Swarms of genetically modified mosquitoes could soon be descending on Florida

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Mosquitoes are best known for being a scourge responsible for everything from itch-inducing bites to the spread of dangerous diseases. That's not to say that they are without purpose, as many mosquitoes help pollinate plants and serve a vital role as a food source to fish, birds, and other predators above them on the food chain. But for the most part, mosquitoes are a pain in the ass, so much so that the Environmental Protection Agency has approved a new and controversial field test aimed at curbing their population. The plan is to release genetically modified mosquitoes that over time will lead to fewer regular mosquitoes.

Here's how the plan will work: Scientists at Oxitec, a UK-based company that specializes in genetically engineered insects, have created male mosquitoes with a modified gene. That gene gets passed down when they mate with female mosquitoes. The gene essentially guarantees that the female offspring that result from the mating process all die. This is important to controlling the population and stopping the spread of disease, as female mosquitoes are the ones who bite. Males, on the other hand, present no real threat to humans, meaning even though there may be more mosquitoes when these modified insects are first released, they should have no real effect on people other than the mild annoyance of their buzzing. Early tests of the plan are set to go forward later this year in Monroe County, Florida, where the Florida Keys are located. Additional tests have been approved for Harris County, Texas, which includes the city of Houston.

The test runs will target mosquito species that are known for their role in spreading dangerous diseases including Zika virus and dengue fever to humans. A study published in 2012 warned that as many as four billion people globally are at risk of contracting dengue fever, which can cause flu-like illness and even result in death for some, according to the World Health Organization. In the US alone, as many as 40 million people per year contract dengue fever, and an estimated 22,000 die from it, according to the Centers for Disease Control and Prevention. Zika virus often causes no symptoms in people who contract it, but it can cause serious complications during pregnancy and lead to birth defects. It can also cause Guillain-Barré syndrome, a rare sickness that causes a person's immune system to damage nerve cells, leading to weakened muscles and even paralysis. As many as 40,000 people in the US and its territories are infected with Zika each year.

It's projected that these diseases will only become more prevalent over time, caused largely by climate change. As the planet warms, the conditions only become more hospitable for mosquitos to reproduce. With more of the insects carrying the infectious diseases, researchers have projected that as much as half of the world's population will be at risk of contracting mosquito-borne diseases like dengue fever and Zika virus by 2050.

While the threat of a growing mosquito population certainly requires addressing, there is some concern about the unintended consequences of releasing genetically altered insects into the wild. Oxitec ran similar experiments to those planned in the US in Brazil and claimed to achieve a 95 percent reduction in the mosquito population. While other studies found the results to be less successful than Oxitec claims, it did result in at least a moderate decline in the overall population of disease-spreading insects. However, some have raised concerns that the modified mosquitoes that result from the mating may prove harder to control. Studies looking at the side effects of the release of genetically modified mosquitoes in Brazil found that the experiment resulted in a hybrid species that could reproduce. It's also unclear if the modified mosquitoes might have an effect on human or animal health, though the EPA and Oxtiec swear that there should be no impact on other species.

The EPA has maintained the right to end the field tests if any unforeseen outcomes occur, and there is certainly concern among citizens in communities where the experiments will take place. In Key Haven, Florida, residents voted overwhelmingly against the release of genetically engineered mosquitoes, concerned by potential side effects and unaccounted for risks. The tests will likely go forward sometime later this year and are sure to garner a lot of attention, as the gene-edited mosquitoes could either prove effective in stopping the spread of dangerous diseases or make the situation even worse.