Thelytoky comes from the Greek thely, meaning "female", and tokos, meaning "birth". Thelytokous parthenogenesis is a type of parthenogenesis in which females are produced from unfertilized eggs. It is rare in the animal kingdom and has only been reported in about 1500 species.[1] It is more common in invertebrates, like arthropods, but can also occur in vertebrates, like some whiptail lizards. Thelytoky can occur by a number of different mechanisms each of which has a different impact on the level of homozygosity. It can be induced in Hymenoptera by the bacteria Wolbachia and Cardinium[2], and has also been described in several groups of Hymenoptera, including Cynipidae, Tenthredinidae, Aphelinidae, Ichneumonidae, Apidae and Formicidae.[3]
Hymenoptera (ants, bees and wasps) usually reproduce by arrhenotokous parthenogenesis. They have the haplodiploid sex-determination system, and usually unfertilized eggs develop into haploid males, and fertilized eggs develop into diploid females. In thelytoky, however, female workers or queens are produced by laying worker bees when diploidy is restored in their eggs by the fusion of two meiotic products.[4]. These laying workers are therefore producing unfertilized diploid eggs (with the full complement of 32 chromosomes). Thelytoky occurs in the Cape bee, Apis mellifera capensis, a strain of honey bee, and has been found in other strains at very low frequency. The diploid embryo that develops from the egg can develop into a worker bee or a queen bee depending on the amount of royal jelly the larva receives.