A field trial in the Cayman Islands has shown that male mosquitoes engineered to produce non-viable offspring can compete with normal males for mates. This is a key step towards controlling populations of the disease-carrying insect.

Mosquito control is the only available strategy for tackling dengue, a viral disease spread mainly by the Aedes aegypti mosquito for which there is no vaccine. Luke Alphey at Oxitec in Oxford, UK, and his colleagues tested males of an engineered strain of A. aegypti, which produce offspring that don't survive into adulthood and also express a fluorescent marker. The researchers released the mosquitoes in a 10-hectare trial area over a four-week period, so that the engineered insects made up about 16% of the adult male population. Of larvae caught in traps, 9.6% were fluorescent, indicating successful mating by the engineered males.

The authors estimate that the release rate would need to be between 1.4- and 12-fold that used in this trial to suppress the natural mosquito population.

Nature Biotechnol. http://dx.doi.org/10.1038/nbt.2019 (2011)