Submitted to: Journal of Cryobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2021
Publication Date: 6/8/2021
Citation: Campion, C.C., Rajamohan, A., Rinehart, J.P. 2021. Comparative analysis of cryopreservation of seminal vesicle derived spermatozoa from Bombus impatiens and Apis mellifera - Implications for artificial insemination of bumble bees. Journal of Cryobiology. https://doi.org/10.1016/j.cryobiol.2021.06.002.
Interpretive Summary: Bumble bees are one of the world’s most important pollinators, including as pollinators for agriculturally important plants that cannot be pollinated by other insects. However, many bumble bee species are highly threatened and there is currently no protocol for the cryopreservation of their germplasm such as their eggs or sperm. This study reports the first successful cryopreservation and revival of bumble bee sperm cells. We compared the procedure on both honey bees and a domesticated species of bumble bee and found that 82% of honey bee sperm cells survived, while 55% of the bumble bee sperm cells remained viable. Although the bumble bee sperm survival was lower, it is still expected to be sufficient to artificially inseminate a queen bumble bee and obtain progeny. These findings will serve as a foundation for the development of protocols that will be essential to the safeguarding of important traits in domesticated species, and the preservation of threatened ones.
Technical Abstract: This study evaluates the efficacy of a cryopreservation protocol for the 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 an yolk-free non-activating buffer containing dimethyl sulphoxide and stored in liquid nitrogen for 24 hours 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. 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.