Genetic modification trial slashes mosquito numbers

Posted by Emma Woollacott

Scientists have announced that a field trial in which millions of genetically modified mosquitoes were released in the wild led to a dramtic fall in wild mosquito numbers.

The trial, carried out by Oxford firm Oxitec and the Mosquito Research and Control Unit of Grand Cayman (MRCU) aimed to test a method of combating dengue fever.

It's the world’s fastest growing mosquito-borne viral disease, and one for which there is neither medication nor vaccine. According to the World Health Organization, two fifths of the world’s population, some 2.5 billion people, are at risk.

The genetically sterile strain Aedes aegypti can be reared in large numbers by feeding the mosquitoes with a supplement that turns off the sterility gene temporarily.

The team bred three million sterile males - male mosquitoes don't bite or spread diseases - and then released them into the wild. There, they were able to seek out and mate with wild females - without producing offspring.

They found that the number of mosquitoes in the area fell by 80 percent in six months.

"Oxitec considers that this approach could be used in many countries to help control the Aedes aegypti mosquito and hence prevent dengue fever," says Dr Luke Alphey, chief scientific officer and founder of the company.

"We have been working on this for many years to ensure the approach is both effective and safe. This trial represents the first demonstration in the open field, and we are delighted with the results."