Closed Population Honeybee Breeding. 2. Comparative Methods of Stock Maintenance and Selective Breeding

Large, closed populations lose sex alleles more slowly than small ones, and are therefore better able to maintain acceptable levels of brood viability, and desirable genetic characteristics. The rate of loss of sex alleles can be decreased by selecting a single random-mated daughter replacement queen from each stock queen in each generation. An excess of heterozygous individuals can be obtained by subdividing the population and ensuring that cross-matings take place only between individuals belonging to different subpopulations. New sex alleles can be introduced into closed populations with a minimum of undesirable germ plasm only after adequate testing and identification of queens with new sex alleles. Selection for characters other than brood viability can accelerate the loss of sex alleles in a closed, random-mating population. However, concomitant selection for high brood viability may result in a decreased rate of loss of sex alleles, and consequently in a higher average brood viability in the population. Methods of breeding using closed honeybee populations, and their expected genetic consequences, are discussed.