Aedes aegypti.

Responsible for spreading fatal and contagious diseases like the Zika virus, dengue, chikungunya, and yellow fever, these mosquitoes are quite the worldwide threat to public health. Many of the diseases they pass have no cure.

Therefore, quelling the Aedes aegypti population is one of the main priorities of public health agencies. However, most of the numerous attempts to do so fell flat—in fact, Aedes aegypti had developed an immunity to the insecticides currently sprayed. Now, the mosquitoes are endangering people living on the Florida coast and islands. Since they had brought the Zika virus to the state, the Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) decided it was time to make another call towards innovation—a genetic innovation. Oxitec, a biotech firm in the UK, had been permitted to perform a field test of genetically modified Aedes aegypti. This is the very first time the U.S. enabled such an experiment.

These genetically modified mosquitoes, known as OX513A, were field tested in Brazil, Panama, the Cayman Islands, and Malaysia prior to the U.S., and the experiments showed significant success: the population of Aedes aegypti was reduced by 90%. In the field test in Brazil, 95% of the population was depleted in just 13 weeks. On the other hand, Florida’s current anti-mosquito methods, like spraying insecticides, reduced the population by 30-60%, which wasn’t enough.

But the route to success is fairly simple. Male Aedes aegypti are engineered to contain a gene that would produce a fatal protein. In the lab, researchers use an antibiotic called tetracycline to keep the gene inactive until release. Once they are released into the environment, the modified Aedes aegypti males mate with female Aedes aegypti, who are actually the ones that bite. From their offspring, the females die immaturely while the males mature and carry the gene as they repeat the process. Consider the population plunged. 

Last month, researchers went to secluded locations and dropped off boxes containing the OX513A eggs. Each week, 1,000 mosquitoes are expected to fly out of the boxes. By July, 140,000 mosquitoes will be out in the wild. The second phase, predicted to begin around the end of summer, aims to release 20,000,000 OX513A over the course of four months.

Researchers plan to capture the mosquitoes to ensure that the releases are working, determining how far they traveled, how long they lived, and if the immature females were dying. Since OX513A have a fluorescent marker gene, the mosquitoes caught can easily be distinguished as genetically modified or not, as the OX513A glow under certain lights. The data from the captures will be shown to the EPA for further possible OX513A releases in other parts of the U.S.

There are a few concerns and disagreements regarding the OX513A releases. Some local critics are against changing nature, and other scientists are unsure whether their releases could create hybrid DNA in the mosquitoes by mistake. However, if OX513A releases go as expected, the Aedes aegypti will finally see a large decrease in population and halt in spreading diseases from Florida to other areas, save lives, and protect the environment from the insecticides, which would no longer be needed. While OX513A sparks the debate about whether we should mess with nature, perhaps it’s what’s needed to preserve our well-being.

 

written by Saanvi Gutta

edited by Keerthi Selvam and Tryphena Pilli

References:

De La Garza, A. (2021, May 9). Genetically Modified Mosquitoes Have Come to the U.S. Will They Work? TIME. https://time.com/6047051/genetically-modified-mosquitoes/ 

Waltz, E. (2021, May 3). First genetically modified mosquitoes released in the United States. Nature. https://www.nature.com/articles/d41586-021-01186-6 

Liptak, A. (2016, August 5). The FDA just approved genetically modified mosquitoes to fight Zika in Florida. The Verge. https://www.theverge.com/2016/8/5/12387616/zika-florida-genetically-modified-mosquitoes-gene

Townsend, A. (2020, June 6). Controversial genetically modified mosquitoes could cut Zika, West Nile risk. MedicineNet. https://www.medicinenet.com/controversial_genetically_modified_mosquitoes-news.htm

Allen, G. (2016, November 20). Florida Keys Approves Trial Of Genetically Modified Mosquitoes To Fight Zika. NPR. https://www.npr.org/sections/health-shots/2016/11/20/502717253/florida-keys-approves-trial-of-genetically-modified-mosquitoes-to-fight-zika

 

Image Source:

Hands, P. [The catastrophic flooding followed by an extended period of warm weather has led to more algae blooms and swarms of mosquitoes] [Cartoon]. Wisconsin State Journal. https://madison.com/wsj/opinion/cartoon/hands-on-wisconsin-mosquitoes-make-us-long-for-snow/article_ce3b8ec8-364d-55aa-8d31-178b7b901014.html