✦ Setting the world’s deadliest animal to self-destruct

✦ Setting the world’s deadliest animal to self-destruct
Image: Alexa Pitt
Image for article titled ✦ Setting the world’s deadliest animal to self-destruct
Image: Alexa Pitt

Hi Quartz members,

The mosquitoes are coming—and then, hopefully, they’re going. This week, UK-based biotech company Oxitec plans to kick off a months-long experiment in which it will release Aedes aegypti mosquitoes in Florida. But these aren’t just any mosquitoes—they contain a gene that, if all goes according to plan, will eventually reduce the population of mosquitoes in these areas.

That’s because these mosquitoes are all male (it’s only the females that bite) and they have a special gene. When females mate with them, only the male offspring survive. Over time, all the female mosquitoes disappear, which means they can no longer reproduce. Bye bye, mosquito family.

This isn’t the first test of genetically modified mosquitoes in the real world, but by the end, proponents hope that the experiment will have demonstrated that the technique can work to eliminate disease-carrying mosquitoes in places plagued by malaria, dengue, and Zika, all without pesticides that could harm helpful native species. Future applications of similar technology could go even farther to preserve human life and protect the environment.

But to do so, researchers won’t just have to prove the science works—they’ll have to get regulators and the public on board, too.

Gene drives: Explain it like I’m 5!

How do you ensure all individual animals in a population carry a special gene? Some scientists have suggested using a gene drive (Oxitec does not use a gene drive). Imagine that a scientist has altered an organism’s DNA so that it has a trait the scientist has deemed desirable. The scientist ensures that the gene is highly heritable, so that it has more than a 50% chance of being passed on to the next generation. As that organism and its offspring reproduce, the desired gene affects a higher proportion of a population. Finally, a few dozen generations after the first gene-carrying individual was introduced, all organisms in a population have the desired gene.

Gene drives happen in nature, as researchers learned when they discovered a specific gene called the P-element in wild fruit fly populations that didn’t exist before 1950. But scientists have really only been able to engineer one themselves in the past few years thanks to the advent of the gene editing enzyme Crispr.

Gene drives also come with a potential downside: Once it’s underway, there may be no way to undo it.

Case study

In April, Oxitec announced the results of a seven-month trial in the Florida Keys, the first open-air study of its technology in the US. Researchers found the result they were looking for: that all females carrying the lethal gene died before they became adults, and that no mosquitoes carrying the gene were found more than 400 meters from the places the mosquitoes were released, Nature reports. Oxitec announced the results in a webinar, and they have not been published in a peer-reviewed study.

This study didn’t address reducing local mosquito populations, or the incidence of disease they carried (there have been a few outbreaks of dengue fever in the area since 2010). The larger study this year, however, will look at these same datapoints as well as “baseline numbers of the invasive Aedes aegypti to measure the effect our male-only releases have on the pest population,” Rajeev Vaidyanathan, director of US operations at Oxitec, tells Quartz via email. 

⚖️ Pros and cons

Proponents say, at scale, such a program would result in:

  • Less mosquito-borne illness
  • Little ecological impact since mosquitoes are not a keystone species
  • Less pesticide use, currently used against mosquitoes, which means better protection of local plants and animals
  • Little or no negative impact on humans as the mosquitoes are safe, quick, and effective

Opponents say:

  • Mosquitoes may not be a keystone species, but other animals do eat them and so eliminating the insects may in fact have an ecological impact
  • There could be unintended consequences, such as a hybrid species or the creation of a new ecological niche that other animals, which carry potentially even more lethal diseases, could move into
  • It takes expensive, large-scale trials to have certainty about safety and efficacy

Survey says

The American public seems so far solidly in the opposed camp. A 2016 study based on a mailed survey found that “a majority of survey respondents did not support use of GM mosquitoes as a mosquito control method,” citing concerns around “human and animal health impacts from the GM mosquitoes, and environmental concerns about potential negative effects on the ecosystem.” A 2017 study found that 80% of the comments submitted to the US Food and Drug Administration about a trial in Florida were negative.

“Those studies were for the US. Other nations have not expressed such negative views,” says Anthony A. James, a molecular biology and biochemistry professor at the University of California, Irvine. Though researchers in Burkina Faso have gone so far as to work with a linguist to survey and educate the public about genetically modified mosquitoes, outreach efforts in the US have been slower going.

What would James say to win over skeptics? “I would suggest that they become familiar or remind themselves of the impact of dengue, Chikungunya, and Zika fever on people. Is it worth it to wait until we have a significant disease problem before doing anything?”

In the decade since Oxitec first started working in the Florida Keys, they have conducted “a range of activities to engage Florida Keys residents where they are,” including media appearances, mailings, and social media posts, notes Meredith Fensom, Oxitec’s head of global public affairs. The work seems to have paid off: “In a 2016 referendum, 31 out of 33 Monroe County precincts, including the majority of those in Key West, voted in support of our project. This broad base of support continues, evidenced by the lengthy waiting lists we have for mosquito box and trap hosts,” Fensom adds.

🔮 Future uses

For now, many researchers are focused on using gene drives to eliminate mosquitoes in the interest of public health. “​​I am most concerned about eliminating the diseases,” James says. “Targeting malaria is the main objective. It is by far the most significant mosquito-borne disease.”

But some in the space are already setting their sights on other disease-carrying animals, such as mice and ticks that carry Lyme disease.

Others envision even more far-reaching applications, such as species conservation (by helping native species become immune to disease or even to the harsher conditions of climate change). Advocates say food could become cheaper and less damaging to the environment if gene drives, not chemicals, got rid of pests.

Whether these ideas come to pass depends on more than whether they’re scientifically possible. It will take regulation as well as outreach efforts to earn public trust.

Keep learning

Gene drives (Quartz Obsession email)

The complete guide to Crispr (Quartz)

US poised to release 2.4bn genetically modified male mosquitoes to battle deadly diseases (The Guardian)

A genetically modified organism could end malaria and save millions of lives — if we decide to use it (Vox)

Genetic engineering to clash with evolution (Quanta Magazine)

The gene drive dilemma (New York Times Magazine)

Sound off

How do you feel about genetically modified mosquitoes?

Great—release them everywhere!

Let’s do a bit more research first

I’m skeptical

In last week’s poll about industrial policy, 50% of respondents supported governments funding more industrial policy, but just R&D and writing the rules for companies. We appreciate a light touch.

Have a pest-free weekend,

—Alex Ossola, membership editor (mosquitoes love her)

One 🧬 Thing

Hollywood hasn’t found a way to talk about gene drives yet, but gene editing is a familiar trope, mostly because it’s easy to imagine how things could go horribly wrong. Just look at Jurassic Park, Gattaca, Rampage, and Luke Cage. Here’s a more complete list.

Correction: This email has been updated with information about Oxitec and its experiment. The experiment will take place in Florida and may expand to California pending necessary approvals. Additionally, this will not be the largest experiment to date—that has taken place in Brazil. Some language has been added to clarify that Oxitec does not rely on gene drives.