Sperm characteristics of Africanized honey bee ( Apis mellifera L.) drones during dry and wet seasons in the Caatinga biome

In this study, sperm from Africanized honey bee drones obtained during the dry and wet seasons of a semiarid region, the Caatinga biome, were characterized. The experiment was conducted during the peaks of the wet (March to June 2018) and dry (October to December 2018) seasons. Significantly higher cumulative rainfall was observed during the wet season (475.2 mm) in comparison to the dry season (27.6 mm). In each season, sperm from 50 Africanized honey bee (Apis mellifera L.) drones were obtained using the manual endophallus eversion technique and were evaluated in terms of the number of sperm per drone, motility, viability, morphology, and morphometry. The number of sperm per drone, the sperm motility, and the viability showed significantly better mean values during the wet season than in the dry season (3.8 ± 8.0 × 106 sperm/drone vs 3.0 ± 6.6 × 106 sperm/drone; 85.6 ± 8.5% vs 52.0 ± 2.9%; 82.8 ± 1.9% vs 70.9 ± 1.8%, respectively). A high incidence of sperm morphological defects (∼60%) was observed in both periods and was significantly more evident during the wet season. All morphometric parameters related to the length of the sperm head, tail, and total sperm were significantly higher during the wet season than during the dry season. In conclusion, honey bee drones present better sperm quality during the wet season than during the dry season in the Caatinga biome.