For the first time, scientists have genetically engineered fruit flies to undergo parthenogenesis, also known as virgin birth or asexual reproduction. The research, published in Current Biology, marks the first time researchers have demonstrated the ability to genetically induce this form of reproduction in an animal that normally reproduces sexually. After asexual reproduction was induced, the ability was inherited by subsequent generations. The findings provide valuable insights into the genetics of asexual reproduction and are of special interest to researchers studying crop pest reproduction.
Virgin Birth: Nature’s Astonishing Anomaly
In the natural world, the predominant mode of reproduction is sexual, where a female’s egg combines with a male’s sperm to create offspring. However, parthenogenesis defies this norm. It is the process by which an egg develops into an embryo without the need for fertilization by sperm, rendering males obsolete in the reproductive equation. Offspring from this process are not exact clones of their mothers but are always female and very similar, genetically.
Gene Sequencing Holds the Key
The researchers began their investigation by examining a species of fruit fly known as Drosophila mercatorum, which is capable of parthenogenesis. By sequencing the fly’s genome, they pinpointed the specific gene responsible for this unique reproductive mechanism. The researchers were then able to transfer this capability to another species of fruit fly, Drosophila melanogaster, which typically reproduces through sexual means.
The key achievement of the study was the successful modification of the D. melanogaster gene to trigger virgin births. This alteration allowed the genetically manipulated female flies to initiate asexual reproduction. However, they only did so when males were not available, suggesting the switch could be used as a tool to allow a species to survive.
The researchers found that only 1 to 2 percent of the second generation of female flies with the ability for virgin birth produced offspring, and only when there were no male flies around. Alexis Sperling, a researcher at the University of Cambridge and the paper’s first author, noted in a statement, “In our genetically manipulated flies, the females waited to find a male for half their lives — about 40 days — but then gave up and proceeded to have a virgin birth.” The resulting offspring of these genetically modified flies displayed the ability to reproduce either through conventional mating with males or by means of virgin births.
Implications for Pest Management
“It was truly stunning for us to find how tripping a small number of genetic switches would enable virgin Drosophila melanogaster fruit flies to generate viable and fertile offspring just like virgins of their distant Drosophila mercatorum cousins,” said David Glover, senior author and research professor of biology and biological engineering at the California University of Technology in a statement. “It will be important to understand the generality of this ability, since many crop pests are able to reproduce in an asexual manner.”
Sperling will look for ways to apply the research findings to efforts aimed at curbing crop pests in her work at the University of Cambridge’s Crop Science Centre. One research area will examine why virgin birth in insects may be increasing, especially in pest species. “If there’s continued selection pressure for virgin births in insect pests, which there seems to be, it will eventually lead to them reproducing only in this way. It could become a real problem for agriculture because females produce only females, so their ability to spread doubles,” she said.
Regardless of future applications, the research provides insight into insect reproduction and marks the first time that scientists have been able to genetically induce asexual reproduction in insects and demonstrate that subsequent generations inherit this characteristic.
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