Storage Conditions of Sperm Samples and Gametic Characterization by Sperm Head Morphometry in Drones (Apis mellifera)

The present study aimed to evaluate an optimal method to transport and store drone sperm samples, as well as to characterize drone spermatozoa through sperm head morphometry. A total of 291 mature drones were used. We performed three experiments. In a first experiment, sperm variables were assessed under different incubation conditions (5 °C, 15 °C, and 37 °C with 5% CO₂). Results showed that sperm viability was optimally maintained at 15 °C (p ˂ 0.05). In the second experiment, the supplementation of extender with catalase (200 UI) improved (p ˂ 0.05) the sperm viability and motility during liquid storage at different incubation times. Finally, a morphometric analysis of sperm head was made: length 5.13 µm, width 0.85 µm, area 3.78 µm², perimeter 15.01 µm, acrosome length 3.50 µm. The variability in sperm head morphometry was calculated by coefficients of variation (CV) within- and between-drones. The CV within-drone was higher than the CV between-drones for all morphometric parameters regardless of hive origin, indicating a high degree of sperm pleomorphism.