Genetic diversity of Apis melliferacomplementary sex determiner (csd) in four Australian breeding populations

Honey bee ( Apis mellifera ) breeding has intensified as populations experience increasing stress and pollination demand increases. Breeding programmes risk genetic diversity losses as mating is focused on a small group of individuals. Loss of diversity at the complementary sex determiner ( csd ) locus results in decreased viability and reduced honey production. Bees that are homozygous at csd become inviable males rather than workers. We examined csd diversity in four Australian breeding populations: a queen bee breeder from New South Wales, another from Queensland, a Western Australian breeding programme involving 11 bee breeders, and a research population at the NSW Department of Primary Industries. We found 82 unique csd alleles across the four populations, 16 of which have not been previously reported. This study provides a snapshot of csd diversity in Australia which will be useful for the national honey bee genetic improvement programme (Plan Bee).