When you think of Genetically Modified Organisms, food probably comes to mind. You might think of labels on packages in grocery stores that read “GMO-free” because there’s sometimes a negative connotation surrounding anything modified by science. Genetically modified mosquitoes, though, are an emerging tool being used to combat the disease.
The “Sudden Death Mosquito” is a male Aedus aegypti mosquito that has been genetically modified in such a way that its offspring will not survive into adulthood. The purpose of this genetic modification is to eliminate the spread of dengue fever, which annually causes 25,000 deaths and 2.3 million infections, transmitted by the female A. aegypti mosquito (1). The genetic modification also decreases the spread of chikungunya and the Zika virus, which have recently been heavily transmitted by mosquitoes in Brazil (2). The first batch of 19,000 sudden death mosquitoes were first genetically modified and released by a company called Oxitec in 2009 (1). Ever since this quiet release, there has been controversy surrounding genetic modification as well as new advancements with Oxitec’s genetic engineering.
Oxitec, an English biotechnology company based in Brazil, takes pride in being the only company that produces sudden death mosquitoes. Its main goal is to develop genetically modified insects to assist in insect control. The company genetically modifies the male A. aegypti mosquito by injecting its egg with the OX513A gene. This is a lethal, self-limiting gene derived from E. Coli and the Herpes simplex virus. It is lethal because it releases a protein, tTAV, which interferes with all cell activity.
When a mosquito is given this gene, workers at Oxitec immediately give it the gene’s antidote, tetracycline (3). This allows the male mosquito to live long enough to be released into an area to mate with female mosquitoes. Since the offspring of these males receive the lethal OX513A gene but are not given an antidote, they die soon after birth. This cycle rapidly decreases the female mosquito population that carries dengue fever and other illnesses by eliminating the mosquitoes’ ability to repopulate.
In 2009 and 2010, over three million GM mosquitoes were released on Grand Cayman Island and eliminated 80% of virus-carrying mosquitoes on the island for three months. When Oxitec tried to release more mosquitoes in Florida in 2012, residents protested, stating environmental harm caused by the mosquitoes (1)
The main advantage of sudden death mosquitoes is that they can eliminate dengue fever, chikungunya, and the Zika virus. Since GM mosquitoes mate with female mosquitoes and the products die, the mosquito population will eventually become extinct in areas where the GM mosquitoes are released due to an inability to reproduce. The illnesses, then, will no longer be transferred to humans (2). Another advantage of genetically modified mosquitoes is a decrease in pesticide use.
Pesticides, which are expensive and harmful to the environment, are heavily used in areas with disease-carrying mosquitoes (1). While there are advantages, there are also disadvantages brought forth by environmentalists, which involve the need for more testing and negative effects that a lack of mosquitoes could have on ecosystems. Some parties believe that birds, frogs, and other species rely too heavily on mosquitoes for their removal to be safe (4). It is also believed that Oxitec has not done enough testing on mosquitoes and that the mosquitoes could adapt to the OX513A gene and mutate into a stronger disease-carrying mosquito that can reproduce (4).
Sudden death mosquitoes help wipe out many mosquito-spread illnesses, but the disadvantages could make the mosquitoes controversial.
(1) Ross, Heather K. “Scientists Genetically Engineer ‘Dead End’ Mosquitoes to Fight Dengue.” Healthline, https://www.healthline.com/health-news/tech-oxitec-mosquitoes-dengue-fever-032213#1
(2) Ellis, Lauren. “How to Make Genetically Modified Mosquitoes.” Aljazeera America, http://america.aljazeera.com/watch/shows/techknow/articles/2016/1/21/how-to-make-genetically-modified-mosquitoes.html
(3) LaMotte, Sandee. “Stopping Zika: The GMO Mosquito that Kills His Own Offspring.” CNN,http://www.cnn.com/2016/03/07/health/zika-florida-gmo-mosquito/index.html
(4) “Pros and Cons of Genetically Modified Mosquitoes.” Mosquito Magnet, n.d., http://www.mosquitomagnet.com/articles/gmo-mosquitoes-pros-cons
(5) Urquhart, Conal. “Can GM Mosquitoes Rid the World of a Major Killer?” The Guardian, https://www.theguardian.com/environment/2012/jul/15/gm-mosquitoes-dengue-fever-feature