Mosquito-borne diseases such as dengue fever and malaria are major threats to human health in tropical zones of the world.Furthermore, changing climate and human activities including migration, land use and urbanization, are now putting at risk people living in more temperate zones.In total, more than half of the global human population is at risk for one of these infections.The lack of effective vaccines and waning efficacy of prophylactic and therapeutic drugs (neither of which exist for dengue fever) and other measures make urgent the development of novel approaches for controlling the diseases.We are developing genetic tools that could contribute to diminishing the ravages of these diseases.