Mosquitoes are famously attributed for their ability to spread germs. Eager to bite both humans and animals, this action can begin a deadly cascade of disease transmission. However, with the aid of a self-limiting gene, the mosquito species in the United States is undergoing the process of becoming genetically modified to prevent potential disease outbreaks in regions encompassing vulnerable human populations.
According to the Centers for Disease Control and Prevention (CDC), mosquitoes can be grouped into one of two categories: vectors or nuisances. A vector, described as “an animal, insect, or tick that spreads pathogens,” can make a person or an animal sick through one bite. In comparison, a nuisance mosquito can bite but will not spread pathogens during that instance.
With such classifications, invasive mosquito species like Aedes aegypti are being further studied by biologists to understand where and how they are spreading viral diseases. States like California and Florida are becoming primary hotspots for Ae. aegypti colonization because it is a species that flourishes in warm climates. Along with this, the climate change crisis offers no consolation as temperatures continue to rise.
In efforts to prevent future outbreaks of viral diseases that this invasive species can spread, the United States Environmental Protection Agency passed an experimental use permit for the release of over 2.4 million genetically modified Ae. aegypti mosquitoes in California and Florida. Beginning on March 7 of this year, both states will release the first batch of about 1.2 million mosquitoes up until April 30, 2023. For another full year, the release of a second batch with the same amount of insects will begin on April 30, 2023. This second round is expected to last until April 30, 2024.
As the leading force of this project, Oxitec, a biotechnology company described as a “leading developer of biological solutions to control pests that transmit disease, destroy crops and harm livestock,” aims to decrease Ae. aegypti populations in the wild with the exposure of the genetically modified mosquitoes mass-produced by their laboratories.
The process of producing genetically modified insects is driven by the insertion of a self-limiting gene into male mosquitoes. This modified gene prevents female mosquito offspring from living long enough to become adults.
The genetically modified female mosquitoes first lay eggs in the laboratory, where these eggs carry both the self-limiting gene and a fluorescent marker gene that allows researchers to identify them in the wild. Once ready, the eggs are released into a particular environment, where they are expected to hatch and develop normally into adulthood. As adults, the male mosquitoes continue their lives by mating with wild Ae. aegypti females, which pass the self-limiting gene on to their offspring. The female offspring that are produced will die before they are able to become adults, which should repress Ae. aegypti populations.
At UCI, microbiology and molecular genetics professors like Anthony James are on board with such experiments that aim to prevent future disease outbreaks. As a researcher who studies the Ae. aegypti species, James’ own research focuses on developing “novel, genetics-based control methods” that will allow for the blocking of transmission of human pathogens by host mosquitoes.
Through such biological control suggested by James, the use of genetically modified Ae. aegypti mosquitoes can provide positive results in the scientific community.
Since the modified mosquitoes are aimed to target the invasive Ae. aegypti species, native species in the wild will not be harmed. The biological food chain in the wild will be maintained as animals like birds continue to use the native mosquito species as a source of food.
The risks involved with genetically modifying mosquitoes are low because the modified self-limiting gene in female offspring will not be passed to human beings. Although female mosquitoes are the gender of the insect that bites, they do not possess the ability to transmit this gene, which many may be concerned about.
To read more about the Oxitec project and receive updates on the work being done, visit the biotechnology company’s official website.
Korintia Espinoza is a STEM Staff Writer. She can be reached at firstname.lastname@example.org.