Document Type


Publication Date



Two types of parthenogenesis, arrhenotoky and thelytoky, exist in the Hymenoptera. Arrhenotoky, the development of males from unfertilized eggs, is present in all wasps and bees. Thelytoky, the development of diploid females from unfertilized eggs, is present in a few species. Two types of thelytoky, apomixis and automixis, are known. Most thelytokous Hymenoptera are automictic. No meiosis, only mitosis, occurs in apomixis. Meiosis does occur in automixis, allowing crossing-over and segregation of genes. Advantages of thelytoky are that heterotic combinations become fixed, gene loss is reduced, and reproduction requires only a single individual. One advantage of arrhenotoky is that genetic load in males is eliminated. Both environmental and genetic factors contribute to sex-determination in the haplodiploid system of Hymenoptera. Haplodiploidy can facilitate the evolution of social behavior. Parthenogenesis creates some taxonomic problems since thelytokous clones do not fit the generally accepted biological species concept. Some members of bisexual populations probablyacquire thelytoky, forming their own clones, races, or species.