Exploring the Possibilities of a Novel Approach in Mosquito Management

In a bid to combat the growing threat of mosquito-borne diseases, researchers are turning to innovative solutions, including genetic engineering and the use of Wolbachia-infected mosquitoes.

Recent studies have shown that mosquito populations are evolving around anti-mosquito interventions, posing a challenge to traditional control methods. However, scientists are not deterred. In the United States, a locally transmitted case of malaria, a disease thought to have been eradicated since 2003, was reported last year, underscoring the need for new approaches.

One such approach is the development of gene drives. Researchers, such as those at Target Malaria, are investigating gene drives that target a sex-determination gene called doublesex. The goal is to ensure that the gene gets inherited, potentially leading to a collapse of the population of malaria-carrying mosquitoes like Anopheles gambiae. In 2021, Target Malaria's researchers demonstrated that their gene drive could achieve this in less than a year.

Another promising solution is the World Mosquito Program's (WMP) mosquito control program, which breeds Wolbachia-infected mosquitoes. These mosquitoes are largely incapable of transmitting many pathogens, including dengue, zika, and malaria. The WMP, headed by Scott O'Neill, is currently undertaking field trials in various countries, with the support of organizations like the Centers for Disease Control and Prevention (CDC) and the Pan American Health Organization (PAHO).

The development and distribution of these mosquitoes could potentially be sped up by the use of drones. In Brazil, field studies suggest that Oxitec mosquitoes, another genetically modified variety, can reduce Aedes aegypti numbers by up to 96 percent in less than a year in some neighbourhoods. Oxitec, a biotechnology company, has released over one billion of these mosquitoes in various countries.

Oxitec's engineered male mosquitoes carry a self-destruct gene that prevents female offspring from surviving to maturity. According to Grey Fransden, CEO of Oxitec, continually pumping modified mosquitoes into an area is a maintenance operation to keep populations controlled.

Other researchers are using genetic engineering to target specific genes in mosquitoes. For instance, Omar Akbari is using a gene editing tool called CRISPR-Cas9 to sterilise male mosquitoes by targeting two genes, one involved in male fertility and the other important for female viability.

However, these advancements come amidst concerns about climate change contributing to the spread of mosquito-borne diseases. As temperatures rise and rainfall patterns shift, mosquito populations are expanding, increasing the risk of disease outbreaks.

Lea Paré Toe, a social scientist with the non-profit Target Malaria in Burkina Faso, is working to understand the societal implications of these new technologies. Federica Bernardini, another researcher, is engineering gene drives that tip the scales of heredity, ensuring that a given gene gets inherited, even if only one parent carries it.

In Yogyakarta, Indonesia, a 2021 field trial saw Wolbachia mosquitoes help drive down dengue cases and hospitalizations by 77 and 86 percent, respectively. The World Mosquito Program has released millions of these mosquitoes in field trials in various countries.

As these new technologies continue to evolve, they offer hope in the fight against mosquito-borne diseases. However, it is crucial that these advancements are approached with caution and that their societal and environmental impacts are fully understood.