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  • Mosquitoes suck. And not just literally, their bites are also itchy and annoying, and certain

  • species transmit parasites and viruses -- like the ones that cause Malaria, Yellow Fever,

  • and Zika -- infecting and killing hundreds of thousands of people each year.

  • And when we told you about the Zika virus a couple weeks ago, a lot of you had the same question:

  • Why don’t we just kill them all? All of them! Kill all the mosquitoes!

  • Humans are historically really good at making things go extinct. So it shouldn’t be too

  • hard to get rid of these bloodsuckersright?

  • Yeah... not exactly.

  • First of all, there are over 3,000 mosquito species worldwide, and only a couple hundred

  • of them bite humans.

  • Mosquitoes have been around for a lot longer than people, millions of years, and have survived

  • lots of predators and environmental changes.

  • So that would be a lot of tough insects to kill, and a lot of bug deaths that wouldn’t

  • affect humans at all.

  • And weve tried to eradicate mosquitoes before, mostly using chemicals that turned

  • out to be awful for both the planet and us, like DDT.

  • But let’s pretend that we were actually able to kill all the mosquitoes in some not-environmentally-apocalyptic

  • way. Say, if I wished on a star, and the next day all mosquitoes just poofed out of existence.

  • Would that be so bad for the Earth?

  • Some scientists actually say no -- that if mosquitoes were suddenly ripped out of food

  • webs, most ecosystems would heal pretty quickly, and other organisms would fill in those gaps.

  • But other scientists argue that certain mosquito species do play important ecological roles.

  • Take the mosquitoes that live in the Arctic of Canada and Russia.

  • They fly around in gigantic thick swarms and make up a huge part of the biomass there. And these

  • mosquitoes pollinate Arctic plants and are a major food source for migrating birds.

  • Removing these guys -- or other, more southern species that are food for fish, birds, and

  • other insects -- could send a ripple through ecosystems, endangering many other plants

  • and animals.

  • So we probably shouldn’t kill all the mosquitoes.

  • But, we also don’t have to. We know which species are vectors, or carriers, of the worst

  • viruses and parasites that can infect humans.

  • So lots of researchers are currently targeting these species, and developing ways to kill

  • them, or to kill the dangerous stuff inside them.

  • Take the genus Aedes, which transmits lots of awful diseases. One particularly nasty

  • species is Aedes aegypti, which is the primary vector for the Yellow Fever, Dengue, Chikungunya,

  • and Zika viruses.

  • A. aegypti is not just a pest, it’s one of the most medically significant pests. So

  • it’s the focus of lots of recent experiments in targeted mosquito eradication.

  • But some of the most promising research doesn’t set out to kill mosquitoes outright -- instead,

  • it genetically modifies them.

  • In 2015, a British company called Oxitec created male A. aegypti mosquitoes with a self-limiting

  • gene, which basically means that the gene can stop their cells from functioning normally.

  • When these genetically modified mosquitoes are released and mate with females in the

  • wild, the self-limiting gene gets passed on to their offspring.

  • Those offspring usually can’t develop properly and die before they become adults.

  • No adult mosquitoes means no disease transmission.

  • Likewise, a team of scientists in California inserted modified genes into a species of

  • Anopheles mosquitoes, which are vectors for the parasite that causes Malaria.

  • The modified genes cause the mosquitoes to kill the Malaria-causing parasites that live

  • inside them, before they can transmit them to humans.

  • And as a bonus, these parasite-destroying genes are designed to be passed on to 99.5%

  • of the mosquitoesoffspring.

  • So, eventually, this entire species could be unable to transmit Malaria. And scientists

  • think that this same technology could be applied to other mosquito species, and other parasites

  • and viruses -- like Zika.

  • Lastly, some scientists are fighting fire with fire -- or fighting viruses with bacteria

  • -- by intentionally infecting A. aegypti mosquitoes with a bacterium called Wolbachia.

  • Wolbachia seems to stop most viruses from growing inside these mosquitoes. So even if

  • the mosquitoes bite people infected with, say, the Dengue virus, the virus wouldn’t

  • survive inside the mosquito long enough to be transmitted to a new person.

  • Now, because viruses mutate rapidly, scientists worry about accidentally creating deadly viruses

  • that are resistant to Wolbachia.

  • But a study released this week suggested a strategy to superinfect mosquitoes with more

  • than one strain of the bacteria at a time.

  • This way, the viruses can’t develop resistance to the bacteria as easily. And we can keep

  • infecting mosquitoes, to keep them from infecting us.

  • I mean, it’s only fair.

  • So, basically, it would be incredibly difficult and possibly harmful to kill all the mosquitoes.

  • But we may soon be able to focus on certain species and take away their ability to infect

  • us, making the world a lot safer.

  • But... not any less itchy.

  • Thanks for watching this episode of SciShow News.

  • Thank you to all of the people doing this amazing research.

  • And thank you to our patrons on Patreon who support SciShow so it can always be freely

  • available to everyone.

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Mosquitoes suck. And not just literally, their bites are also itchy and annoying, and certain

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What If We Killed All the Mosquitoes?

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