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Genetically modified mosquitoes released in US
Read more on - Polity | Economy | Schemes | S&T | Environment
- The story: In May, mosquito eggs placed in the Florida Keys were expected to hatch tens of thousands of genetically modified mosquitoes, a result of the first U.S. release of such insects in the wild. A biotechnology firm called Oxitec delivered the eggs in late April 2021 as part of a federally approved experiment to study the use of genetic engineering, rather than insecticides, to control disease-carrying mosquito populations.
- Why do it: The move targets an invasive species, called Aedes aegypti, that carries Zika, dengue, chikungunya, yellow fever and other potentially deadly diseases, some of which are on the rise in Florida. The experiment relies on a genetic alteration that will be lethal to a large number of future offspring.
- In this case, male mosquitoes have been modified to carry a gene that makes their female progeny dependent on the antibiotic tetracycline, and thus fated to die in the wild. As the mating cycle repeats over generations, female numbers are depleted, and the population is suppressed. The modified insects eventually die off, making this approach self-limiting (so the entire species won't die down).
- Oxitec overcame significant regulatory hurdles before getting the go-ahead from the U.S. Food and Drug Administration in 2016 and then the Environmental Protection Agency in 2020.
- If the current pilot effort is successful, the firm is set to release as many as 20 million more males in the prime of Florida’s mosquito season later in 2021. The results of the experiment could ultimately help address concerns about releasing genetically modified organisms into the wild.
- Current and future methods: The current method of controlling this species is to use insecticides, but they don’t really work well. There is resistance in the field, so new technologies are needed. The firm Oxitec’s technology for releasing genetically modified insects has been tested in other places. Given its prior testing in Brazil, the firm feels this experiment in the US is likely to work and to suppress A. aegypti populations. Hopefully it will directly translate into an epidemiological impact, effectively reducing disease transmission.
- Safety of this genetic technology: The firm says it is extremely safe. The real question here is: What are the existing control mechanisms that are in place? This mosquito has been controlled using many different broad-spectrum insecticides in Florida, including pyrethroids that also kill honeybees, ladybugs, dragonflies and other insects. By comparison, the new technology is only going to target A. aegypti, and will use the mosquito to control the mosquito.
- No out of control scenario: It’s a misconception that this process could get rid of all mosquitoes. There are more than 3,500 different species of mosquitoes on earth. A handful of them transmit pathogens. The firm is not trying to eliminate all mosquitoes. The mosquito species — A. aegypti — is invasive and doesn’t have a purpose in this environment. The first requirement for use of the technology in other areas later, will be success with the current experiment in Florida.
- Possible limitations: The basic question is of scalability. Can it be scaled to eliminate this pest from all of America? Or is it only useful in small communities? Also, species-specific technology is a double-edged sword. On the one hand, you’re only targeting one species. On the other hand, there are often multiple species transmitting a pathogen. For example, in Brazil, two different species that transmit dengue virus — A. aegypti and Aedes albopictus. That’s also the case in Florida. So if science get rid of one of them, the other is still out there.
- Global interest: The firm Oxitec has received approvals to do releases of its modified A. aegypti mosquitoes in the Cayman Islands and Panama. It is doing trials in India — genetically modified mosquitoes are released into cages with wild-type mosquitoes to mate and then compared with cages without the modified insect. With global warming, the habitable range of A. aegypti mosquitoes is expanding. The species now is present in many U.S. states, whereas 10 years ago it wasn’t.
- Summary: There is also a new CRISPR-based technology that can be used to eliminate A. aegypti populations, and it’s also self-limiting. Clearly, genetic engineering is now entering real world applications, and one can only hope that it doesn't run out of control. The fear is real, as the Chaotician in movie Jurassic Park beautifully said, "life always finds a way, and cannot and will not be contained".
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