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In a story I am considering, a company modifies some mosquitoes so all their offspring will be male, and this is passed on to their children. So all ancestors will be male and eventually all the mosquitoes can only have male offspring leading to extinction.

Is this modification at all possible?

What impact would this have on the environment?

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  • $\begingroup$ Hmmm... sounds a lot like the issue in 'Jurrasic Park' "I'm just saying - ' Life Finds a Way..." $\endgroup$
    – Joe
    Aug 10 '17 at 19:56
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Not Likely. More importantly the act of introducing a genetic mutation would be insufficient for a number of reasons.

  1. not one single species of mosquito, but over 3500 described. These mosquitoes are further separated into breeding populations that are separated by geography.
  2. If you were to eliminate one population of one species, All you have done is emptied one environmental niche, which will be rapidly filled by either another adjcent population of the same species of mosquito, a different but similar species of mosquito, or a different species entirely.

It would take a concerted effort, at first to identify and modify mosquitoes of all species, and introduce the modified organisms of the target species into each breeding population, and to backfill the niche with the appropriate, desired, species.

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Yes.

In fact, the technology already exists today. It is called gene drive.

Essentially, a gene drive causes a specific version of a gene (an allele) to always be passed on to offspring. Normally random choice gives each allele only a 50% chance of being passed on. This means that a gene drive allele will spread incredibly rapidly through any population it is introduced to. Current research is focusing on eliminating mosquitoes by making a gene drive allele that is harmless with one copy (heterozygote), but lethal with two copies (homozygote). When a wild mosquito mates with a heterozygote all of the resulting offspring will be heterozygotes. Eventually the entire population will be heterozygotes. When two heterozygotes mate their offspring will all be homozygotes and will die. Thus the entire population will be rendered infertile.

Your idea of an all male population can be achieved by making the homozygotes only die when female, but not when male. In theory this would improve the approach by maximizing the spread of the gene drive allele.

As far as environmental effects go all research I have seen on the subject suggests the extinction of mosquitoes would have only a minimal effect on the ecosystem. This technology and in fact these mosquitoes exist today. The main obstacle to their use is the unstoppable nature of the gene drive. Any unforeseen consequences would be irreversible.

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Something similar is already happening

https://www.cnbc.com/2017/07/11/microsoft-and-other-tech-companies-are-waging-war-on-disease-carrying-mosquitoes.html

Male mosquitoes are being bred that are sterile, when released they mate but produce no offspring thus eventually causing extinction.

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    $\begingroup$ Welcome to WorldBuilding! Please don't write that you are trying to circumvent the system by posting a comment as an answer. If you have a source please edit your answer to summarize its content. That would be a valid answer! Posting a comment as an answer is a reason to flag as "Not an answer" which could lead to your answer being deleted. And comments could be deleted at any point for any reason. If you have a moment please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$
    – Secespitus
    Aug 10 '17 at 14:56
  • $\begingroup$ Thanks, But I would prefer the system to be irreversible once started. $\endgroup$
    – PStag
    Aug 10 '17 at 15:07
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It will be a numbers game. If a female only mates with one partner then with each generation there will be more males and eventually there will be no females.

If a female breeds with 2 males then even if you introduce as many males as the current population only 1/4 of the females would produce a sterile male. You cannot introduce enough to win the war. Or you need super sperm that dominates other sperm.

A male that will kill the female after birth and the female will produce one killer male will work if the female will produce a killer male even if it breeds with other non kill males.

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The idea

Your idea is not new and has been discussed by the scientists. With the discovery of Nix gene in 2015 it has become a possibility as that gene allows to change the sex of the mosquitoes. Currently, the research is being carried out, more to read in the links below.

The consequences

Again, we have some facts to base on, as mosquitoes population is already monitored due to the programs of controlling the number of those insects carried out since the forties. Although mosquitoes are important part of the ecosystem being food for many animals, their eradication shouldn't be a big problem as their niche would probably be filled by some similar insects. Especially since your version of mosquito genocide would be gradual and give the nature a lot of time to react.

Links:

http://science.sciencemag.org/content/348/6240/1268

https://phys.org/news/2016-02-crispr-female-mosquitos.html

http://io9.gizmodo.com/what-if-every-mosquito-on-earth-went-extinct-tomorrow-1646840383 https://www.terminix.com/pest-control/mosquitoes/facts/do-we-need-mosquitoes/

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Yes. The problem with having a genetic disorder for only male offspring is that it doesn't spread through the population very well; the males die off before they can make too much of an impact. However, depending on how advanced the company in your story is, you can have them create a virus. They could make a disease that has an incubation period. A dormant disease can leave the mosquito alive just long enough to spread the infection through more of the population. It could wipe them out the same way diseases have threatened humans throughout history.

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