Instrumental insemination of Apis mellifera queens with hetero- and conspecific spermatozoa results in different sperm survival

Abstract

Sixty three queens of Apis mellifera were inseminated each with about 8 million spermatozoa from either 1 A. mellifera drone, 8 A. cerana, 5 A. dorsata or 20 A. florea drones. Spermatozoa were collected from vesiculae seminales, diluted in buffer and re-concentrated at 1,000 g for 10 minutes. Between 1.4% and 2.8% of the spermatozoa reached the spermatheca. Motility of spermatozoa of A. mellifera and A. cerana did not change within 4 weeks, it was nearly 100%. The motility of A. florea spermatozoa decreased to 83.4% after 3 days and to 33.9% after 4 weeks and motility of A. dorsata spermatozoa decreased to 61.2% after 3 days and to 26% after 4 weeks. Fertilization of A. mellifera eggs was 57% by A. mellifera spermatozoa. Calculation based on non-hatching eggs showed that about 40% were fertilized by A. cerana and A. florea and less than 20% by A. dorsata spermatozoa. The composition of spermathecal fluid seems to be different within the species and its significance for long term sperm storage is discussed.