Cryopreservation of seminal vesicle derived spermatozoa from Bombus impatiens and Apis mellifera - Implications for artificial insemination of bumble bees.

This study evaluates the efficacy of a cryopreservation protocol for spermatozoa derived from the accessory testis of male Bombus impatiens. It is also the first report of successful cryopreservation of bumble bee spermatozoa. The spermatozoa viability was compared with the similarly treated honey bee spermatozoa derived from its accessory testis. The semen was frozen using a yolk-free non-activating buffer containing dimethyl sulphoxide and stored in liquid nitrogen for 24 h to ~14 days. Thereafter, the frozen samples were thawed rapidly and assessed by staining with live/dead differentiating fluorescent dyes. Semen viability in cryopreserved samples (55.8 ± 14.0%) was significantly different than controls (96.2 ± 10.5%). Similar assessment with A. mellifera resulted in 82.2 ± 7.0% viable cryopreserved spermatozoa versus 99.4 ± 0.1% in controls. A similar proportion of the sperm cells were also capable of motility upon dilution of the extender medium with phosphate buffered saline. The proportion of viable accessory testis derived sperm cells obtained post-cryopreservation was estimated to be sufficient to initiate long term storage and artificial insemination programs.