Long-Term Cooling (for a Year or More) the Sperm of Honey Bee Drones

The main purpose of preservation of drone sperm is to use such sperm for instrumental insemination of queen bees, which will reproduce many worker bees, as well as queens, do after natural mating. Preservation of honey bee drone sperm can occur through cryopreservation in liquid nitrogen and at temperatures above freezing. The use of antibiotic and antioxidant can reduce or prevent the microbial contamination of drone sperm during long-term storage at temperatures above freezing. The purpose of this study was to compare the viability, motility and fertility of undiluted sperm stored at a temperature of 3°C without antibiotics and antioxidants for a year or more. Undiluted semen was stored in sealed capillary tubes for 365 and 425 days. The survival of spermatozoa was assessed by total motility and by staining with 1% eosin. Preserved drone sperm after long-term storage in cooled form has an average viability of 53.7% (47.9–78%) and a total sperm motility of 14.1% (0–30%) on average. Virgin queen bees artificially inseminated with stored sperm laid fertile eggs. However, some of these fertile eggs hatched drone larvae. We found drone pupae that were located in worker cages with capped worker. The hypothesis is proposed that long-term storage at a temperature above freezing (3°C) can produce functional changes in drone spermatozoa. Some possible effects of these functional changes in spermatozoa may be hatched diploid drones.