A daring experiment is underway in the USA: A biotech company releases genetically modified mosquitoes that are intended to mate with wild insects and thus render the population infertile. Local resistance is great.
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By Steve Przybilla
04/24/2022 – 10:18 am
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When Bryon Elliot goes mosquito hunting, he leaves the chemicals in the car for now. Instead, the pest exterminator grabs a landing net and a bucket with silverfish swimming in it. He carefully releases the fish in a rainwater overflow basin. “They’re very useful,” says Elliot, “because they love to eat mosquito larvae.”
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Mosquitoes have always been a problem in Florida, especially in the Florida Keys, an archipelago at the southernmost tip of the country. The yellow fever mosquito, an invasive species from the tropics, is currently spreading particularly rapidly.
In recent years, there have been multiple dengue and Zika virus outbreaks on the Keys because of them. To solve the problem, the authorities have now embarked on a daring experiment: genetically modified mosquitoes. It is the first such large-scale test in the USA.
Mosquitoes become resistant to sprays
“In this fight, we need every tool we can get,” says Andrea Leal, director of the Florida Keys Mosquito Control District. This state authority is responsible for controlling the pests – and that is becoming increasingly difficult: “Many mosquitoes are becoming resistant to our insecticides,” says Andrea Leal. “That’s why we’re grateful for every new drug in our arsenal.” The new drug is – also a mosquito.
The British biotech group Oxitec has released five million genetically modified larvae on the Florida Keys. The resulting mosquitoes will mate with the wild population. The modified genes should help to reduce the mosquito population in the long term – without any danger to people or the environment, Oxitec assures.
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Genetic engineering scares locals
Many locals are not so sure. Next to the Overseas Highway is a poster that local environmental organizations have put up. It shows a giant mosquito stinging a woman’s eye. Caption: “Gene mosquitoes? What can possibly go wrong?” The motif sums up the concerns of the project opponents. “There’s no room for error in experiments like this,” said Ed Russo, president of the Florida Keys Environmental Coalition. Who knows how the gene mosquitoes affect the food chain?
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For years, Russo and his team have fought against the experiment, which they believe to be opaque and dangerous. “I’m not against genetic engineering in general,” says Russo. “In the beginning I was really excited. We thought that no more chemicals would have to be used.” But that turned out to be a fallacy: Yellow fever mosquitoes accounted for only four percent of all mosquitoes on the Keys. Insecticides would still have to be sprayed against all other species – which is also confirmed by the state mosquito control.
Referendum under dubious conditions
The way in which the experiment was pushed through also triggers resentment. Two non-legally binding referendums were held. In the city of Key Haven – the place where the mosquitoes were first to be released – two-thirds of the population voted against the project in 2016. In the end, however, only the vote of the entire district was counted, in which the majority of those surveyed voted for the experiment.
In fact, there are also ardent advocates of GM mosquitoes. For example Doug Mader, who works as a veterinarian on the Keys. Mader has been promoting the project for a long time – “without getting a cent from Oxitec”, as he emphasizes several times. He is particularly concerned about dogs: “The yellow fever mosquito transmits heartworms,” he says. “It’s a very cruel disease.” In addition, the chemicals currently used killed many butterflies and other beneficial insects. That’s why he supports the alternatives.
Also a deployment in Europe conceivable?
The first phase of the project in the Florida Keys, which began with the installation of the larvae boxes in April 2021, is now complete. According to Oxitec, it collected the boxes again. The biotechnology company is now turning its attention to the next goal: large-scale application. The project is to be continued this year; Oxitec has already submitted an application to the environmental authority.
If the experiment is successful in the Keys, the gene mosquitoes could also be approved in other states. In the long term, use in Europe is even conceivable, adapted to the Asian tiger mosquito, for example, an invasive species of mosquito that is spreading in this country.
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