Explain sex determination in bees.
In honeybees (or honey bees), sex is normally determined by the fertilization or non-fertilization of eggs, rather than the presence or absence of sex chromosomes. This mode of sex determination was first discovered by Johann Dzierzon, a Catholic priest, in 1845. Dzierzon reported that a virgin queen which has not taken a mating flight (the queens mate only while in free flight away from nest) produces only male progeny. His report was the first rigorous description of a sex determination system, occurring more than 50 years before the discovery of sex chromosomes. We now know that honey bees are not unique and that about 20% of animal species use a haplodiploid mode of reproduction. In haplodiploid systems, male progeny normally develops from unfertilized eggs, which are haploid and have just one set of chromosomes. The fertilized honey bee eggs, which are diploid and have two sets of chromosomes, differentiate into queens and worker bees.