Genetically modified mosquitoes, designed to fight spread of dengue fever

Dengue is a scourge of a disease. It’s spread by mosquitos and kills more than a million people every year.

The disease is carried by mosquitoes, mostly the Aedes aegypti. Found in urban areas, Ae. aegypti has proven a particularly difficult mosquito species to control—it has developed a resistance to common insecticides and, because it bites during the day, bed nets are no protection against it. But now Brazilian health officials are running a pilot program using genetically modified mosquitoes to breed the population to death. The mosquitoes are the invention of British biotech company Oxitec, and they’ve had a gene inserted into them that kills them. In the lab, the mosquitoes can be fed a sort of antidote: a supplement that keeps them alive until it’s time to release them. Once they’re released, the clock starts ticking.

Oxitec’s mosquito-suppression solution consists of releasing the modified male mosquitoes into the wild—male mosquitoes don’t bite; it’s the females who do. The Oxitec males mate with female mosquitoes and create progeny that also have the lethal gene. Without the supplement, those progeny die. “By applying the Oxitec Control Programme to an area,” the company’s website says, “the mosquito population in that area can be dramatically reduced or eliminated.”

Remarkable. Here’s hoping this works, with no hidden consequences.

  • Patrick Henry,The2nd

    Not a bad solution, but it ignores another excellent one: DDT. It has excellent killing ability and is environmentally safe when used properly (it’s a myth and actual fiction that it kills birds). By banning DDT so many years ago the world has condemned millions to death based on no evidence. But that’s typical, sadly.

    • Stephen Wood

      Er. Developing countries still use DDT to control malaria. While DDT isn’t the main cause of bird egg shell thinning, one of its biological metabolites, DDE, is responsible for this.

      • James Hughes

        Some strains of Aedes aegypti are resistant to DDT as well.

    • I wouldn’t want more DDT despite your claim. One of its downsides is that the human body can’t properly get rid of it, but there a better source of information than me:


    “no hidden consequences”

    I guess when you don’t understand Evolution then you going to make such pronouncements.

    Magical Thinking.

    • JohnDoey

      First of all, it’s “evolution,” not “Evolution.”

      Secondly, being unconcerned about the consequences of introducing a self-killer gene into the wild that is passed from parent to progeny and meant to kill off a whole species is magical thinking. That is a very, very serious thing to do, both from the perspective of genetics and from the perspective of habitat management. Is that gene never going to move to another host via a virus? And what is going to replace the mosquito in that biome? Something better, or something worse? What other species are we going to lose as a result? For example, a bird that eats the mosquito may die out, and then another animal that eats those birds may die, too. And then a tree species that reproduced via those birds eating its seeds and excreting them elsewhere may die, too. These are all very rational, non-magical questions.

      • Moeskido

        And the potential consequences you’re describing are often enough what happens when someone in a corporate lab comes up with a magic bullet that attempts to solve one problem without considering anything outside of that problem.

  • This is such a bad idea. Haven’t we learned anything from the amount of times we’ve all watched Jurassic Park?

    In all seriousness, haven’t we learned our lesson from Monsanto’s cockamamie idea of genetically modified seeds? Stuff like this can’t be contained.

  • If it really just kills the mosquito and doesn’t cause any other side effects. But thats as likely as me winning the lottery…

  • Moeskido

    It’s a biotech magic bullet. Of course there will be consequences.

  • what could go possibly wrong?! smirk…

  • JohnDoey

    What happens when this gene jumps into humans or other animals via a virus?

    • normm

      What they actually used is a defective gene in the male that prevents its offspring larvae from growing into adults. The way they did it doesn’t seem any more dangerous to other species than a random mutation that makes a mosquito sterile.

  • normm

    The story quoted has the science confused. The males are given a genetic defect that only kills larvae, not adults. The females see them as normal healthy males and want to mate with them. The resulting larvae die.

    How do they breed adults with the disease then? The genetic defect doesn’t kill the larvae if there is tetracycline present during their development.

    This is a very specific genetic disease that interferes with a mosquito-specific development process. It’s self limiting because it prevents reproduction. If some other species of mosquito were to somehow get the genetic disease due to virus transfer, it wouldn’t be able to pass it on since it’s fatal to the offspring.

  • Matthew Shettler

    They talked about this recently on Radiolab: One thing that deadly mosquitoes do is prevent people from venturing too much into the rain forests. It’s possible that eliminating mosquitoes as a threat could enable further deforestation.