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Genetically-modified fruit flies could control wild populations by producing only sons


August 13, 2014

Male medflies that are genetically altered using the RIDL technique don't produce viable female offspring (Photo: Oxitec)

Male medflies that are genetically altered using the RIDL technique don't produce viable female offspring (Photo: Oxitec)

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Mediterranean fruit flies are responsible for extensive damage to fruit and vegetable crops, not only in the Mediterranean region but also in Australia, North and South America. While existing methods of controlling them include the use of insecticides and sterilization, the University of East Anglia and biotech company Oxitec are pioneering what they claim is a greener and less expensive approach –  they're genetically modifying male fruit flies to produce only male viable offspring.

In the existing sterilization approach, radiation is used to render captive male "medflies" sterile – it's known as the Sterile Insect Technique (SIT). When those flies are released into wild populations, they mate with females that would otherwise be mating with wild males. Because the SIT males are sterile, however, those couplings don't result in any fertile eggs, thus lowering the population.

One of the problems with SIT, however, is that the irradiation process weakens the flies, lessening their ability to mate properly. That's where the UEA/Oxitec process, called RIDL (Release of Insects Containing a Dominant Lethal), comes in.

It doesn't involve radiation, but instead introduces a gene that keeps male flies' female offspring from reaching the reproductive stage. The treated males are said to be healthier than those subjected to SIT, and will readily mate with wild females once they're released. Those females will in turn lay fertile eggs, but all of the resulting female babies will die before they're able to produce offspring of their own.

In lab tests conducted in medfly-containing greenhouses at the University of Crete, RIDL reportedly resulted in a "rapid population collapse." UEA and Oxitec are now seeking approval for open-field trials of the technology.

Previously, Oxitec has collaborated with the University of California, Irvine, on a system in which genetically-modified male mosquitoes produce female offspring that lack wings. These flightless females can't reach humans, and are easy pickings for predators.

A paper on the RIDL research was published this Wednesday in the journal Proceedings of the Royal Society B.

Sources: University of East Anglia, Oxitec

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

At first I wondered what species would suffer from the lack of fruit flies as a food source, but that species would probably benefit from the lack of a need to use insecticides. This solution seems like a great net positive and not just for the profits of the companies involved.

The wingless female mosquito idea is also brilliant. They still survive to be food for mosquito predators. An enemy of my enemy...


Releasing Frankenflies into the environment is not a good idea.


This could mutate. Sex universally is much more diverse than human.

Art Toegemann

Looks good on paper, too ad we don't have another planet to practice on

Jay Finke

interesting but very very risky.


would this work with mosquitoes as well?

Pranav Vissanji
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