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Genetically Modified Mosquitoes: Are They Even Safe?


Genetically modified mosquitoes - Dr. Axe

Did you know that genetically modified mosquitoes now exist? It’s true! To date, these scientifically engineered insects have already been released in several areas around the world. Their creation and release have been met with many questions, including is it just a coincidence that GM mosquitoes started flying around in Brazil just before a number of Zinka-linked birth defect cases came about? (1)

Most recently, the Cayman Islands approved a two-stage, island-wide release of these GM mosquitoes for early 2018. (2) As you may have already guessed, just like genetically modified food, genetically modified insects are also a highly questionable human creation.

Scientists are literally manipulating mosquitoes for the purpose of  reducing diseases caused by mosquitoes, but are these genetically modified insects truly the best way to reduce the occurrence of dengue fever and the Zika virus  or will they just end up causing more harm than good? Let’s take a good look at genetically modified mosquitoes pros and cons.

What Are GM Mosquitoes?

Genetically modified mosquitoes are being created and released in an effort to reduce mosquito diseases such as Zika. The genetic modification only targets male mosquitoes. Since only female mosquitoes bite, the idea is that these genetically modified male mosquitoes will help reduce the population of possibly disease-carrying mosquitoes.

Oxitec is the British company behind this human attempt at mosquito control. So exactly how are GM mosquitoes made?

Scientists create genetically modified mosquitoes by inserting what is called a self-limiting gene into their DNA sequence. This gene doesn’t allow the mosquitoes to survive into adulthood; it also causes more than 95 percent their offspring to die before becoming vectors of disease. The genetically modified mosquitoes also contain heritable, fluorescent proteins that provide a marker for scientists to tell them apart from native mosquitoes.

So wait, if the self-limiting gene is deadly, how are genetically modified mosquitoes being produced in labs right now? Here’s the trick. Scientists intervene by giving the insects an antidote that turns off the self-destructive gene. That antidote? The antibiotic tetracycline. This is the same drug commonly used in humans to treat severe acne, other skin issues, urinary tract infections, chlamydia and gonorrhea symptoms.  (There are also a number of concerning tetracycline side effects.) It’s also a go-to drug used on farm animals.

When GE mosquitoes receive tetracycline in the lab, they are able to survive and reproduce in the rearing facility. However, when the genetically modified male mosquitoes are released into the wild and mate with normal female mosquitoes, their offspring will die because they “can’t access the antibiotic in the quantities needed to survive,” according to Oxitec. (3)

Oxitec does not say that the mosquitoes cannot access the antibiotic, but rather that they can’t get it “in the quantities needed to survive.” Does this mean the tetracycline antidote may be available to mosquitoes on some level out in the real world? For example, drugs in the tetracycline group are commonly used to treat farm animals. These meds are often found in farm animal feed, too. In fact, studies show tetracycline is sometimes present in the tissue of various livestock animals raised for human consumption. (4) Could this provide the antibiotic-laced blood meal these GE mosquitoes need to survive?

Why Are They Being Made and Released?

Creators of these GM insects and proponents of their release believe that they will decrease mosquito populations. Since mosquitoes can carry diseases, the hope is that less people will be be stricken with mosquito-derived illnesses. More specifically, these genetically modified versions of mosquitoes can lower the occurrence of illnesses caused by Aedes aegypti mosquitoes.

According to the CDC, Aedes aegypti mosquitoes are the main kind of mosquito that spreads viruses such as Zika, dengue, chikungunya and others. The other Aedes mosquito, Aedes albopictus, can be found in cooler climates than the Aedes aegypti; they are less likely to spread viruses. 

In the United States, Aedes aegypti are common in Hawaii, Florida and along the Gulf Coast, but they have also been spotted as far north as Washington, DC, when temperatures are especially hot. (5)

According to Oxitec, the genetically modified mosquitoes Brazil release resulted in an 82 percent decrease in the mosquito population over eight months. (6) Other proponents of GE mosquitoes say releasing these altered insects into the wild could reduce the need for using toxic insecticides to kill mosquitoes. This is especially noteworthy because mosquitoes are becoming resistant to certain insecticides. (7)

While pesticides may be harmful and not the answer, there are still many questions swirling around the use of genetically modified mosquitoes.

Possible Harms of GM Mosquitoes and Why They Should Be Banned

So why would anyone be against these mosquitoes? What are the downsides? Some people are even wondering, did genetically modified mosquitoes cause Zika?

Genetic modification is clearly a growing science. The possible human health dangers of GMO foods are not even entirely clear yet, but based on animal research, it certainly seems as though GMO foods pose major health risks. It’s a somewhattr similar case for genetically modified mosquitoes. Why? Because there are a lot of questions that can’t be answered with 100 percent certainty. For example, will killing off all of these mosquitoes somehow damage the food chain? What if genetically modified female mosquitoes (females bite) manage to make it into the wild and survive?

In the spring of 2017, mosquitoes manually infected with naturally occuring Wolbachia bacteria were released into the Florida Keys. Mosquitoes with Wolbachia are less able to transmit viruses to humans. Some opponents of the genetic modification of mosquitoes believe that Wolbachia is a better alternative. However, the FDA has now approved genetically modified mosquitoes to be released there too, but this plan is being met with a lot of strong reaction. (8) Many local residents are so concerned about the possible negative effects of these genetically modified creatures that they voted against the release. (9)

The creators of GM mosquitoes use gene-insertion techniques, but many experts find gene-insertion techniques quite troubling. According to experts, these techniques are “fraught with unpredictable mutations and altered gene expressions.” Another valid concern? Oxitec and other creators of GMOs are messing around with the natural gene pool without fully investigating any possible unintended consequences of this human intervention into nature. For example, the fact that DNA changes caused by genetic modification can lead to the development of new toxins, allergens or carcinogens. (10)

One example that warrants concern over genetic modification is a study about cystic fibrosis and gene therapy. This study, published in the journal Molecular Medicine, demonstrated how gene insertion can cause significant and broad DNA changes. (11) This kind of research is a perfect example of the unpredictability of altering the genetic makeup of a living thing, such as a mosquito.

Dr. Helen Wallace, the director of GeneWatch, has multiple issues with the findings of Oxitec’s mosquito trials so far. One of her major concerns is the occurrence of tetracycline (the antibiotic that the young mosquitoes need to survive) in livestock and meat. Oxitec says it’s an unlikely problem, but there is concern over what would happen if a female mosquito that is the daughter of a genetically modified mosquito bites meat or a live animal that contains tetracycline. She would be getting the antidote to the gene that is supposed to kill her. If she doesn’t die and bites someone, then what?

Wallace says: “It’s a very experimental approach which has not yet been successful and may cause more harm than good. They are pushing ahead to commercialize their approach so they can start paying back their investors. I would be happier if there were more experiments in controlled areas, caged areas and labs, before general release in the populated areas. For example, in an area where dengue fever is endemic, there’s a possible danger to the public.”

Wallace thinks that effective mosquito control approaches already exists that work just as well as GM insects. Plus, there are “other innovations on the horizon which could be even more successful.” (12)

The Center for Food Safety also raises issues over disrupting the food chain. Drastically altering the mosquito population could “deprive birds, bats and fish that feed on mosquitos of a major food source.” (13)

Releasing GE mosquitoes into the wild without proper safety testing seems to be short-sighted, especially when considering its potential impacts on the economy, our food supply and biological balance.

Let’s take bats, for example. This is one species that could be most directly impacted by tampering with mosquitoes in an unprecedented way. Taking away mosquitoes could cause already dwindling bat populations to plummet, which inevitably will impact humans (and potentially food prices) in a negative way.

A large economic study found bats’ pest-controlling contribution to agriculture equals up to $53 billion a year. Aside from that, they are also pollinators vital for crop production (14)

By releasing GE mosquitoes into the wild, a corporation is subjecting us (and nature) to an unprecedented experiment. Instead of going to this extreme, why not try a different approach first, like taking better supporting bat populations.

A review study published in the Journal of Environmental Immunology and Toxicology targets neonicotinoid insecticides as a leading cause of mass die-offs impacting bees, bats, songbirds and amphibians. This class of nerve agent-like chemicals is widely used in non-organic farming, and scientists believe some neonicotinoids actually make naturally occurring pathogens more potent. (15)

In my opinion, shouldn’t we clean up the farming system to support better human and bat health first? Remember, more bats equal fewer mosquitoes.

What To Do In Case of GM Mosquitoes

Pest-control experiments have shown time and again the “folly of human intervention into complex ecosystems.” (16) If you live in an area where the release of genetically modified insects is going to occur, you can follow the example of people in the Florida Keys and try to have the release location changed. It’s extreme, but if you feel really concerned then you can always consider moving to an area where mosquito-born illness is highly unlikely and therefore would not be a likely testing zone for genetically modified mosquitoes.

The Cayman Islands region is known for tourism, but if you’re concerned about the possible negative effects of GM insects, then you can always take your vacation in an area of the world that has yet to release genetically modified mosquitoes.

If you live in an area that has genetically modified mosquitoes, then you can do what you can to protect yourself from mosquito bites (see the next section), which is just a good idea in general, since nobody enjoys an itchy, inflamed bite, even if it doesn’t cause illness.

How To Get Rid of Mosquitoes and Avoid Bug Bites

Conventional bug sprays can contain questionable ingredients like DEET. If you’re looking for an all-natural way to keep mosquitoes and other bugs away, I highly recommend making and using this Homemade Bug Spray Recipe.

Dress for mosquitoes. If mosquitoes are particularly bad where you live or you find that they are often attracted to you, use bug spray and protective clothing like long sleeves and pants.

Screen outdoor areas in. It’s also a good idea to stay inside of screened in areas when you can. This way, you can enjoy the fresh air with a much lower likelihood of getting bitten.

Low-tech trick: Turn on a fan. It seems too simple to work, but even the American Mosquito Control Association backs the use of fans to deter mosquito bites. Since mosquitoes are not great fliers, putting a fan on your deck can help keep them at bay. Aside from the wind resistance, it also disperses the natural human attractants that draw female mosquitoes in to bite us. (17)

Ban standing water. Make removing standing water a part of your landscaping routine. Stagnant water is a mosquito’s favorite place for laying their eggs so emptying out anything containing stagnant water around your home is also very important. If you have a small man-made pond or bird bath typically infested with mosquito larvae, you can use mosquito dunks. The bacteria in the dunks will prevent mosquito breeding without hurting birds.

If you do get bit by a mosquito then you’ll want to check out my Top 5 Home Remedies for Mosquito Bites.


Mosquito bites can lead to serious health concerns such as the Zika virus, dengue fever and yellow fever.

Contact your doctor right away if you get a mosquito bite(s) and exhibit any of the following serious symptoms, especially if you have recently been anywhere reporting outbreaks of mosquito-borne illness: (18)

  • Fever
  • Headache
  • Body aches
  • Signs of infection

Final Thoughts

  • Genetically modified mosquitoes are not the first and they certainly won’t be the last human attempt to control nature. I’m really hoping that the Cayman Island release doesn’t happen because it could likely become a  springboard for massive GM insect releases all over the world, including in the United States. If the release does occur as scheduled, I would advise avoiding travel to the Cayman Islands and any other areas that release genetically modified mosquitoes, if you can.
  • In general, it’s wise to do all you can to naturally protect yourself from mosquito bites.
  • Genetically modified mosquitoes just don’t seem like the best answer to mosquito-borne illnesses, especially when there is so much that we don’t know yet.
  • I personally choose to be on the safe side and avoid all genetically modified creations.
  • The Cayman Islands and any other area of the world that chooses to allow the release of genetically modified insects are taking a gamble. I think it’s important to do what we can to reduce the occurrence of mosquito-borne illnesses, but I believe we should also do that in a way that is best for our long-term human and environmental health, as well.

Read Next: Are You at Risk for This Kissing Bug Disease?


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