A team of scientists has found a way to turn disease-spreading female mosquito embryos into males at a genetic level that can lead to powerful population control strategies. Researchers with the Fralin Life Science Institute at Virginia Tech have identified a gene responsible for sex determination in mosquitoes that can transmit yellow fever, dengue and chikungunya viruses.
Only female mosquitoes bite because they need blood for developing eggs, and researchers believe that a higher ratio of males could reduce disease transmission. The scientists identify a genetic switch called Nix in Aedes aegypti mosquitoes that underlies the difference between males and females. These master switches often reside in genomic black holes, which is why none had been found in mosquitoes or other insects before.
Researcher Zhijian Jake Tu said that nix provides them with exciting opportunities to harness mosquito sex in the fight against infectious diseases because maleness is the ultimate disease-refractory trait. The scientists injected Nix into mosquito embryos and found more than two-thirds of the female mosquitoes developed male genitals and testes. When they removed Nix using a genome-editing method known as CRISPR-Cas9, male mosquitoes developed female genitals.
The study provides the foundation for developing mosquito control strategies by converting females into harmless males or selectively eliminating deadly females. Co-first author Brantley Hall said that targeted reduction of Aedes aegypti populations in areas where they are non-native could have little environmental impact, and drastically improve human health.