Scientists are genetically modifying mosquitoes in a high-security lab – and they're hoping the insects will help wipe out some of the mosquito-borne diseases that continue to plague communities worldwide.
It's known as a gene drive: where mosquitoes modified to be incapable of passing on a particular virus are used to replace the existing population of insects over several generations, with the modified genes being passed on to all their offspring.
The idea has attracted controversy because it messes with the fundamentals of nature, but it's now under consideration by the World Health Organisation (WHO). This particular testing has entered a new phase, NPR reports, with a large-scale release of genetically modified mozzies inside a facility in Terni, Italy.
"This will really be a breakthrough experiment," entomologist Ruth Mueller, who runs the lab, told Rob Stein at NPR. "It's a historic moment. It's very exciting."
Using the 'molecular scissor' editing technique CRISPR, a gene known as "doublesex" in the bugs has been altered. The gene transforms female mosquitoes, taking away their biting ability and making them infertile.
At the moment, the bugs are being released in cages designed to replicate their natural environments, with hot and humid air, and places to shelter. Artificial lights are used to simulate sunrise and sunset.
The idea is to see if the mosquitoes with CRISPR-edited genetic code can wipe out the unmodified insects inside the cages. It follows on from previous proof-of-concept studies that we've seen before.
Ultimately these mosquitoes could be released in areas hit by malaria, bringing the local mozzie population crashing down and saving human lives. The disease is responsible for more than 400,000 deaths every year – mostly young children.
Reducing those figures sounds like a great idea, so why the controversy? Well, many scientists are urging caution when it comes to altering genetic code at this fundamental level – we just don't know what impact these genetically edited mosquitoes will have on the world around them.
For that reason the lab has been designed to minimise any chance that the specially engineered mosquitoes could escape. The testing has also been specifically located in Italy, where this mosquito species – Anopheles gambiae – wouldn't be able to survive outside in the natural climate.
"This is a technology where we don't know where it's going to end," Nnimmo Bassey, director of the Health of Mother Earth Foundation in Nigeria, told NPR. "We need to stop this right where it is. They're trying to use Africa as a big laboratory to test risky technologies."
Some experts think adding genetically modified mosquitoes to natural ecosystems could harm other plants and animals that depend on them. There are a lot of unknowns.
The team behind the new experiments counters the critique by saying they're working slowly and methodically – and that the potential side effects are outweighed by the benefits of eradicating malaria.
At the moment scientists are targeting just one species of mosquito out of hundreds, and several more years of research and consultation are planned before genetically edited mozzies would ever be released.
"There's going to be concerns with any technology," one of the research team, Tony Nolan from Imperial College London in the UK, told NPR.
"But I don't think you should throw out a technology without having done your best to understand what its potential is to be transformative for medicine. And, were it to work, this would be transformative."