A new fluorescent method to determine honey bee sperm motility parameters with computer-aided sperm analysis

Abstract

Honey bees are a keystone species, playing an important role in the food cycle. Improving honey bee reproduction will aid in the replacement of lost colonies. Fertility potential and reproductive health are dependent on semen and sperm quality. Current data on drone semen parameters are limited to semen volume, sperm concentration, sperm viability, and the assignment of sperm motility grade scores. The assessment of drone sperm motility is of importance to determine fertility potential and colony health. This study aimed to establish a quantitative and a qualitative method to measure drone sperm quality, and the fertility potential of Apis mellifera capensis subspecies of South Africa. Firstly, an improved five-point semi-quantitative manual motility index score was used to classify drone sperm motility. Secondly, it was possible to accurately analyse drone sperm motility qualitatively using a fluorescent technique in conjunction with a computer-aided sperm analysis (CASA) system. Manual motility index scores corresponded with total motility percentages as determined by using a CASA system. Furthermore, low values for motility kinematic parameters, particularly velocity parameters, were obtained in samples with both low motility index scores and low total motility percentages. Additionally, total sperm motility percentage and velocity parameters positively correlated with sperm total progressivity. This study provides in-depth data on honey bee drone sperm motility and motility kinematic parameters, which can serve as a reference for future studies on honey bee sperm and possibly related species.