Scientists in Italy have started their first large-scale laboratory release of genetically modified mosquitoes to fight malaria, NPR reports.

The team of scientists believes the insects could help combat the diseaase, which is spread through the bites of female mosquitoes. Using a gene-editing technique called CRISPR — which allows scientists to cut and paste pieces of DNA — researchers have been able to alter a gene called “doublesex” in the mosquitoes, which affects their sexual development.

That means the genetically modified mosquitoes, though technically female, also have male characteristics — including a mouth that can’t bite and, in turn, can’t spread the malaria parasite. The genetic mutation also deforms female mosquitoes' reproductive organs, preventing them from laying eggs and producing offspring. 

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Over time, this could also lead to a decrease in the mosquito population and the potential extinction of the species, the effects of which are not yet known. However, the scientists are optimistic.

"The known harm of malaria so outweighs the combined harms of everything that has been postulated could go wrong ecologically," said Kevin Esvelt, an evolutionary engineer at the Massachusetts Institute of Technology.

Some researchers believe that the modified insects could, in fact, even save endangered ecosystems and create more efficient crops. Researchers believe they could also help to eradicate other mosquito-borne diseases like dengue and Zika.

The scientists hope that spreading the mutation will eventually sterilize the female mosquitos that are specifically responsible for transmitting malaria, including from the Anopheles gambiae, Anopheles coluzzii, and Anopheles arabiensis species.

The idea to genetically modify mosquitoes to combat malaria was first proposed in a paper in 2014 by Target Malaria, a nonprofit research organization that develops research and technology to reduce the disease, according to Vox. And this month’s test is the organization’s latest effort, which is funded by the Bill & Melinda Gates Foundation.

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Critics fear these modified mosquitoes could disrupt the ecosystem by getting rid of pollinators that are necessary for growing crops. Others have questioned the morality of genetically modifying mosquitoes and other organisms and of using African countries, where malaria rates are high, as testing grounds.

"This is a technology where we don't know where it's going to end. We need to stop this right where it is," said Nnimmo Bassey, director of the Health of Mother Earth Foundation in Nigeria. "They're trying to use Africa as a big laboratory to test risky technologies."

Scientists are still working to find other alternatives for reducing malaria.

In 2015, a group of scientists at the University of California in San Diego and Irvine created a CRISPR gene drive for the Andopheles stephensi mosquito, which is mainly responsible for spreading malaria in India and South Asia, that made the insects resistant to the malaria parasite.

Last month, researchers also discovered a bacterium that is found inside nematodes — also known as roundworms — which repels mosquitos three times more effectively than DEET, a leading commercial repellent.

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“With malaria, I think, who are the people mostly affected and most affected by decisions made about gene drives?” said Keisha Ray, a professor of philosophy and bioethicist at Texas State University. “It’s not going to be the wealthy people in wealthy countries. It’s going to be people of color. It’s going to be poor people.”

Almost half of the world’s population lives in regions that are at risk for malaria transmission. The parasite is commonly found in tropical and subtropical areas, and it disproportionately affects communities of poverty, according to the CDC.

The Target Malaria project plans to continue to study the environmental impact of these modifications within the next few years.