Why Google wants to release 32 million mosquitoes in the US

Google is best known for search, Android and artificial intelligence. But one of its lesser-known projects involves mosquitoes.

Through Alphabet-backed biotechnology company Verily, Google is seeking regulatory approval in the United States to release as many as 32 million mosquitoes across California and Florida over the next two years. The proposal is part of the company's long-running "Debug Project", an effort aimed at reducing mosquito populations and limiting the spread of mosquito-borne diseases.

Why does Google want to release millions of mosquitoes?

The objective is not to increase mosquito numbers permanently but to reduce them over time. The project relies on releasing specially bred male mosquitoes that are unable to produce viable offspring. When these males mate with wild female mosquitoes, the eggs fail to hatch, gradually shrinking the overall population across multiple breeding cycles.

Researchers hope that reducing mosquito numbers will lower the risk of diseases transmitted by the insects.

What makes these mosquitoes different?

The mosquitoes being released carry a naturally occurring bacterium called Wolbachia. When Wolbachia-infected males mate with females that do not carry the same bacterial strain, the eggs do not develop. 

How does the technology work?

The biggest challenge is scale.

Mosquitoes are delicate and hard to breed in huge numbers. To solve this, Verily has built automated systems that can produce millions of mosquitoes and use machines to separate males from females before they are released.

The company says these systems allow it to deploy sterile male mosquitoes in quantities large enough to affect wild populations.

Has this approach been used before?

Yes. The underlying method, known as the Sterile Insect Technique, dates back to the 1950s and has been used successfully against agricultural pests such as fruit flies, screwworms and codling moths.

What results has Google seen so far?

Verily previously tested the approach in Fresno County, California.

Between 2017 and 2019, the company released around 48 million sterile male mosquitoes as part of a pilot programme. According to project data, local populations of biting female mosquitoes fell sharply during the trial, with some areas recording reductions of as much as 95%.

What happens next?

The proposal is currently under review by the US Environmental Protection Agency (EPA). The regulator is accepting public comments before deciding whether to grant an experimental permit for the mosquito releases. 

If approved, the programme could become one of the largest mosquito population-control efforts undertaken in the United States.