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These Mosquitos Have A Genetic On-Off Switch That Makes Them Sterile

An insect birth control program with benefits for humans.

These Mosquitos Have A Genetic On-Off Switch That Makes Them Sterile

[Photo: Kevin Frayer/Getty Images]

A new method for breeding sterile mosquitos might make disease control a lot more efficient and allow mass deployment against the tiger mosquitos that carry Zika, yellow fever, and dengue fever.

A research team from Giessen, Germany, has come up with a genetically modified male mosquito that breeds with females. Because of the modifications, the resulting eggs will not develop past larval stage. The idea is that you flood an area with the sterile insects that eventually decimate wild populations.

So far, this is exactly the same as the company Oxitec's Brazil experiment, which has achieved great success over its first year. The problem, though, is how do you breed a sterile insect?

[Photo: Flickr user Jim Stauffer]

The team, from the Fraunhofer Institute for Molecular Biology and Applied Ecology, is making an insect whose sterility can be switched on, in this case by feeding them an antibiotic. The mosquitoes can be bred in captivity, with normal, viable offspring, and then, when it’s time to launch, they are fed a little of the trigger antibiotic (tetracycline) to switch on their sterility gene.

The team, led by professor Marc Schetelig, has already designed a vinegar fly to do the same. This fly, the spotted-wing drosophila, is destroying fruit harvests in Europe because it waits until just before harvest to attack the fruit, when pesticides can no longer be used. Schetelig is taking his successful fruit fly techniques and applying them to the tiger mosquito.

You may have noticed one other gap in the plan. What about all those female mosquitoes that are bred along with the males? Schetelig’s team has that covered. They added another genetic switch that causes the females to die at the embryonic stage. "With this sexing system, we can considerably improve the effectiveness of mass breeding, because we raise only the males. Females need to be sorted out," he says in a press release.

Schetelig is also aware that genetic modification might not be the answer everywhere. Some countries, for instance, are wary of allowing any GM insects to be released into the environment, so he is investigating what the ramifications could be.

And there are alternatives to GM-sterilized mosquitos. They can also be sterilized with radiation, administered after breeding and before release. Schetelig points out that the level of acceptance of any technique is in proportion to the risk factor. "If we had the same problems with dengue fever and Zika virus in Germany as they have in Brazil, we would also be searching for and evaluating different solutions," he says.

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