MUSEUM OF POSTNATURAL HISTORY
disease
Anti-malarial mosquito
This mosquito (Anopheles stephensi) has been genetically altered so that it can not carry the malaria-causing parasite. Developed at the University of California at Irvine in 2009, it is one of many mosquitoes reared in the lab with the intention of release into the wild. It is an early example of an ongoing effort to mitigate human diseases by altering, or eliminating, the animals that carry them.
Researchers have adopted the so-called "replacement" strategy. It involves replacing the target population with mosquitoes carrying a genetic modification that blocks their ability to transmit the pathogen. To achieve this goal, carefully engineered DNA containing a gene resistant to the parasite was injected by hand into thousands of mosquito embryos. The transgenic mosquitoes are then mass-released into the field in the hope that they will mate with the wild population. The mating between a genetically modified individual and a wild individual allows the hereditary transmission of the new anti-malarial genetic trait. Theoretically, this characteristic could eventually spread throughout the entire population.
The "suppression" strategy is more radical. It aims to reduce, or even eliminate, the target population by introducing genetically engineered mosquitoes that are lethal or sterile. In this perspective, the British biotechnology company Oxitec has developed a technique involving the release of transgenic male mosquitoes carrying a lethal gene that kills the offspring.
The company has developed a new transgenic strain of Aedes aegypti, called "OX513A". It was tested in several cities in Brazil between 2013 and 2015. These trials have caused controversy by showing that, in rare cases, hybrid descendants survived, leading to the spread of genes from the mutant strain in wild populations. Since 2021, new trials have been conducted in Florida, USA.
Today, the prospect of using transgenic mosquitoes for the reduction, suppression, or modification of mosquito populations is a reality. Laboratories worldwide are developing different mosquito strains, based on various methods and technologies, some of which are already being tested under natural conditions, on a larger or smaller scale.
Living environment in lab
Photo credit: Richard Pell.
