Effects of cryopreservation on Bombus impatiens spermatozoa

Bumblebee populations are increasingly under threat from urban and rural landscape changes, pesticides and pathogens, and climate change. Declines in population abundance and in spatial distribution has led to endangered species listing or petitions for multiple bumble bee species (e.g. B. affinis, B. terricola, B. occidentalis). Cryopreservation of genetic resources to conserve germplasm can provide insurance against species loss. Attempts to store honey bee germplasm, especially by semen cryopreservation, have been successful but such techniques are not available for other important pollinators like bumble bees. As a first step to cryopreservation of germplasm in bumble bees, we evaluated the efficacy of a standardized protocol previously used for Apis mellifera using Bombus impatiens testicular and seminal vesicle derived semen. The semen was frozen and stored in liquid nitrogen for 24-72 hours using a non-activating buffer containing dimethyl sulphoxide. Thereafter, the frozen germplasm samples were thawed rapidly and assessed using the live-dead differentiating fluorescent dyes, Sybr® 14 / Propidium iodide. Semen viability in cryopreserved samples (86.0 ± 3.01 %) was not statistically different from controls (83.9 ± 7.1 %), suggesting that this approach may allow for cryopreservation of germplasm in bumblebees. Further studies are being carried out to assess DNA stability and feasibility of artificial insemination in Bombus.