Male mosquitoes do not bite and are not able to transmit pathogens to humans. Female mosquitoes, on the other hand, are dangerous. Researchers at Virginia Tech have proven that one gene can turn Aedes aegypti mosquito females into fertile mosquito males. The results of the study are published in the journal Proceedings of the National Academy of Sciences.

Aedes aegypti female mosquitoes need blood to produce eggs, which makes them the main carriers of pathogens that cause Zika virus and dengue in humans.

The presence of the defining male locus (M locus) determines the male sex in Aedes aegypti, and the M locus is inherited only by the male offspring, much like the human Y chromosome.

Scientists inserted Nix, a previously discovered male defining gene at the M Aedes aegypti locus, into the chromosome region that can be inherited by women. By this, the researchers showed that a single Nix gene was enough to turn females into fertile males. This can be crucial for developing future mosquito control methods.

The researchers created and characterized many transgenic mosquito lines that expressed an additional copy of the Nix gene under the control of its own promoter. Maria Sharakhova, associate professor of the Department of Entomology at the College of Agriculture and Natural Sciences, and Anastasia Naumenko, a former researcher and graduate, mapped the chromosome insertion site of an additional copy of Nix.

Another team of scientists found that one Nix transgene, even without the M locus, was enough to turn females into males with sexually dimorphic features characteristic of men and male gene expression.

Nix-mediated sexual transformation has been found to be very pervasive and stable for many generations in the laboratory, which means that these characteristics will be inherited for future generations.

Michelle Anderson, Senior Research Fellow, Pirbright Institute, UK

The Nix gene now has great potential for developing mosquito control strategies to reduce disease vector populations.

Genetic methods that are based on mating to fight mosquitoes target only one specific species. In this case, scientists are targeting Aedes aegypti, a species that entered America several hundred years ago and poses a threat to humans.

However, more research is needed before potentially useful transgenic lines can be obtained for initial laboratory testing. Scientists want to study the mechanism by which the Nix gene activates the male developmental pathway. The team is also interested in learning how it develops in mosquitoes of the same kind.

Researchers also hope that their results will serve as the basis for future studies of homomorphic sex chromosomes that are found in other insects, vertebrates, and plants.