Entomology Today

Some Facts About Florida’s Genetically Modified Mosquitoes

A female mosquito (Aedes aegypti) fills up on human blood. In the process, she can also spread viruses, including Zika, dengue and chikungunya. A new review of existing research shows spatial repellents using volatile pyrethroids can be a useful tool in protecting humans from mosquitoes that may carry disease. (Photo credit: James Gathany, CDC Public Health Image Library)

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