Major efforts are currently underway to develop alternative, complementary methods to control mosquito-borne diseases, as the long-term sustainability of current approaches is becoming ever more questionable. Mosquito control using the Sterile Insect Technique (or variants thereof) is highly attractive, and a number of SIT programs targeting the invasive Aedes mosquitoes, vectors of dengue zika and other human arboviruses, are currently underway in many parts of the world including the Americas and Asia. The implementation of these promising technologies to target malaria mosquitoes however, is currently prevented by the absence of adequate genetic sexing strains (GSSs). GSSs completely eliminate females in the laboratory from populations of mass-reared male mosquitoes, destined for release. The release of female mosquitoes, even if sterile is not acceptable, as these contribute to pathogen transmission. Early removal of females from mass-reared populations also has economic benefits, by significantly reducing logistical requirements associated with insect rearing. Despite the importance of GSSs for area-wide control of insects, there has been limited progress in recent years in developing novel systems that are fit-for-purpose. A number of approaches are suitable in theory, including to an extent sex-linked morphological markers (e.g. pupal color), sex- linked insecticide resistance or sex-linked conditional embryonic lethality, but none are available at the moment for mosquitoes.
Our group makes use of state-of-the-art genetic engineering technologies and genomics to rationally design conditional mutations in mosquitoes and other insects to be used for genetic sexing. Our work encompasses a number of different strategies based on rational design avoiding the use of large genetic screens, and in some cases even transgenes (foreign DNA sequences).