Mosquito eggs planted in the Florida Keys are expected to hatch tens of thousands of genetically engineered mosquitoes this week, marking the first time such insects have been released in the wild in the United States.
The eggs were provided in late April by Oxitec, a biotechnology company, as part of a federally permitted project to investigate the use of genetic engineering, instead of pesticides, to reduce disease-carrying mosquito populations. The action is aimed against an invasive species known as Aedes aegypti, which spreads illnesses including Zika, dengue, chikungunya, yellow fever, and others, some of which are on the rise in Florida.
The experiment is based on a genetic change that will cause a substantial proportion of future kids to die. Male mosquitos have been genetically engineered to carry a gene that renders their female offspring reliant on the antibiotic tetracycline and hence doomed to fail in the wild. Female numbers are decreased, and the population is reduced as the mating cycle continues over generations. Because the transformed insects eventually die off, this method is self-contained.
Before receiving approval from US Food and Drug Administration in 2016 and the Environmental Protection Agency in 2020, Oxitec had to overcome considerable regulatory barriers. If the present trial program is successful, the company plans to release up to 20 million extra male mosquitos during the peak mosquito season in Florida later this year. The experiment’s findings may one day be used to answer concerns about releasing genetically modified creatures into the wild.
Scientific American met with Omar Akbari, a molecular scientist. His lab focuses on genetic control technologies at the University of California, San Diego, to discover more about the dangers and benefits of Florida’s entry into bioengineered pest management. He’s also a co-founder of Agragene, a biotech firm that uses genetically altered agricultural pests to combat biological problems.
Do you believe the Aedes aegypti trial in the Florida Keys will help prevent mosquito-borne illnesses from spreading?
Insecticides are now being used to suppress this species, although they are ineffective. Resistance has been seen in the field, indicating that new technologies are required.
Other countries have explored Oxitec’s method for releasing genetically engineered insects. In several of their publications, [the business] claims to have suppressed the Aedes aegypti population by more than 90%, including effective control of the Aedes aegypti population in Brazil. The trial in the Keys is anticipated to work and lower Aedes aegypti numbers, based on the previous testing. And, perhaps, it will have a direct epidemiological impact, reducing disease transmission effectively.
Is this technology safe?
It’s completely risk-free. The EPA has done its homework and tested several of the technology’s possible adverse effects. What is the fundamental question here? What are the existing control systems in place? In Florida, several different broad-spectrum pesticides have been used to suppress this mosquito, including pyrethroids, which also kill honeybees, ladybugs, dragonflies, and other insects.
During the 2016 Zika virus epidemic in Florida, aerial spraying of pesticides from planes was seen above communities. Oxitec’s technology, on the other hand, is exceedingly safe. It’ll only kill Aedes aegypti mosquitos, and you’ll use the mosquito to manage the mosquito.
Is the ecology in jeopardy?
It’s a common misperception that this method can eliminate all mosquitos. Mosquitoes are found in about 3,500 distinct species on the planet. Only a few of them are disease carriers. Oxitec’s goal isn’t to eradicate all mosquitos.
[The corporation is] eradicating one mosquito species from a confined population to prevent disease transmission to people. And this mosquito species, Aedes aegypti, is invasive and serves no use in this ecosystem. As a result, I don’t believe that eliminating the species from the habitat would have any detrimental environmental consequences.
Do you see Oxitec’s technology being used in other states in the future?
It is now only permitted to release mosquito eggs in that one area of Florida. It’s legal to use for research purposes in this country. Furthermore, the technology is regionalized. These mosquitoes don’t have much range.
The success of the present experiment in Florida will be the first criterion for using the technology in other places. After that, Oxitec can request additional licenses to conduct more significant releases in other locations.
If that happens, the situation will be the same as what happened in Florida. I believe [Oxitec] would coordinate releases with local mosquito-control districts in such areas and track the density of the Aedes aegypti female population over time. Obtaining permission in other regions may need placing it on a vote to allow the people to weigh in on the choice as Florida did.
What are the potential drawbacks of this strategy of reducing disease-carrying mosquitos?
Scalability is one concern. Can they scale this technology to remove this pest from all of America’s states where it’s found, which is roughly half of the country? Is it just applicable in small towns? And, if they do scale it, what is the cost of doing so?
Furthermore, species-specific technology has two sides. On the one hand, you’re just going for one type of animal.
Multiple species, on the other hand, are frequently involved in the transmission of disease. In Brazil, for example, two distinct species transmit the dengue virus: Aedes aegypti and Aedes albopictus. This is also true in Florida. So even if you get rid of one of them, the other remains.
How likely is it that other places will follow the Florida Keys mosquito district’s lead due to global warming?
Some people have done so already. The Cayman Islands and Panama have granted Oxitec permission to unleash their modified Aedes aegypti mosquitos. In India, genetically engineered mosquitos are released into cages containing wild-type mosquitos to mate, and the results are compared to cages without the modified bug. Releases have been made in Malaysia and Australia by others. And, as more success stories emerge, more governments will be eager to adopt this technology, given that the prices are reasonable.
The livable range of Aedes aegypti mosquitoes is growing as a result of global warming. The species is currently found in several states across the United States when it was not ten years ago. This, too, will become increasingly essential as this mosquito species and its illnesses become more common.
What biological pest-control methods are you developing at the moment?
A [preprint] publication from our lab is presently being reviewed, and it describes a new CRISPR-based method that may be used to eradicate Aedes aegypti populations. It’s also self-restrictive. We’re enthusiastic about this since we were able to remove people in laboratory cages altogether. And we believe this is a next-generation technique that can be utilized in conjunction with Oxitec technology. The result is relatively similar.
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