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In an attempt to reduce the number of disease-carrying mosquitoes in Florida, scientists turn to genetic modification.

Mosquitoes can be annoying, but how far would we go to stop them?

In an attempt to reduce the number of disease-carrying mosquitoes in Florida, scientists turn to genetic modification.

Genetically Modifying Mosquitoes to Reduce their Numbers

Mosquitoes can be annoying, but how far would we go to stop them?

Tech & Engineering

Genetically Modifying Mosquitoes to Reduce their NumbersPublished: September 27, 2021Narrator: Mosquitoes can be annoying, but how far would we go to stop them? Some researchers are genetically modifying one especially pesky species of mosquito in an attempt to reduce its numbers. The Aedes aegypti mosquito spreads some serious diseases. Omar Akbari: Pathogens that can affect humans like dengue virus, Zika virus, yellow fever, chikungunya. You can just simply spray insecticides and hopefully kill the mosquitoes that way. The problem with insecticides are, they not only target mosquitoes, but they also target beneficial insects like honey bees and butterflies and things like that. And then, there's numerous examples of Aedes aegypti mosquitoes evolving resistance rapidly to insecticides. So insecticides are no longer as effective as they used to be. So we need new solutions. Why not use the mosquitoes to control themselves? Narrator: For the first time, genetically modified male mosquitoes have been released in the U.S. — created by a biotech firm called Oxitec. Nathan Rose: It's only the female Aedes aegypti, which actually bite people and which can transmit diseases. So the males that we release that carry these genes cannot bite anyone and they cannot transmit any disease.Narrator: These male mosquitoes carry something called a self-limiting gene. Rose: It's passed on to all of their offspring and all of their female offspring that inherit that gene will die at really early larval stages of development. Narrator: In other words, when a genetically modified male mates with a female mosquito, then all their eggs should inherit the self-limiting gene. And as a result, the female mosquito larvae won't survive. Akbari: Only the females will die and the males will survive. So the next generation, the males are then going to go mate with wild females again and continue the cycles.Narrator: The goal is that as generations go on, more and more females die, leaving mostly male mosquitoes — which again, don't bite people — and since males don't produce eggs...Rose: We start to see that the overall size of that mosquito population actually diminishes pretty rapidly.Akbari: And the goal is that if you release enough of these males, then eventually, potentially, you might hit a point where there's no more females left and you can get eradication of the population. They haven't demonstrated that yet, but they do show that you get population suppression.Narrator: This method's already been employed in other places around the world. For instance, a four-year program in Piracicaba, Brazil targeted an area with about 60,000 residents. Rose: It's been used safely in Brazil for many years. We have seen that we can reduce the population of these invasive species. And in the United States, it's been through a very stringent regulatory process. Narrator: Oxitec not only had to get approval from the U.S. Food and Drug Administration and the U.S. Environmental Protection Agency, but they also worked with Florida state regulators and agencies. But what about concerns that these genetically modified mosquitoes will impact the local ecosystem? Rose: The aedes aegypti mosquito is invasive in the Americas. And in the Florida Keys, it makes up less than four percent of all of the mosquitoes that are actually present in that ecosystem. There's no animal that actually depends on it for food, and it's not carrying out any other vital ecosystem functions. It's really just there biting people and sometimes spreading disease. Akbari: They're everywhere. I mean, I find them in my backyard. It's a consequence of global warming. The environment is getting warmer, so their habitable range is expanding. As this mosquito establishes itself and spreads throughout more northern states in the United States and becomes more prevalent, it's possible that we might start seeing more dengue transmission.Narrator: Getting rid of mosquitoes — even if it is just one species — may seem like a good idea. But as bioethicist Alta Charo notes, there may be some risks whenever genetically modified species are released into the wild. Alta Charo: Where is this experiment being done? Who are the people who might be harmed in some way? And are they the same people who are going to be getting the benefits or do the benefits flow to somebody else? The more that there's a disconnect between benefit and risk, the more you have a problem.We have been modifying things for all of human history. Every time farmers tried to cross one plant with another, what they were doing was trying to modify genetics. They were doing it inefficiently. They were doing it with a lot of guesswork, and they were doing it in a way that might or might not have an outcome you like. So it's not as if manipulating genetics is something new. It's simply that we now have more powerful tools. They make it more precise, but they also give us more things we can do. And it's really about our ability to take advantage of that power without losing control of the power.You build in a requirement for some kind of control and mitigation measure. We can slow it, stop it, reverse it, mitigate the effects — which makes it possible to take more chances and get the benefits but reduce the risks.Narrator: Oxitec says they have strong support within the Florida Keys — with 31 out of 33 precincts in the county voting for the project in 2016. The results of this project may ultimately help address concerns about releasing genetically modified organisms into the wild.Akbari: I think one misconception is that people think, you know, if you're removing a mosquito, you're removing all mosquitoes. In my opinion, I think it's more ethical to remove it, if you can, than to let it continue to transmit these pathogens that are very deadly.

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Genetically Modifying Mosquitoes to Reduce their Numbers

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Support Provided By

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For Gene Drives, Resistance May Be Inevitable

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