Data from the first open-field trial of genetically engineered male mosquitoes with the potential to suppress proliferation of wild mosquitoes carrying dengue virus are reported in a paper published online this week in Nature Biotechnology. The findings confirm laboratory-based findings showing that transgenic male mosquitoes can compete effectively with their wild counterparts for female mates and thus provide a promising approach for controlling mosquito-borne infectious diseases like malaria and dengue.

Mass-release of sterile insects has been previously used to suppress insect populations detrimental to agriculture while avoiding widespread use of pesticides. Other pests can be sterilized by irradiation in the lab and then released into a natural population; however, irradiation reduces the ability of male mosquitoes to compete for mates.

To overcome this problem, Luke Alphey and colleagues used a strain of genetically modified Aedes aegypti mosquitoes that die without a dietary substance given to them in the lab, but not found in the wild. The authors released around 20,000 male mosquitoes over a 10 hectare area on Grand Cayman island over a month. They found that the transgenic mosquitoes’ mating success was about half that of wild mosquitoes, suggesting that they would be useful in insect control programs.

Although this small-scale study needs to be repeated in other locations and with additional strains, the results suggest the feasibility of more extensive releases capable of suppressing mosquito populations.