California could be releasing billions of genetically modified male mosquitoes to fight diseases

The genetically modified insects will be non-biting males engineered to only produce more male offspring

Johanna Chisholm
Monday 11 April 2022 14:15 BST
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The future is decidedly not female for California mosquitoes, or at least that’s what researchers hope to achieve when they unleash up to 2.4 billion genetically altered males into the West Coast state starting this summer in an attempt to control the booming populations.

The Environmental Protection Agency announced last month that biotech firm Oxitec had received approval to expand its existing pilot program in Florida into California’s Central Valley, a campaign that would run through 2024 and release a maximum of 2.4 billion over that time span.

Since male mosquitoes don’t bite, the logic would hold that by expanding the share of male offspring born each season, it would decrease the chances of female biting mosquitoes from spreading deadly diseases like Zika, dengue and yellow fever.

To achieve this effect, researchers at Oxitec paired a special protein to the male so that when it mates with a biting female, the only viable offspring that results are more non-biting males.

Though this campaign could impact all species of mosquitoes, the targeted group is the Aedes aegypti mosquito, a dangerous invasive species that has seen its numbers rise in recent years in the west coast state.

In 2013, the Greater LA County District only had a small concentration of these ankle biters, which are said to be capable of piercing through clothing and laying their eggs in a bottle-cap amount of water. By 2020, the Los Angeles Times reported, that concentration had ballooned to encompass the entire district.

And while California has not yet noted an uptick in the diseases the pests are capable of spreading, there is growing concern since they have the potential and with an out of control population growth, those risks will only become greater.

In a statement from Oxitec’s CEO issued after the announcement of the pilot’s expansion to California, he expressed how “proud” he and his team were to have met this “milestone”.

“Given the growing health threat this mosquito poses across the U.S., we’re working to make this technology available and accessible,” Grey Frandsen said in the statement.

For California, the climate crisis has presented innumerable challenges, wildfires, droughts, intensified storms to name a few. But the warming planet also poses a problem for maintaining the populations of invasive species, such as these vampiric blood suckers, that have taken hold in recent years.

Droughts make for low lying water in pipes and lakes, which in turn make for an ideal breeding ground for mosquitoes. While the lack of rain makes it so more of those eggs don’t get washed away.

Though the project has been approved by the EPA, it’s still awaiting a final sign-off from California’s department of pesticide regulation. And while those who created the genetically modified insects are, as CEO Frandsen says, “looking forward” to “demonstrating the technology”, there are critics who believe there has not been enough transparency and the risks of introducing this new species far outweigh the pros.

The results from the first Florida pilot trial, for instance, have yet to be released to the public, raising concerns about the project’s actual success.

An Oxitec spokesperson noted that findings from the study, which has been discussed online, are set to be released to the public “once all monitoring and assessments are completed”.

When the EPA announced the expansion of the Florida project to California this year, the agency received 13,000 comments in opposition, most of which were collected by the environmental organisations like Friends of the Earth, the Institute for Responsible Tech and the Center for Food Safety.

In reporting from The Guardian, Dana Perls, a program manager with Friends of the Earth of the trial in Florida, explained how the opposition to the mosquitoes being released without more trials comes from a well earned place.

“The public is being asked to trust that Oxitec’s experiment will work and no GE female mosquitoes will survive. But how do we know that?” Ms Perls told The Guardian.

Ms Perls’s concern, along with other critics of Oxitec’s California campaign, point out that there is an antibiotic that is commonly used in agriculture, which California just so happens to be a hotbed for, that can reverse Oxitec’s genetic intervention and actually allow for female’s to be bred.

Tetracycline, the antibiotic, is often found in places where mosquitoes like to nest, specifically wastewater. They’re fear is that, should these genetically modified mosquitoes then interact with this wastewater, the results could lead to a hybrid that scientists cannot account for what the end result would be, but ultimately could lead to the population becoming even more difficult to control.

An Oxitec spokesperson, however, clarified that the EPA has assessed the possibility of a wild female mating with one of the genetically alterned males, specifically when it is in the presence of “sufficient tetracycline” to allow female mosquito survival, noting that their findings included “several lines of evidence” that support that the risk of a hybrid female emerging in “the environment due to high levels of tetracycline is low”.

The EPA also outlined that the critters are not permitted to be released within 500 metres of sources, specifically wastewater treatment facilities, that could contain the antibiotic.

That is not a guarantee that the insects won’t, however, make their way to one of these facilities.

As Mary-Joy Coburn, director of communications for the Greater LA County Vector Control District, told the Los Angeles Times last year, these mosquitoes might not be able to fly far, but they are “smart”.

In an anecdote she shared with the outlet, she described how a female mosquito could very easily hop in your car and lay her eggs in the next city you drop her off in, while others might simply hop over fences and into their neighbour’s yard.

Clarification: An earlier version of this article did not contain the findings from the EPA summary on the possible interactions between the genetically altered mosquitoes and tetracycline in the environment.

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