EPA approves field trials of genetically modified mosquito

July 12, 2020

By Adam Wernick

Genetically modified mosquiito — Oxitec’s second-generation “AA” friendly mosquitoes are genetically engineered so that all female offspring die at the larval stage. The females are the ones that bite and spread disease from their saliva.
Courtesy of Oxitec Ltd.

The Environmental Protection Agency has given biotech company Oxitec the go-ahead to test the effectiveness of genetically modified mosquitoes in parts of Florida and Texas.

Oxitec has been developing genetically modified mosquitoes in hopes of reducing local populations of mosquitoes that carry dengue fever, yellow fever and the Zika virus. About 750,000 people die each year from mosquito-borne illnesses, making the insect indirectly responsible for more human deaths than any other animal in the world.

Oxitec plans to target a particular mosquito called Aedes aegypti. The company hopes introducing the genetically engineered version of this mosquito will reduce its overall population and lessen the need for ecologically damaging pesticides.

The EPA approval is controversial and has received pushback from ethicists and molecular biologists, including Natalie Kofler, founding director of Editing Nature, a working group on the ethics of genetic modification and an advisor for the Scientific Citizenship Initiative at Harvard Medical School.

“This is really a landmark decision. It’s the first time a genetically modified mosquito has been approved for release in the United States.”
Natlie Kofler, founding director of Editing Nature

“This is really a landmark decision,” Kofler says. “It’s the first time a genetically modified mosquito has been approved for release in the United States.”

Oxitec had attempted to get approval to conduct field trials in 2016 and 2017, Kofler notes, but eventually rescinded their request because of public pushback from the communities in Florida where they planned to release their mosquito. “So, this is their second attempt at doing this, and it’s something that we’re watching really, really closely to make sure that this moves forward in a responsible way.”

Oxitec engineered its new Aedes aegypti mosquito by introducing a gene that causes all of its female offspring to die at the larval stage. “Over time, as you can imagine, if there aren’t females around, the population will collapse,” Kofler explains. “The intention is to reduce local mosquito populations and, in doing that, be able to then reduce transmission of the diseases they carry.”

The resistance of the Florida communities grew out of concern over being the first test site in the US to have a genetically modified organism released into their common environment, Kofler says.

“There’s no way to do these field trials in a contained way,” she notes. “The mosquitoes are literally sent out into the air and fly around [and] mate with other wild mosquitoes. So people had a variety of concerns, both for their own health as well as for the health of the environment.”

Oxitec hopes to mitigate some of the health concerns by exclusively releasing only male mosquitoes, which do not bite. But environmental concerns remain, Kofler says.

“What happens when you start collapsing populations in the wild in this way,” she asks. “I think that’s really the main [reason] why people have a lot of concerns. We just don’t know enough yet about how this would work in the wild.”

Oxitec has been releasing versions of these mosquitoes for over a decade in Brazil and other countries in South America. So far, Kofler says, the data seem to indicate that they do reduce the population, but the company has yet to prove any reduction in Dengue fever transmission.

Kofler also remains concerned by the lack of stringent studies and data on the ecosystem and health impacts. A third concern, and a “really major one,” she adds, is that a lot of the data presented to the EPA was accumulated and assessed during experiments designed by Oxitec itself.

“I’m concerned that there’s not enough independent oversight. I’m concerned that there’s not enough interdisciplinary oversight,” Kofler says. “These are really complex decisions that are being made. You need to have ecologists, you need to have public health experts, you need to have vector biologists, you need to have ethicists and geneticists all at the table to make these choices.”

“And of course, it’s also concerning when it’s a for-profit company,” Kofler adds. “In some ways, they have a lot of vested interest in making sure that they do this well and safely because they could lose a lot of money, and they could lose trust in their product. But at the same time, it leads to a lot of opacity in this process. … There are a lot of parts of the EPA submission that the public is generally not allowed to access because it’s under patent protection and things like that.”

There’s also a “really strong” environmental justice argument to be made, Kofler continues. People have the right to be involved in decisions about the release of genetically modified mosquitoes into their communities, she insists, “and right now our regulatory processes do not engage the public even close to the level that they should be to make these choices fairly.”

If Oxitec’s plan is done safely, Kofler notes, it could be a more environmentally responsible measure than doing a broad application of pesticide, for example. But there’s still a lot of uncertainty.

“What happens when you specifically target one vector of a disease,” she asks. “Is another vector going to step in, another mosquito species that may be more difficult to control, that might be even more able to spread the disease more easily and be more virulent? And these are really major concerns that we still don’t have have the answers to.”

This article is based on an interview by Bobby Bascomb that aired on Living on Earth from PRX.