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Why GMO Mosquitoes Were Spread to Stop Disease in Florida

Headlines worldwide flashed the news of 750 million genetically engineered mosquitoes that are scheduled to be released in Florida Keys. Yet, this raises concerns over the impact on the ecosystem and the possible environmental risks of this experiment. But according to UNICEF, malaria and other mosquito-borne illnesses kill over one million people and infects around 300-600 million people a year. Most cases of malaria are in children, and they can have long term complications on their growth and development. Could genetically engineered mosquitoes could be a solution to our problems? What are some of the concerns of this technology from the public?

What are the GMO mosquitoes being released in Florida?

During a public hearing on August 18, the UK-based biotechnology company Oxitec received approval from the Mosquito Control District Board of Commissioners to begin their pilot program, which will release 750 million genetically engineered male Aedes aegypti mosquitoes, named OX5034.

The program is intended to reduce the population of Aedes aegypti mosquitoes by preventing the survival of female offspring, as these mosquitoes are genetically engineered to carry a protein that prevents female offspring from surviving to adulthood and biting people.

After mating with a wild female mosquito, all the female offspring will die during the larval stage, while according to the U.S. Environmental Protection Agency (EPA), “The male offspring will survive to become fully functional adults with the same genetic modification, providing multi-generational effectiveness that could ultimately lead to a reduction in Aedes aegypti mosquito populations in the release areas,” consequently reducing the mosquito population and prevalence of mosquito-borne illnesses.

This is because only female mosquitoes bite humans for blood to mature her eggs, which occasionally leads to various diseases, so by lowering the population of female mosquitoes, it will reduce the number of mosquito bites and cases of disease. Male mosquitoes feed on nectar and do not bite people, so the released mosquitoes will not transmit diseases to humans.

“Winning the growing war against disease-spreading mosquitoes will require a new generation of safe, targeted, and sustainable tools for governments and communities alike… Our aim is to empower governments and communities of all sizes to effectively and sustainably control these disease-spreading mosquitoes without harmful impact on the environment and without complex, costly operations.”

Grey Frandsen, CEO of Oxitec

Why do we need GMO mosquitoes?

But why do we need this intervention? Aedes aegypti mosquitoes are known to spread diseases such as Zika, Dengue, yellow fever, and Chikungunya, many of which are dangerous and often deadly. In 2009 and 2010, Aedes aegypti mosquitoes caused outbreaks of Dengue fever in Florida Keys, and public health officials scrambled to control the mosquito population.

One solution was pesticides, but it was often ineffective as their best pesticides only killed 30-50% of the mosquito population, according to Phil Goodman, the district board chairman of Florida Keys Mosquito Control District. Mosquito populations have also surged recently, so officials needed a new way to prevent the disease caused by the prevalence of mosquitoes.

However, while these interventions have been recent, the idea of sterilizing mosquitoes is not. Scientists have considered sterilizing mosquitoes through radiation for decades, but the mosquitoes were too weak to survive the treatment. The discovery of gene editing was revolutionary, and the possibility of reducing the mosquito population through sterilization became a reality. Over a million people die every year of diseases that spread through mosquitoes, and with chemical solutions that are ineffective, sterilization through genetic engineering may be a way to reduce the mosquito population.

What are some of the safety concerns over these mosquitoes?

However, many people have concerns over the safety and impact of releasing millions of genetically engineered mosquitoes into neighborhoods and the community.

More than 236,000 people have signed the petition, and many of them express their concerns about the risk of these genetically modified mosquitoes on the fragile local ecosystem through unintended consequences, such as mutations and the introduction of another species, and lack of testing. According to the petition, Oxitec has not been transparent with the data, and they state, “the Center for Disease Control notes that Oxitec’s trials are not set up to test for disease reduction.” The lack of information available to the public has led to concern about the lack of solid evidence for the safety of the environment and public health.

Another concern regards the risk of antibiotic dependance, as the breeding process for the genetically engineered mosquitoes involves the antibiotic tetracycline, which is put in the water to block the protein that kills the female offspring, allowing the female mosquitoes to survive and reproduce. In the wild, there is no tetracycline in the water, so the female offspring will die. However, the concern is that the use of antibiotics in the growing process may lead to the rise of antibiotic resistant bacteria, but Kevin Gorman, public health entomologist from Oxitec, believes that isn’t likely. Testing sites are required to be at least 500 meters away from places that may release antibiotics, such as sewage plants and citrus orchards, and the current version of mosquitoes are cleaned and free of tetracycline.

Oxitec has released mosquitoes in the Cayman Islands, Panama, and Brazil. Image Source

What other places has Oxitec tested their mosquitoes?

This release will not be the first release in the world, as Oxitec has already tested the previous versions of the mosquitoes in the Cayman Islands, Panama, and Brazil. Oxitec reported that the rate of success was high – it reduced the mosquito population in Brazil by 95%.

However, in September 2019, a study published in Scientific Reports found that the female mosquitoes bred from the released genetically modified mosquitoes in Brazil were not dying off as intended. Yet, after receiving criticism, this study was later found to have faulty study design and misleading claims, so it was issued an Editorial Expression of Concern from the publication.

While the pilot program is designed to reduce the mosquito population, it is unclear what the effect of these genetically engineered mosquitoes will have on the prevalence of disease or impact on predators that eat the mosquito. Nevertheless, Oxitec will be required to notify public officials 72 hours before releasing the mosquitoes, and conduct tests for at least 10 weeks to ensure that none of the female mosquitoes survive.

Despite criticism from the public, officials decided that the risk of mosquito-borne diseases were evident enough to risk using genetically engineered mosquitoes. While there have not been any documented adverse effects to humans or the environment, many people are still skeptical over the lack of data and information released to the public. Nevertheless, with new technology emerging in genetic engineering, officials have decided that these mosquitoes may be a solution for controlling mosquito-borne illnesses.


Press, A. (2020, August 24). Florida Keys releasing genetically modified mosquitoes to fight illness. Retrieved September 08, 2020, from

The Reality of Malaria [PDF]. (n.d.). New York, New York: UNICEF.

Morrison, N. (2020, May 01). Oxitec’s Friendly™ mosquito technology receives U.S. EPA approval for pilot projects in U.S. Retrieved September 08, 2020, from

Milius, S. (2020, August 22). Genetically modified mosquitoes have been OK’d for a first U.S. test flight. Retrieved September 08, 2020, from

Winter, L. (2020, August 21). 750 Million GM Mosquitoes Will Be Released in the Florida Keys. Retrieved September 08, 2020, from

LaMotte, S. (2020, August 20). 750 million genetically engineered mosquitoes approved for release in Florida Keys. Retrieved September 08, 2020, from

Evans, B.R., Kotsakiozi, P., Costa-da-Silva, A.L. et al. Transgenic Aedes aegypti Mosquitoes Transfer Genes into a Natural Population. Sci Rep9, 13047 (2019).

Press Release. (2019, November 14). TDR | Mosquito sterilization offers new opportunity to control dengue, Zika and chikungunya. Retrieved September 08, 2020, from

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