Effect of Flowering Period on Drone Reproductive Parameters (Apis mellifera L.)

Abstract

Insufficient protein intake during the larval phase of drones affects the development of reproductive organs and spermatogenesis. The aim of the study was to evaluate the effect of the flowering-scarcity and flowering-onset periods on the eversion of the copulatory apparatus, ejaculation, and sperm quality of drones (Apis mellifera L.). To stimulate the laying of drone eggs during the flowering-scarcity period, 1 L of sugar syrup was supplied weekly to the hives, along with a protein supplement made of 20% pollen and 80% brewer’s yeast. During the periods of flowering scarcity and the onset of flowering, 800 drones were collected (200 per month). At the onset of flowering, 270 drones showed eversion of the copulatory apparatus, of which 162 ejaculated, compared to the flowering-scarcity period, where 112 drones showed eversion of the copulatory apparatus and 39 drones ejaculated. During the period of flowering onset, sperm parameters such as volume, concentration, motility, viability, acrosome integrity, and mitochondrial activity were higher compared to the period of flowering scarcity. In conclusion, we observed a greater number of drones with eversion of the copulatory apparatus and ejaculation, as well as better sperm quality with the drones bred during the period of flowering onset. These differences indicate that the flowering-scarcity period significantly impacts the reproductive parameters of drones.