Inheritance of thelytoky in the honey bee Apis mellifera capensis

Abstract

Asexual reproduction via thelytokous parthenogenesis is widespread in the Hymenoptera, but its genetic underpinnings have been described only twice. In the wasp Lysiphlebus fabarum and the Cape honey bee Apis mellifera capensis the origin of thelytoky have each been traced to a single recessive locus. In the Cape honey bee it has been argued that thelytoky (th) controls the thelytoky phenotype and that a deletion of 9bp in the flanking intron downstream of exon 5 (tae) of the gemini gene switches parthenogenesis from arrhenotoky to thelytoky. To further explore the mode of inheritance of thelytoky we generated reciprocal backcrosses between thelytokous A. m. capensis and the arrhenotokous A. m. scutellata. Ten genetic markers were used to identify 108 thelytokously-produced offspring and 225 arrhenotokously-produced offspring from 14 colonies. Patterns of appearance of thelytokous parthenogenesis were inconsistent with a single locus, either th or tae, controlling thelytoky. We further show that the 9bp deletion is present in the arrhenotokous A. m. scutellata population in South Africa, in A. m. intermissa in Morocco and in Africanized bees from Brazil and Texas, where thelytoky has not been reported. Thus the 9bp deletion cannot be the cause of thelytoky. Further, we found two novel tae alleles. One contains the previously described 9bp deletion and an additional deletion of 7bp nearby. The second carries a single base insertion with respect to wildtype. Our data are consistent with the putative th locus increasing reproductive capacity.