Wiping out the mosquito species carrying the Zika virus is a good case for gene modification – South China Morning Post (subscription)


It was a typically anodyne statement by the World Health Organisation: “Given the magnitude of the Zika crisis, WHO encourages affected countries and their partners to boost the use of both old and new approaches to mosquito control.” Anodyne, that is, until you realise what they mean by “new approaches”.

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Zika is a mosquito-borne virus that is spreading panic around the world. It was first linked to microcephaly – a developmental defect in infants – only last year in Brazil. The WHO estimates it may infect 3 to 4 million people in the Americas alone this year – and its “new approach” is to exterminate the mosquitoes. Literally.

An alternative would be to develop a vaccine for the virus – but that would take up to 10 years, and the crisis is now. Zika has already been detected in 30 countries. The pressure is on to do something fast.

By coincidence, something fast is available. Austin Burt, an evolutionary geneticist, raised the idea of a “gene drive” that would spread some desirable quality (like immunity to malaria) through an entire population in a relatively short time. By last year, scientists had a genetically modified (GM) mosquito whose offspring do not survive into adulthood.

READ MORE: World Health Organization declares Zika a global emergency

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By an even wilder coincidence, the species of mosquito was Aedes aegypti, best known as a vector for dengue fever and also the main transmitter of the Zika virus. Oxitec, the company created to exploit this new technology, is already field-testing the GM version of the insect – in Brazil.

Human beings have wiped out entire species in the past, but we never actually intended to do so

In the town of Piracicaba, Oxitec has a “factory” that produces 800,000 mosquitoes each week that carry the OX513A gene, and a white van that sets them free all over town. In theory, they should mate with the local females, whose children will never grow up to mate themselves, so the local population should go into steep decline. And, in practice, it works. Obviously, the enterprise could be scaled up. The question is: should it be? Human beings have wiped out entire species in the past, but we never actually intended to do so.

Some environmentalists claim removing an entire species of mosquito would upset the ecological balance. But one suspects their real worry is the “slippery slope”. If we edit Aedes aegypti out of existence, what species will be next? The threat of Zika will trump their arguments.

The great American biologist and champion of biodiversity E. O. Wilson gets the last word on this. In his book The Creation: An Appeal to Save Life on Earth, he makes an exception for Anopheles gambiae, the mosquito that spreads malaria in Africa. “Keep their DNA for research,” he writes, “and let them go.” The same goes for Aedes aegypti. We are going to commit insecticide. And we should.

Gwynne Dyer is an independent journalist

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