The frequency of arrhenotoky in the normally thelytokous Apis mellifera capensis worker and the Clone reproductive parasite

Abstract

In most honey bees, unfertilized eggs develop into haploid males via arrhenotokous parthenogenesis. The Cape honey bee (Apis mellifera capensis) is different. Although mated queens always produce females sexually, if workers lay unfertilized eggs the eggs develop into diploid females via thelytokous parthenogenesis. Thelytoky in A. m. capensis has given rise to an entirely clonal lineage of reproductive parasites that infests colonies of their neighbouring subspecies A. m. scutellata. The switch from arrhenotoky to thelytokous worker reproduction is thought to be determined by a recessive allele at a single locus. However, it has recently been shown that this simple phenotype/genotype association may be more complex because individuals from the parasitic clonal lineage produce c.a. 15 % of eggs arrhenotokously and 85 % of eggs thelytokously. Here, we investigate the fate of these arrhenotokous eggs and show that they can develop into adult males. We further show that workers of the sexual A. m. capensis population produce far fewer arrhenotokous eggs. We discuss possible evolutionary explanations for this difference.