May 9, 2022 — Genetically modified mosquitoes released in the U.S. appear to have passed an early test that suggests they might one day help reduce the population of insects that transmit infectious diseases.
As part of the test, scientists released nearly 5 million genetically engineered male Aedes aegypti mosquitoes over the course of 7 months in the Florida Keys.
Male mosquitoes don’t bite people, and these were also modified so they would transmit a gene to female offspring that causes them to die before they can reproduce. In theory, this means the population of Aedes aegypti mosquitoes would die off over time, so they wouldn’t spread diseases any more.
The goal of this pilot project in Florida was to see if these genetically modified male mosquitoes could successfully mate with females in the wild, and to confirm whether their female offspring would indeed die before they could reproduce. On both counts, the experiment was a success, Oxitec, the biotechnology company developing these engineered Aedes aegypti mosquitoes, said in a webinar.
More Testing in Florida and California
Based on the results from this preliminary research, the U.S. Environmental Protection Agency (EPA) has approved additional pilot projects in Florida and California, the company said in a statement.
“Given the growing health threat this mosquito poses across the U.S., we’re working to make this technology available and accessible,” Grey Frandsen, Oxitec’s chief executive, said in the statement. “These pilot programs, wherein we can demonstrate the technology’s effectiveness in different climate settings, will play an important role in doing so.”
Preliminary tests of the genetically modified mosquitos weren’t designed to determine whether these engineered insects might stop the spread of these diseases. The goal of the initial tests was simply to see how reproduction played out once the genetically modified males were released.
The genetically engineered males successfully mated with females in the wild, the company reports. Scientists collected more than 22,000 eggs laid by these females from traps set out around the community in spots like flowerpots and trash cans.
In the lab, researchers confirmed that the female offspring from these pairings inherited a lethal gene designed to cause their death before adulthood. The lethal gene was transmitted to female offspring across multiple generations, scientists also found.
Many more trials would be needed before these genetically modified mosquitos could be released in the wild on a larger scale – particularly because the tests done so far haven’t demonstrated that these engineered bugs can prevent the spread of infectious disease.
Releasing genetically modified Aedes aegypti mosquitoes into the wild won’t reduce the need for pesticides because most mosquitos in the U.S. aren’t from this species.