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Some Facts About Florida’s Genetically Modified Mosquitoes

Over the weekend, a deluge of news articles about the possible release of genetically-modified mosquitoes in the Florida Keys swept the Internet. The modified mosquitoes, if approved, would be used to control mosquito populations without pesticides, and would lower the chances of Floridians being exposed to mosquito-borne diseases like dengue and chikungunya.

Some of the articles were somewhat alarmist. The Washington Post, for example, managed to use the words “Genetically modified killer mosquitoes” in its headline and later referred to them as “Frankenstein mosquitoes.”

The Associated Press, in an article that’s been circulated by many other media outlets, wrote “Never before have insects with modified DNA come so close to being set loose in a residential U.S. neighborhood.” While it’s true that this particular type of genetic modification, which results in unviable offspring after modified males mate with unmodified females, has never been used in the U.S. before, a similar concept called the Sterile Insect Technique (SIT) has been used in Florida for years. In fact, the state spends roughly $6 million a year using SIT to prevent Mediterranean fruit fly infestations, while California spends about $17 million a year. The Sterile Insect Technique was developed back in the 1950s and was used successfully in the U.S. against the screwworm (Cochliomyia hominivorax), which was finally eradicated in 1982.

My favorite quote (so far) appeared in an editorial from the Daily Free Press, which said, “These mosquitoes would be used to bite people and essentially make them immune to dengue fever and chikungunya, two extremely painful viral diseases that currently have no vaccines or cures.”

Although that sounds kind of cool — I’d be happy to be bit by such a mosquito, if it existed — nothing could be further from the truth. Oxitech, the British company that developed this new genetic-modification technique — known as RIDL (Release of Insects carrying a Dominant Lethal) — only tinkers with the DNA of the male mosquitoes, which do not bite. The males are basically good for one thing only — mating — and after they do the deed, the offspring they produce will never make it to adulthood.

Further in the article, the Daily Free Press editors reason that mutant mosquitoes that somehow vaccinate people with their bites could be a good thing in other parts of the world — which is nice of them if you think about it — they just don’t want them in their own backyard.

“If Oxitec decided to make an Ebola vaccine, inject it into mosquitoes and release them somewhere where cases of Ebola are rampant and uncontrolled, that would be a much better use of genetically modified insects,” they wrote.

So what does the entomological community think? While it’s nearly impossible for everyone to agree on something like this, we do know that the Entomological Society of America presented its 2014 Nan-Yao Su Award for Innovation and Creativity in Entomology to Dr. Luke Alphey, an Oxitec scientist. This award is given annually to an entomologist “who is able to demonstrate through his/her projects or accomplishments an ability to identify problems and develop creative, alternative solutions that significantly impact entomology,” and Dr. Alphey received it for “developing innovative technology known as RIDL (Release of Insects carrying a Dominant Lethal) to control insect pests, based on the use of engineered sterile males of the pest insect species.”

In the following CNN video, Dr. Alphey explains the genetic-modification process:

In addition to mosquitoes, Oxitec’s RIDL technique has been applied to olive flies in Europe, where it is awaiting approval for field testing, and to the Mediterranean fruit fly.

Oxitec’s mosquitoes were previously released in Panama and Brazil, where they achieved a 96% suppression of the dengue mosquito.

“Oxitec’s approach has already shown great promise,” said Dr. Nestor Sosa, director of the Gorgas Institute in Panama. “It’s a technology that is completely specific to the dengue mosquito we are targeting, and by helping to reduce our reliance on chemical pesticides, it could also be beneficial for the environment.”

Richard Levine is Communications Program Manager at the Entomological Society of America and editor of the Entomology Today Blog.

Richard Levine


  1. So, it’s so much better that you have big trucks (or airplanes) riding around, dousing everything with pesticides that have who-knows-what side effects (one of multiple reasons I’m getting the heck out of Florida). It’s bad enough that practically everyone in Florida, city officials, private homeowners, business owners douse every square inch of lawns, landscaping, and sidewalks with Round-up, then we have to deal with the mosquito spray as well. Once I parked on the street in my friend’s neighbourhood and my entire car was doused in pesticides from a mosquito-spraying truck. I made my friend give me money for an immediate car wash. <—born and raised in Florida and love the "old Florida" environment (relatively speaking) without toxic green lawns, weed-free sidewalks (Round-up, again) and year-round red tide.

  2. I’m puzzled by the choice of lead illustration here – does the genetic modification cause mosquitoes to have a second pair of wings, not halteres, and 8 legs?

  3. Nancy, the illustration was meant to be ironic — sort of poking fun at news articles with headlines like “Genetically modified killer mosquitoes may attack Florida Keys” (a real headline from the Washington Post — seriously). Rest assured that the GM mosquitoes will still only have two wings and six legs. Also, they will not have silly little cartoon eyeballs, nor will they grow hair on their heads, nor will they develop upturned proboscises, or mouths capable of smiling. Everything’s gonna be OK :)

  4. It is sad that so many people automatically “freak out” these days when the words “geneticaly modified” are used. The truth is humans have been genetically modifying animals and plants for ages – the technique is called “Selective breeding” and you may have a”genetically modified organism” right in your own backyard – the lovable and well-distributed pet dog. Not to mention any number of species of pet fish, birds, rodents, houseplants, roses….All science has done is made it a more controlled and faster process, without having to wait twenty generations to see the results.

  5. With all my respects here is an article about the olive fly where Oxitec have to withdraw the applicants on because they could not answer all the questions to European regulators.

    • Thanks, Mila. We checked this out with a scientist who is familiar with it, and it appears that, in his words, “this a completely misleading story built by taking some simple facts and twisting them beyond recognition,” so we’ve removed the link to the article in your comment so as not to publicize misinformation.

      Regarding the olive fly case, Oxitec applied for a permit for a field cage trial in Spain. The regulators were generally positive but had a number of questions. Some could be answered immediately but a few needed more data. This is typical. The initial application was therefore withdrawn while Oxitec got that data.

      Regarding Brazil, the medfly application was in fact approved. Comments about ‘withdrawn from the agenda’ perhaps relate to committee procedures. Regarding Oxitec’s OX513A mosquito strain, that received full technical approval for commercial release from CTNbio.

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