Scientific note updating allelic nomenclature standards of the highly diverse complementary sex-determiner locus in honey bees

Abstract

Honey bees rely on haplodiploidy for sex determination. Here, diploid eggs develop into females (i.e., queens and workers) and haploid eggs develop into males (i.e., drones). This system is regulated by complementary sex-determiner (csd)—a single, multi-allelic locus with very high diversity. Honey bees heterozygous at the csd locus will develop into females, while hemizygosity results in normal male development. Homozygosity at csd results in abnormal diploid males. Diploid males are usually destroyed by the workers early in development which can negatively impact the colony population, growth, and productivity. As such, maintaining genetic diversity at csd is critical for the health and productivity of honey bee populations. This is reflected in the increasing number of studies examining csd diversity in local and global populations. However, many csd alleles appear in multiple studies and have been assigned several different names, complicating cross-study comparisons. In 2020, we developed a standardized nomenclature for the hypervariable region (HVR) of honey bee csd alleles to facilitate a better understanding of csd diversity within and between populations. Here, we present an updated database including all csd sequences deposited into GenBank since our last publication. In only the last 4 years, 370 new csd sequences were deposited, including 154 novel HVR sequences.