International audienceOlder larvae of honeybee drones are fed with a diet containing pollen. It is not known how pollen deprivation during the larval development of drones might affect their reproductive quality. This study investigated ejaculation ability and semen quality in drones reared in colonies with limited (LP) and unlimited (ULP) access to pollen. Access to pollen was limited by pollen traps. Drone brood rearing was not instantly abandoned in colonies with limited access to pollen. Colonies from the LP group reared drones with smaller mass, which ejaculated in fewer numbers and released smaller amounts of semen. The LP and ULP groups did not differ in semen quality as judged by the concentration, number, and viability of spermatozoa in ejaculate. It was found that access to pollen during larval development directly affects the reproductive quality of drones

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-We tested whether flow cytometry can be used for assessment of viability of honey bee (Apis mellifera) sperm. The method was used to detect possible competition between the sperm of different drones. The flow cytometry analysis of semen stained with SYBR-14/propidium iodide revealed significant differences between fresh and freeze-thawed samples. The identification of populations corresponding to viable and nonviable sperm allowed us to assess the sperm viability. The comparison of single-drone semen with mixed semen of two unrelated drones showed that sperm viability was not affected by mixing, but there were differences between mixed and unmixed semen in side scatter, which correlates with shape and optical homogeneity of particles. The proportion of particles in different populations also was affected by mixing of the semen. The results suggest that there are interactions between ejaculates of different drones, possibly related to sperm competition.honey bee / Apis mellifera / spermatozoa / sperm competition

S u m m a r yA comparison was done of the volume of semen and viability of spermatozoa collected from drones at ages 15, 20, 25 and 30 days. The drones originated from different queens and were reared in different environments. Semen volume was determined by measuring the filled length of a capillary. Percentages of live and dead spermatozoa were determined by SYBR-14/propidium iodide fluorescence staining and flow cytometry. The volume of semen collected from drones ranged from 0.5 to 1.3 µL. The mean volume of semen significantly decreased with drone age. Sperm viability increased significantly with drone age.

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