Brazil is fighting a war on mosquitoes. The current headline might be Zika, but the country’s bloodsuckers are also spreading dengue fever and other killer diseases. The answer could be technology, in the form of genetic modification. And while Brazil’s trials are aimed at stopping the spread of diseases like Zika and dengue, mosquito-haters will be happy to hear that GM often spells mosquito apocalypse.
To fight dengue, modified male Aedes aegypti mosquitos were deployed in Piracicaba, a city in the state of São Paulo. These "Friendly Aedes" skeeters, developed by U.K. company Oxitec, live for just four days, and their offspring don’t develop after becoming larvae. The trick is to seed the city with so many of these modified mosquitos that they beat out the local males and mate with the females. In 10 months of testing, annual cases of dengue fell from 133 (among 5,600 people) to one. The GM mosquitos are also marked so their larvae glow under the correct lighting, and this lets the Oxitec people count them. The numbers show an 80% drop in the wild mosquito population.
These mosquitos are bred in a local factory in the city of Campinas, at a rate of 2 million per week, and are seen by some as an answer to all mosquito-borne diseases in the country. Although the method is effective, it is also expensive. "To protect about 5,600 people who live in the test area," says MIT Technology Review, "[Oxitec] has been releasing between 3 and 4 million mosquitoes a month. Protecting all of Piracicaba, where Oxitec plans to build a new production site, would theoretically take 3 billion insects a year."
That expense is mitigated by two things. One is that going all-in on GM mossies means money can be saved by ditching older methods. "The reality is that with the success of the Friendly Aedes, the traditional methods can be abandoned," says mayoral spokesperson Carlos Eduardo Luccas Castro.
"The bill for the city of 390,000 would come to about $2.7 million a year," says MIT Technology Review, which is "approximately what the health department currently spends on sprays, larvicides, and costs like sick leave."
But savings aren’t the only way to pay for the mosquito factory. The city Piracicaba thinks it might be able to export the Friendly Aedes mosquitos to other Brazilian cities. That would depend on laws allowing them to do so, but it would be quite an ironic twist in an ongoing experiment to eradicate mosquitos.