Insemination of honey bee, Apis mellifera, queens with non-frozen stored semen: sperm concentration measured with a spectrophotometer

SUMMARY

Non-frozen storage of honey bee semen is one possible method to preserve this species' germplasm, as honey bee queens naturally store sperm for years at brood nest temperatures. In the past, most work has used cell counting chambers and small repeated samples to assess the number of sperm stored in a queen's spermatheca. To calibrate a spectrophotometer to measure sperm concentration using the entire contents of the spermatheca, five groups of queens—virgins, naturally mated, or inseminated with one, four or eight μl of semen—were assayed. Absorbance at 260 nm and 550 nm gave measures that were significantly correlated with direct cell counts using a counting chamber. Although the viability (percentage of live sperm) was high for semen stored at room temperature for eight weeks, a second population of queens inseminated with semen stored for four weeks or longer had reduced concentrations of sperm in the spermatheca. The area and quality (drones in worker cells) of brood from queens inseminated with fresh and two-week old semen were similar, but there was a trend toward reduced brood area and increased drone laying in queens receiving semen stored over four weeks.

Keywords:

• honey bees
• Apis mellifera
• queens
• spermatozoa
• viability
• germplasm
• spectrophotometer
• turbidity
• sperm concentration
• spermatheca
• storage