Lonely female praying mantis

The only species of praying mantis that always reproduces asexually is the North American Brunneria borealis . All individuals of this species are females. The new study finds small genetic variations among them, indicating a relatively recent emergence of the species. Researchers believe that a single female praying mantis that could reproduce without a male may have become the ancestor of all representatives of this species in North America.

Parthenogenetic is the reproduction of organisms in which offspring appear without fertilization. An embryo is created when an unfertilized egg divides. Parthenogenesis most often occurs in invertebrate animals, but it has also been noted in some species of fish, amphibians, reptiles and birds. Sometimes in the life cycle of an animal, generations that reproduce parthenogenetically and generations that reproduce in the usual way alternate (facultative parthenogenesis). But for a number of species, parthenogenesis serves as the only form of reproduction, and males in these species do not exist at all.

Brunneria northern is found in grasslands along the Atlantic coast of the United States, from eastern Texas to central North Carolina. The species has been recorded in North Carolina, South Carolina, Georgia, Florida, Alabama, Louisiana, Mississippi, Arkansas, Oklahoma and Texas. The length of the insect can reach 7.7 cm. The wings of this species are small, and these mantises cannot fly.

While there are other praying mantises that reproduce parthenogenetically under certain circumstances, the fact that this is the only way Brunneria northern reproduces has intrigued scientists for decades. Another point in the reproduction of this species turned out to be unusual. While in most praying mantis species each larva emerges from its own opening in the ootheca and the larvae emerge simultaneously, the brunnerii ootheca has one small hole at the end, and the larvae emerge from there one at a time over several months.

Three biologists from Washington and Lee University in Lexington decided to study the praying mantis in detail. After catching enough specimens in the wild, they went to the laboratory where they performed DNA barcoding using a 610-bp region of the mitochondrial cytochrome oxidase I gene. The scientists found no changes in this genomic sequence in 24 mantises collected from nine sites in seven states. The researchers say this is unusual and suggest that mantises were introduced to North America relatively recently, with it likely that the American population was started by just one mantis. It is possible that a single female came to North America at the turn of the 20th century. Once she was ashore - all alone on a vast continent - she began parthenogenetic reproduction, and her offspring slowly moved across their North American range. The authors of the study indicate that northern Brunneria is the only representative of this genus in North America; other species - Brunneria brasiliensis , Brunneria gracilis , Brunneria grandis , Brunneria longa and Brunneria subaptera - live in South America. These species are characterized by facultative parthenogenesis. Scientists are paying attention to one population of Brunneria in Uruguay, the representatives of which are most similar to Brunneria north and may be its ancestors. Biologists intend to check this in their future studies.

The work was published in the journal Annals of the Entomological Society of America.