Mosquitoes are more than just a nuisance. Through the transmission of disease, they kill more people than any other animal, earning them the title of deadliest organism on the planet.
We’ve tried many ways to keep them away and kill them but nothing has worked completely.
But now we might have the means to kill them all — to actually make them extinct.
The last mosquito on earth is born this way.
Three days after the egg is laid, the larva emerges
Its childhood is spent on the surface of a stagnant puddle and it lasts the entirety of a week.
If it’s male, he whiles a way his days feeding on flowers before succumbing to old age within a few days.
If it’s female, she will have an entire month to gorge herself on the blood of nearby vertebrates.
Either way, the mosquito will be extinct within a matter of weeks.
It will take with it not only the capacity to spread death and disease amongst its vertebrate prey but the secret to its own demise.
Buried deep within the genetic code of that last mosquito is a gene that renders the organism sterile.
This deadly heirloom only appeared in her species a few years before, placed their by her vertebrate prey.
Only a tiny fraction of the population even harbored this gene at first.
But these first of the last mosquitos weren’t born in a puddle or a swampy marsh.
They came to be in the confines of a laboratory somewhere, conceived in petri dishes and engineered by scientists.
Each one won’t look any different than any other member of its species.
But each one will harbor a gene so insidious that within a few dozen generations the entire population will be as sterile as the laboratory where they were born.
Their vertebrate prey — especially a certain superabundant primate — have shown an uncommon ingenuity when it comes to thwarting their mosquito predators.
And we have good reason.
Through the transmission of disease, mosquitos kill over a million people every year, earning them the distinction of deadliest organism on the planet.
We have deployed chemical repellants and insecticides on grand scales. Drained their nurseries and habitats, and introduced natural predators to control the mosquito population.
But nothing completely eliminated the mosquito.
But now we might finally have the technology to eradicate the mosquito.
Thanks to Crispr.
Crispr is a gene editing technique that allows us to make changes to DNA with surgical precision. The technique was first developed in the late 1980s but has become more and more commonplace in the last few years. With it we could remove genes that cause disease or remove undesirable characteristics or we could insert specially tailored genes to cultivate whatever traits we want.
Even harmful traits.
It’s hard to overestimate the power of Crispr.
It could help eliminate diseases that have plagued humanity since the beginning of time.
But that only works if a gene specifically codes for a disease. If the disease is spread through — say — the bite of mosquito, that approach would be ineffective.
But instead of removing the gene that caused the disease, we could use Crispr to remove the entire species responsible for the spread of the disease using a technique called a gene drive.
This is how it works.
Insert a gene into a mosquito that renders the species less fit to survive. In this case, a gene that makes the mosquito sterile.
Since the mom and dad mosquito are only contributing 50% of their genome to the next generation, any given a gene in a single organism will have a 50% chance of being passed on. But a gene drive increases the chance of transmission so that even though a gene might have a deleterious side effect — like sterility — the gene drive keeps the gene in the population at higher than expected rates.
The gene’s presence keeps increasing with each successive generation until most — if not all — mosquitoes are sterile.
And once an organism can’t reproduce, extinction is imminent.
We could do this to the mosquito. And since mosquitoes go through a dozen generations per year, the gene would quickly propagate throughout the entire species.
Until every individual was sterile.
Within a couple years, the deadliest organism on the planet would be extinct.
Nobody has done this yet. But that doesn’t mean they aren’t trying.
As a proof of concept, researchers successfully used a gene drive to change the dominant color of a species of fruit fly to yellow.
It took only two researchers working on their own to make this possible.
A lab at Imperial College London is in the process of crafting one of these self-defeating mosquitos. And a half dozen other research institutions are working toward the same goal.
These genetically modified mosquitos already exist in laboratories. Whether we release them into the wild — whether on purpose or by accident — might be only a matter of time.
But this technology isn’t limited to mosquitos. Any species with a fast reproductive cycle could be a candidate for the gene drive.
Vampire bats could be targeted with gene drive techniques to reduce the transmission of rabies.
In 2017, the New Zealand government announced that it would pursue gene drive technology to eliminate eight invasive mammalian species from their island. Rats, possums, and stoats were all introduced to New Zealand accidentally through shipping and migration. Their presence has wreaked havoc on the fragile ecosystem, pushing native species to the brink of extinction. Gene drive techniques could eliminate or drastically reduce the populations of these invasive predators by 2050.
But mosquitos are not an invasive species.
For all the death they cause, they fulfill a role in the ecosystem. The males act as pollinators for flowering species and we can’t remove the deadly females without also removing the males. It’s hard to predict what exactly would happen if the mosquito disappeared from the ecosystem. Another species would probably fill the void left by the mosquito. Which one is hard to say and it’s entirely possible the mosquito could be replaced by an even more deadly and pervasive disease vector.
Or the gene drive could jump species, leading to the unintended extinction of a whole other organism.
Or a natural mutation could render the gene drive ineffective, possibly creating an mosquito population even more resistant to our eradication efforts.
Then again, maybe nothing at all would happen.
The scientific genus of the mosquito that transmits Malaria is Anopheles. In Greek this literally means ‘useless.’
But the inherent ecological value of a species — even one as deadly and seemingly expendable as the mosquito — is hard to estimate.
We have no qualms eradicating small pox. No one is lamenting the demise of the guinea worm. Should we feel guilty for causing the extinction of the deadliest organism on the planet?
Extinction is a natural process.
99% of all life that has ever existed is now extinct and every species eventually dies out.
This certainly isn’t the first time we have caused the extinction of an entire species. The dodo, the passenger pigeon, the Tasmanian Tiger, and a dozen other species have all disappeared because of our actions. We are in the middle of one of the greatest mass extinction events in the history of the planet.
And it is being perpetrated by us.
Overhunting, habitat-loss, climate change, and our generally reckless and thoughtless behavior have all contributed to this mass extinction. It is the result of our mistakes. But for the first time ever, our species can make the conscious decision to make another species extinct. And this time it won’t be a mistake.
We’ll have it down to a science.
If we decide to go forward with the extinction of the mosquito, there will be no need to lament the loss of the deadliest organism on the planet. I have no doubt that there is already another species waiting to fill that role.