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In the Wake of the Zika Virus, Should Humans Try to Eradicate Mosquitoes?

A worker sprays DDT directly into a water supply during the National Malaria Eradication Program. (Photo: CDC Public Health Image Library, ID#4684)

Mosquitoes might just be the most unpopular insect on Earth. At their most harmless, they cause infuriatingly itchy welts, ruining barbecues and birthday parties around the globe. At their worst, they’re vectors for serious diseases like malaria, Dengue fever, West Nile virus, and the Zika virus, which experts now think may be a bigger threat to global health than the recent Ebola epidemic.

The threat is so severe that some, such as Wellcome Trust head of infection and immunobiology Mike Turner, are advocating the use of DDT—long banned in the United States and elsewhere due to its environmental and health risks—to eliminate the mosquito species’ that serve as carriers of the virus.

This weekend, a few pundits have taken things one step further by calling for the eradication of all mosquitoes.

Purposefully eradicating an entire species sounds outrageous, but we already use a variety of strategies to control mosquito population growth. Famously, in 1947, the U.S. carried out the National Malaria Eradication Program, blanketing the southeast in DDT and eradicating malaria in the U.S. in just four years. Today, New Yorkers and other urbanites are likely familiar with local pesticide-spraying events to combat the spread of West Nile virus and other mosquito-borne illnesses. And looking forward, many scientists are moving beyond pesticide and looking to genetically modify mosquitoes to control—or even eliminate—certain populations. The modifications come in a variety of flavors; one team modified mosquitoes’ smell receptors, eliminating their ability to smell nearby humans. Professor Anthony James and colleagues at UC Irvine modified Aedes aegypti so that female mosquitoes were born without wings, crippling their ability to survive and reproduce. Right now, mosquitoes possessing a lethal gene that prevents them from reaching adulthood are being released in Brazil to reduce mosquito numbers and, hopefully, control the spread of the Zika virus.

Humans have shown an aptitude for unwittingly driving other species to extinction, but should we really turn our talents towards purposeful eradication? Some scientists have argued that the consequences of allowing mosquitoes to live outweigh any dangers posed by removing them from the ecosystem. Carlos Brisola Marcondes, a medical entomologist, tells Nature unequivocally that a world without mosquitoes would be “more secure for us,” and biologist Olivia Judson argued in the New York Times that other insects could easily replace mosquitoes’ role in any ecological niche. But each of these arguments have a counter—entomologist Phil Lounibus points out that whatever replaces the mosquito could be “equally, or more, undesirable from a public health viewpoint”.

Even if the idea seems sound from a biological perspective, many are ethically squeamish about purposefully eliminating another species. That might be why some scientists have focused on less murderous ways to lessen the health impacts of mosquitoes. The Kew Royal Botanical Gardens is working on a project to track harmful mosquitoes with acoustic devices, and James has moved on from removing wings to genetically modifying mosquitoes so they can’t spread disease.

Regardless of whether you think mosquitoes should be driven from the Earth, or simply made a little less dangerous, large-scale implementation of these strategies is probably a long way off; but the next time you find yourself scratching, take comfort in the fact that future could hold a mosquito-free world.