Genetically modified mosquitoes

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Genetically modified (GM) mosquitoes are mosquitoes that have been artificially implanted with genes not naturally present in the insect. The goal is to control mosquito populations and reduce the spread of mosquito-borne diseases like malaria, dengue, Zika, and chikungunya. GM mosquitoes are engineered to carry a self-limiting gene that prevents female offspring from surviving to adulthood, and a fluorescent marker gene to identify them in the wild.

To create GM mosquitoes, scientists use a process called transgenesis, which involves inserting foreign DNA into the mosquito genome. This is typically done by injecting the DNA into mosquito embryos using a fine needle. The DNA contains the desired genes, such as those that make females infertile or cause offspring to die before reaching adulthood. It also includes a fluorescent marker gene, so the GM mosquitoes can be distinguished from wild ones.

Once the DNA is injected, the embryos are allowed to develop into adult mosquitoes, which are then bred to create a colony of GM mosquitoes. Only the male GM mosquitoes are released into the wild, as they don't bite and cannot spread disease. When released, GM males mate with wild females, passing on these genes and decreasing the population over time. For example, the company Oxitec has released over 1 billion GM Aedes aegyptimosquitoes in Brazil, the Cayman Islands, Panama and the US since 2019, successfully suppressing local populations of this species that spreads dengue, Zika and other diseases.

Terms

• Aedes aegypti: A species of mosquito that is the primary vector for transmitting dengue, Zika, chikungunya, and yellow fever viruses.

• Chikungunya: A viral disease transmitted by Aedes mosquitoes that causes fever and severe joint pain.

• Dengue: A mosquito-borne viral infection that causes flu-like illness and can develop into a potentially lethal complication called severe dengue.

• Fluorescent marker gene: A gene that makes the GM mosquitoes glow under a special light, allowing researchers to identify them in the wild.

• Genetically modified (GM) mosquitoes: Mosquitoes that have been artificially implanted with genes not naturally present in the insect, in order to control populations and reduce disease spread.

• Malaria: A life-threatening disease caused by parasites transmitted to people through the bites of infected female Anopheles mosquitoes.

• Transgenesis: The process of introducing an exogenous gene called a transgene into a living organism so that the organism will exhibit a new property and transmit that property to its offspring.

• Zika: A viral disease transmitted primarily by Aedes mosquitoes that can cause birth defects and neurological complications.

Analogy

GM mosquitoes are like a Trojan horse. Just as the Greeks used a wooden horse to sneak soldiers into Troy, scientists use GM mosquitoes to infiltrate wild mosquito populations and pass on genes that limit their ability to reproduce and spread disease. The GM "soldiers" mate with wild mosquitoes, and their offspring inherit the self-limiting and marker genes, ultimately leading to a population crash. It's an insidious but effective way to target dangerous mosquitoes from within.

Misconception

One common misconception is that GM mosquitoes might bite people and cause some kind of genetic harm. In reality, only the non-biting males are released, and the genetic modifications are designed to be self-limiting, not spread to other organisms. There's also a misconception that wiping out mosquitoes would damage ecosystems. But the targeted species like Aedes aegypti are invasive in many areas and not crucial to the food chain. Eliminating them can actually restore native mosquito populations. For example, in the Florida Keys, using GM mosquitoes to suppress Ae. aegypti is expected to benefit the native salt marsh mosquito and other local species.

History

1. 1902: The mosquito Aedes aegypti is identified as the vector for yellow fever.

2. 1930s-1940s: Scientists begin using radiation to induce sterility in male mosquitoes as a form of population control.

3. 1950s-1960s: DDT and other insecticides are widely used to control mosquitoes, but resistance soon emerges.

4. 1970s-1990s: Research advances in genetics and molecular biology pave the way for genetic engineering of mosquitoes.

5. 2002: Scientists at Imperial College London create the first genetically modified mosquitoes.

6. 2010s: Field trials of GM mosquitoes begin in several countries, including Brazil, the Cayman Islands, and Malaysia.

7. 2020s: GM mosquito programs expand to larger scales, with releases in Florida and Texas. Research also progresses on using gene drives to control malaria vectors in Africa.

How to use it

1. Let's say you live in an area with high rates of dengue fever, spread by Aedes aegypti mosquitoes. Local authorities might release GM Ae. aegypti males to mate with the wild females. Over time, as the self-limiting gene spreads, the Ae. aegyptipopulation would crash, reducing dengue transmission. You could support this effort by allowing access to your property for mosquito monitoring and reporting any concerns to the project team.

2. If you're traveling to a country where GM mosquitoes are being used, it's important to still take normal precautions against mosquito bites, like using repellent and wearing long sleeves and pants, especially at dawn and dusk. The GM mosquitoes won't directly protect you. They're a long-term population control strategy, not an immediate personal defense.

3. As a citizen, you can advocate for the responsible use of GM mosquitoes in your community if you live in an area affected by mosquito-borne diseases. Attend public meetings, write to your representatives, and stay informed about the latest research and regulations. Support efforts to combine GM mosquitoes with other control methods like insecticide-treated bed nets and improved sanitation for maximum impact.

Facts

• The company Oxitec has released over 1 billion GM mosquitoes globally since 2019.

• GM mosquito releases in Brazil reduced the target Aedes aegypti populations by up to 96%.

• The U.S. Environmental Protection Agency has approved the release of GM mosquitoes in Florida and Texas.

• Malaria kills over 400,000 people per year, mostly children under 5 in sub-Saharan Africa.

• Scientists estimate that gene drive techniques could potentially eradicate malaria within 20-25 years.