Mosquitoes are a menace, and the problem is only getting worse. Thanks to climate change, the planet has seen increasingly severe mosquito seasons, and things don’t look like they’ll get better anytime soon.
Mosquitoes breed in moist environments and can carry diseases and viruses, such as malaria, Zika and dengue, which can be fatal to humans. They can also carry many diseases that can be fatal to animals. Currently, the dominant way of controlling mosquitoes is through wide application of insecticide or radiation for sterilization, but this can be harmful to other organisms.
Thanks to CRISPR technology, though, there may be a solution to the mosquito problem. In a recent journal article in “Nature Communications,” scientists from the University of California detailed a new technique to sterilize male mosquitoes and alter female mosquito vision to stop the spread of these diseases using gene-altering technology.
What Is CRISPR?
CRISPR technology is a relatively new advancement that allows scientists to edit genes. Specifically, CRISPR allows scientists to find certain parts of DNA that reside within cells and alter them. It can also be used to toggle genes on and off.
Though gene-editing technology has been around for a long time, CRISPR makes the process much more accessible, as it’s both inexpensive and easy to use. While CRISPR is mostly used in scientific research right now, we may not be far off from using it to cure diseases and change the genes of humans — though many consider human gene editing unethical.
How Can Scientists Change Mosquito Genes?
Scientists have uncovered a new technique they call the “precision-guided sterile insect technique,” or pgSIT. While most CRISPR procedures affect organisms that spread diseases by passing a gene change down generations, this system is more limited. It targets male mosquito genes that are linked to fertility.
As a result of changing these genes, any offspring these mosquitoes have would be infertile. “pgSIT is a new scalable genetic control system that uses a CRISPR-based approach to engineer deployable mosquitoes that can suppress populations,” said Omar Akbari, one of the study’s authors. “Males don’t transmit diseases, so the idea is that, as you release more and more sterile males, you can suppress the population without relying on harmful chemicals and insecticides.”
But it’s the female population that spreads diseases, so pgSIT targets them, as well. According to the study, the CRISPR technology treatment renders female mosquitoes unable to fly or hold their wings up. It also makes them slower and more lethargic in their movements. Combined, these effects lower the chances that these female mosquitoes will mate or successfully find a blood source and attach to it to spread disease.
A separate study in “Current Biology” identified another use case for gene editing using CRISPR: altering mosquito vision. Blood-feeding insects often use multiple senses to seek out humans, but with CRISPR, scientists can mutate female mosquitoes’ vision in a way that eliminates vision-guided target attraction. This has the potential to reduce mosquitoes’ ability to blood seek even further.
What Could This Mean for the Future?
pgSIT and CRISPR technology could promise drastic population control for mosquitoes in a sustainable way. The system is not designed to eliminate mosquitoes completely from everywhere; instead, it was carefully crafted to be self-limiting and not to linger within the environment. That makes it safe for widespread use.
“This platform technology could be used in the field and adapted to many vectors for controlling wild populations to curtail disease in a safe, confinable and reversible manner,” the researchers reported.
The technology could be specifically used in places that are suffering from mosquito-borne diseases and illnesses. According to the release, pgSIT mosquito eggs could be shipped to these locations (or produced locally) and distributed within that specific environment. Once they hatch, the males will mate with females and produce sterile mosquitoes, thereby decreasing the mosquito population in the area or possibly eliminating it altogether. Alternatively, if the situation is dire, the scientists noted that adult pgSIT mosquitoes could be released, which results in faster suppression of the mosquito population.
The researchers also noted that it’s possible for the technology to be used on other insect populations that spread disease. “The study suggests pgSIT may be an efficient technology for mosquito population control and the first example of one suited for real-world release,” the researchers said in the release. “Going forward, pgSIT may provide an efficient, safe, scalable and environmentally friendly alternative next-generation technology for wild population control of mosquitoes, resulting in wide-scale prevention of human disease transmission.”
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