Mosquitoes have long been associated with the spread of diseases like malaria, dengue fever and the Zika virus. But scientists around the world have been exploring the possibility that mosquitoes could also be key to slowing the spread of disease.
By genetically altering the DNA of mosquitoes, scientists hope to prevent them from passing on pathogens to humans and, therefore, control the spread of vector-borne diseases.
To some, it is an exciting opportunity that could open up new possibilities in the fight against endemic diseases. But the practice has also raised questions from some in the scientific and environmental communities about the impact on local ecosystems, and the ripple effects such modifications could have on the mosquito populations themselves.
Two years ago in the town of Bana, about a four-hour drive from the capital of Burkina Faso, researchers released thousands of genetically modified mosquitoes. Dusted with a neon powder, the tiny insects resembled fireflies as they took to the night skies in western Africa.
The mosquitoes were Anopheles gambiae, a potential carrier of the parasites that cause malaria. However, these male mosquitoes could not reproduce. Moreover, there was no danger they would contribute to the spread of malaria, as male mosquitoes lack the mouthparts to bite.
About a month after their release, researchers had the herculean task of finding and gathering every neon-painted mosquito that had been released.
Scientists with the research consortium Target Malaria believe such genetically altered mosquitoes could become a powerful weapon in the fight against malaria – a disease that kills nearly half a million Africans a year. Burkina Faso alone accounts for four per cent of malaria-related deaths, according to the World Health Organization (WHO).
The West African country has been a testing ground in recent years for biotechnology such as genetically engineered mosquitoes. However, it is not the only country looking to genetically modified mosquitoes as a possible solution to stop the spread of disease.
Yet laws regulating genetically engineered species aren’t consistent between countries. And experts say there’s a growing need to fix that.
“It’s a turning point. There’ll be a lot more interventions coming and the way that decisions are made now related to consent and transparency are extremely important as the 21st century progresses,” says Kerry Bowman, a bioethicist at the University of Toronto.
The United States has been grappling with questions about how to regulate genetically modified mosquitoes for more than a decade, since the Florida Keys Mosquito Control District (FKMCD) and U.K.-based company Oxitec started discussing the possibility of releasing genetically engineered mosquitoes.
The FKMCD was looking for a new tool in the fight against dengue fever and other vector-borne diseases.
A framework does exist in the U.S. for regulating biotechnology, with the responsibility for regulating genetically modified organisms shared between three federal agencies: the Animal and Plant Health Inspection Service (APHIS), the U.S. Food and Drug Administration (FDA) and the U.S. Environmental Protection Agency (EPA).
But when Florida authorities started talking about releasing Oxitec’s “Friendly” mosquitoes in the Keys, it wasn’t clear which agency should take the lead.
“The technology was new enough that when the conversations began back in the middle part of the decade, it wasn’t really known exactly whose basket it fell into,” explains Chad Huff, public information officer with the Florida Keys Mosquito Control District.
Initially, the FDA regulated the project, releasing an environmental assessment in 2016, before the EPA eventually took over regulatory control.
Some environmental activists in the Keys say the EPA didn’t adequately assess the potential risks from the Oxitec mosquito, and suggest the agency made a mistake in regulating them under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA).
“It’s not an insecticide either; it’s an animal – and it’s an animal that you have genetically modified, but yet have neglected to understand all the evolutionary outcomes,” says Barry Wray, executive director of the Florida Keys Environmental Coalition.
Oxitec injects its Aedes aegypti mosquito eggs with a “lethal gene” that prevents females from being born and a fluorescent marker. And the EPA found the danger was so remote that females would be released that it didn’t “make a determination of the allergic or toxic potential” of the “lethality gene” or fluorescent marker.
Wray has harsh words for the EPA, telling the agency that in failing to investigate even a remote possibility that females will survive, “you’ve basically neglected your responsibilities as a regulatory agency.”
Oxitec and the Florida Keys Mosquito Control District say they’ve undergone years of “rigorous” vetting of the technology, and that they’ve agreed to suspend the process if any female mosquitoes are detected. Oxitec also says the impact on the ecosystem would be minimal and that insects like bees and butterflies would not be affected.
But it’s not enough for environmental activists, who are calling for greater transparency and accountability.
“Put yourself in a picture where we’ve lowered the bar for regulation. We haven’t looked very hard… and they get approval to release this mosquito. Let’s say they get commercial approval after that, which isn’t too far behind,” says Wray.
“And we end up with a morass of these different species out in the wild. And Oxitec won’t be the only company; there will be other companies. And what do we have now? We have unknown risk,” he adds.
In Burkina Faso, researchers with Target Malaria have evaluated the data from the initial release of sterile male mosquitoes two years ago, and laboratory partners are now working on a mosquito that can reproduce – with only males surviving.
The West African country has helped pave the way for biosafety legislation on the continent, establishing the National Biosafety Agency in 2005, and introducing a biosafety law a year later (amended in 2012) as it prepared to begin cultivating Monsanto’s genetically modified cotton.
The goal is eventually to release “gene drive” mosquitoes, which would allow a gene to pass through generations of pests and ultimately lead to a population that is predominantly male, or where the females are sterile.
Heather Coatsworth, a postdoctoral fellow at the University of Florida, studies the bioengineering of mosquitoes and says regulation of gene drive technologies is often determined on a “country-by-country basis.”
But in Africa, the New Partnership for Africa’s Development (NEPAD) is working with countries like Burkina Faso, Mali and Benin to develop a pan-West African framework.
“It’s clear that neighbouring countries also are going to be involved. Because if you release your gene drive mosquitoes, basically it means that they might cross the border and then go to other countries,” says Abdoulaye Diabaté, principal investigator for Target Malaria.
But the experiment in Burkina Faso is also facing opposition, from activists like Ali Tapsoba.
“We have never done a national survey for this project, in my country. You will see that we have organized marches where we have mobilized several hundred organizations that are against this project. This project is controversial,” says Tapsoba, who is president of the organization Terre à Vie
In Canada, genetically engineered mosquitoes, whether they include “gene drive” technology or not, would be regulated under the Pest Control Products Act. But Health Canada says there are no plans to release such technology currently.
With the release of genetically engineered mosquitoes still in the experimental phase, we’re still a long way off from determining whether they would even be effective as a weapon against disease.
But experts say they’re seeing decreasing effectiveness with regular pest control methods, and some are pinning their hopes on biotechnology.