Can CRISPR-Cas9 Technology End Mosquitoes and Should We?

[Ygggdrasil]

Mosquitoes are responsible for spreading a number of human diseases (including malaria, Dengue fever, and Zika virus), and account for nearly half a million deaths per year worldwide. For many years, scientists have been investigating technologies that could help control or even eliminate mosquito populations, and CRISPR-Cas9 technology offers a potentially powerful approach to eliminate mosquitos: gene drives.

Genes normally have a 50-50 chance of being passed from parents to children, but gene drives are genetic elements designed to be passed from parents to children at a near 100% rate. This enables a gene drive (and the other genes that it carries) to very rapidly spread throughout an interbreding population, essentially giving scientists the ability to genetically modify all individuals in that population. See this physics forum thread from a few years ago on the subject: https://www.physicsforums.com/threads/gene-drives-how-to-genetically-modify-an-ecosystem.762289/

Now, scientists provided the first demonstration that, in a controlled laboratory setting, gene drive technology could be used to eradicate a population of mosquitoes:

For the first time, scientists have demonstrated that a controversial new kind of genetic engineering can rapidly spread a self-destructive genetic modification through a complex species.

The scientists used the revolutionary gene-editing tool known as https://www.broadinstitute.org/what-broad/areas-focus/project-spotlight/questions-and-answers-about-CRISPR to engineer mosquitoes with a "https://wyss.harvard.edu/staticfiles/newsroom/pressreleases/Gene%20drives%20FAQ%20FINAL.pdf which rapidly transmitted a sterilizing mutation through other members of the mosquito's species.

After mosquitoes carrying the mutation were released into cages filled with unmodified mosquitoes in a high-security basement laboratory in London, virtually all of the insects were wiped out, according to a report in Nature Biotechnology.

https://www.npr.org/sections/goatsa...odified-to-crash-species-that-spreads-malaria

Here's the associated paper:
Kyrou et al. A CRISPR–Cas9 gene drive targeting doublesex causes complete population suppression in caged Anopheles gambiae mosquitoes. Nat Biotech. Published online 24 Sep 1028

Abstract:
In the human malaria vector Anopheles gambiae, the gene doublesex(Agdsx) encodes two alternatively spliced transcripts, dsx-female(AgdsxF) and dsx-male (AgdsxM), that control differentiation of the two sexes. The female transcript, unlike the male, contains an exon (exon 5) whose sequence is highly conserved in all Anopheles mosquitoes so far analyzed. We found that CRISPR–Cas9-targeted disruption of the intron 4–exon 5 boundary aimed at blocking the formation of functional AgdsxF did not affect male development or fertility, whereas females homozygous for the disrupted allele showed an intersex phenotype and complete sterility. A CRISPR–Cas9 gene drive construct targeting this same sequence spread rapidly in caged mosquitoes, reaching 100% prevalence within 7–11 generations while progressively reducing egg production to the point of total population collapse. Owing to functional constraint of the target sequence, no selection of alleles resistant to the gene drive occurred in these laboratory experiments. Cas9-resistant variants arose in each generation at the target site but did not block the spread of the drive.

https://www.nature.com/articles/nbt.4245

So, it appears we may be at the cusp of having the technology to completely eradicate mosquitoes. The question is: should we?

 

[berkeman]

Wonderful news! I vote yes.

For most animals and plants, we can find a reason not to eliminate them. They often have some overlooked useful contribution to the overall ecosystem (I hate great white sharks because I'm a diver, but I can see that eliminating them could be a bad thing overall). Do mosquitoes serve any useful function? They are food for birds and some other animals, but would other less-dangerous insects fill in the void after we wipe their ugly stinger faces off the face of the Earth?

 

[Bystander]

Possible drawbacks? "The unintended consequences," to be named at a later date, "It's not nice to 'fool' with Ma Nature." Any survivors are going to be real terrors.

 

[BillTre]

I find it interesting that the disease carrying mosquitos (of the Anopheles genus) are invasive in the new world. They are native to Africa I believe.
This should simplify any decision about the effect eliminating them would have in North or South America, since they have only been there for a relatively short time and could presumably be eliminated without too much disturbance to the environment.

Native mosquitos would raise more questions.

 

[Bandersnatch]

Ha! Good riddance, suckers!

 

[256bits]

Economic insanity!
A great many businesses and people depend upon mosquitoes for their livelihood.
Mosquito nets, zappers, repellent, itch cream, sprayers, medical industry, just a short list I guess.

Not to mention all the animated discussions about these buzzing insects at the outdoors;
And the buzz of just one at night that just won't let you fall asleep as you wait for the silence and the coming itch - gone forever, only a memory soon to be forgot?
Will "progress" trump tradition?

I say not.
Let the young people enjoy the pleasure of recounting tales of fighting the ever menacing Mosquito?

 

[Rive]

The question is: should we?

I think science is still some decades (centuries?) away from being able to answer that question.

I wonder if this technology would be able to make a population of mosquitoes incompatible with specific diseases? That would make it a far less problematic question.

 

[DrClaude]

So, it appears we may be at the cusp of having the technology to completely eradicate mosquitoes. The question is: should we?

That's a rhetorical question, right? RIGHT?

 

[Drakkith]

Another question is where do you draw the line between organisms that you exterminate vs those that you don't? For example we have completely eradicated two different diseases, and now we're thinking about eradicating the vector of many nasty diseases. Would it be better to take the 'easy' route and eliminate the vector (mosquitoes or other vectors), or the much more difficult route of eliminating the diseases themselves one at a time?

 

[Ratman]

Jokes aside, mosquitos and their larvae are important food source for many animals. If the question was stated: "would you like to have less fish, songbirds and waterfowl", less people would be likely to suport that. In some places they can also be important pollinators. But I agree that eliminating vector species may be a good idea – after some time they would simply be replaced with other insect species. Eliminating vector will also help eradicate the disease, and easier, cheaper option will get more suport from decision makers.

 

[pinball1970]

I think it’s worth the risks to the rest of the food chain to get rid of this animal.

 

[berkeman]

Do mosquitoes serve any useful function?

Whelp, looks like we have to put the brakes on eliminating mosquitos. Sigh...

https://abc7news.com/mosquitoes-force-suspect-to-surrender-in-wisconsin/4327344/

 

[sysprog]

Why stop at the mosquito? Biting black flies come to mind. ... "I've got a little list"...