Scientists induce virgin birth in fruit fly for first time

Scientists have achieved a groundbreaking feat by inducing virgin birth in the fruit fly Drosophila melanogaster, a species that typically reproduces sexually. This ability can be inherited across generations, allowing the offspring to reproduce either sexually with males present or through virgin birth without male involvement. In most animals, reproduction is sexual, but virgin birth, or “parthenogenesis,” enables embryos to develop without fertilization by sperm, eliminating the need for males in the process. Although the offspring are not exact clones of their mother, they are genetically very similar and always female. The researchers, led by Dr. Alexis Sperling from the University of Cambridge, successfully engineered these virgin births, marking a remarkable achievement in the field. The genetically modified female flies waited for around 40 days to find a male, but eventually, they gave up and proceeded to have a virgin birth. This discovery opens up new avenues for understanding reproduction in various species.

One strain of this fly reproduces only through virgin birth. Credit: Jose Casal and Peter Lawrence

In a groundbreaking study published in the journal Current Biology, researchers have achieved virgin birth in the fruit fly Drosophila melanogaster, a species known for sexual reproduction. They found that around 1-2% of the second generation of female flies with the ability for virgin birth were able to produce offspring, but only in the absence of male flies. When male flies were present, the females mated and reproduced in the usual way.

The ability for virgin birth can serve as a survival strategy, enabling a one-off generation to sustain the species. To achieve these results, scientists first analyzed the genomes of two strains of a different fruit fly species, Drosophila mercatorum, where one strain reproduces only through virgin birth. They identified the specific genes involved in this process.

With the candidate genes for virgin birth ability identified in Drosophila mercatorum, the researchers then modified the corresponding genes in Drosophila melanogaster. This successful alteration granted Drosophila melanogaster the ability for virgin birth.

The research involved an extensive experiment with over 220,000 virgin fruit flies and spanned six years to complete. This groundbreaking discovery sheds light on the mechanisms of reproduction and opens up new possibilities for understanding and manipulating the reproductive processes in various species.

Dr Sperling (at left) in the lab with a student. Credit: University of Cambridge

The key to this groundbreaking discovery lies in conducting the research in Drosophila melanogaster, a fruit fly species that has been a long-standing “model organism” in genetics research for over a century. The extensive understanding of its genes made it uniquely suitable for this study, which would have been exceptionally challenging in any other animal.

Dr. Alexis Sperling, who conducted this research in the Department of Genetics, has since moved to the Cambridge Crop Science Centre to focus on crop pests. She aims to explore why virgin birth in insects may be increasingly prevalent, particularly among pest species.

The continued selection pressure for virgin births in insect pests could lead them to exclusively reproduce in this manner, posing a significant challenge for agriculture. Since females produce only female offspring through virgin birth, their ability to spread would double, potentially exacerbating pest problems.

While some egg-laying animals like birds, lizards, and snakes can naturally switch to giving birth without males, virgin birth in sexually reproducing animals is rare. It is mostly observed in zoo animals and typically occurs when the female has been isolated for extended periods with little hope of finding a mate. This discovery adds valuable insights into the complex world of reproduction and could have implications for understanding and managing pest populations in agriculture.

Source: University of Cambridge

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