Effects of age, season and genetics on semen and sperm production in Apis mellifera drones

Adult drone honey bees from 4 Australian breeding lines were reared under similar conditions and examined for semen and sperm production when 14, 21 and 35 days old, during spring, summer and autumn. Almost half (40.5%) of all drones examined did not release any semen when manually everted. For those that released semen, the average volume released per drone was 1.09 μL (range 0.72 (±0.04)−1.12 (±0.04) μL) and the average number of sperms in the semen per drone was 3.63 × 10 6 (range 1.88 (±0.14)−4.11 (±0.17) × 10 6 ). The release of semen was dependent on breeding line and age ( P < 0.05), but not on the rearing season. The volume of semen released per drone was dependent on season, age, and breeding line ( P < 0.05), while the concentration of sperm in the semen was dependent on season and breeding line ( P < 0.05). Hence our data indicate that genetics underpins the maturation of drone honey bees as well as the volume of semen they release and the concentration of sperm in that semen.