A project that will see the release of 750 million genetically modified mosquitoes in the Florida Keys has been approved, but not without debate, criticism and allegations of a “Jurassic Park experiment.” Last week, the board of the Florida Keys Mosquito Control District (FKMCD) approved the proposal by Oxitec, Ltd., to release millions of male, genetically altered mosquitoes.
The Aedes aegypti mosquito is an invasive species found throughout the world—including the Florida Keys—that spreads diseases such as dengue, yellow fever, Zika and chikungunya. However, it is only the females in the species that bite humans and spread disease. Thus, Oxitec, a U.K.-based company, has modified male Aedes aegypti at the genetic level to only provide live male offspring when mating with a female in the wild. With female offspring unable to survive, the population of insects that transmit disease would greatly reduce—theoretically, at least.
Oxitec representatives say the company has successfully completed projects in the Cayman Islands and Brazil, releasing more than a billion of their mosquitoes over the years with no risk to the environment or humans. They also point to multiple studies from government agencies, including the EPA and CDC, that say the project is safe. However, scientific experts have questioned the validity of these studies, instead pointing to a 2019 study that examined the negative effect of Oxitec’s mosquitoes in Brazil.
For two years, 450,000 GM, male mosquitoes were released every week in Jacobina, Brazil. When the researchers sampled the population at the end of the release, they didn’t find all male, non-biting mosquitoes as intended; rather, they found hybrid GM-wild mosquitoes.
“Evidently, rare viable hybrid offspring between the release strain and the Jacobina population are sufficiently robust to be able to reproduce in nature. The release strain was developed using a strain originally from Cuba, then outcrossed to a Mexican population. Thus, Jacobina Aedes aegypti are now a mix of three populations. It is unclear how this may affect disease transmission or affect other efforts to control these dangerous vectors,” the authors concluded in the paper published in Scientific Reports.
That’s enough to give scientists pause, and the public seems overwhelmingly unconvinced as well. An EPA public comment period raised many questions and concerns among Florida Keys residents and others, including:
- Toxicity/allergenicity of the engineered proteins in the male mosquitoes
- Possible increase in antibiotic resistance in the environment
- Effects on food supply for insects, animals and humans
- Potential for disease transmission from GM mosquitoes, and more.
Oxitec says they have addressed all concerns, but experts say that’s nearly impossible.
“An ecosystem is so complicated and involves so many species, it would be almost impossible to test them all in advance in a lab,” Max Moreno, an expert in mosquito-borne diseases at Indiana University who is not involved in the company or the pilot project, recently told the Associated Press.
Still, FKMCD board members, of which four approved the project and one dissented, say they feel as if they have no choice as Aedes aegypti has developed a tolerance for many of the area’s pesticides, making them less effective.
“Any approved tools that show promise in helping control this dangerous mosquito are worth examining to the fullest extent. We look forward to working with Oxitec and carrying out this trial as it has the potential to increase effective mosquito control in the rest of the United States,” said Andrea Leal, Executive Director of the FKMCD.
Photo: Adult female Aedes aegypti. Credit: James Gathany, CDC