Genetic differentiation in the queen breeding population of the western United States

Abstract - Commercial honey bee queens in the United States are produced primarily in two geographically separated regions, one in the southeastern US and the other in central California. We used mitochondrial DNA and allozyme variation to characterize 178 breeder queen colonies from 22 California apiaries. Two colonies had the mtDNA haplotype characteristic of Apis mellifera mellifera, the first subspecies known to be introduced to the US, and 176 had the haplotype associated with A m carnica and A m ligustica, the most popular commercially available subspecies. Malate dehydrogenase (Mdh) allele frequencies for the western population, Mdh⁶⁵ = 0.65, Mdh ⁸⁰ = 0.09 and Mdh¹⁰⁰ = 0.26, were significantly different from those previously reported for feral and southeastern commercial populations. Among the California samples, bees described by apiarists as 'Italian' or 'Carniolan' were significantly different from each other based on Mdh allele frequencies. Five other enzymes known to be polymorphic in honey bees were invariant in the California samples. Differentiation between populations in the United States suggests they may act as reservoirs for genes that can be useful for bee breeding programs.