freezing. After three months of storage at-196 degrees C, samples were thawed and sperm parameters were evaluated (sperm motility, viability, plasma membrane functional integrity, and morphology). Motility, viability, and plasma membrane functional integrity parameters were high in honeybee semen frozen with DMEM diluent with higher glucose content (P<0.001). In conclusion DMEM diluent with high glucose content can be used effectively in the cryopreservation of honey bee semen.