Genetically-manipulated male mosquitoes could eliminate females

Several years ago, we heard how scientists were looking at eradicating malaria-carrying mosquitoes by making the females infertile. Now they're going a step further, by eliminating the females altogether.

Led by Prof. Andrea Cristani of Imperial College London, an international research team started with a caged population of Anopheles gambiae mosquitoes – this is the mosquito group that's chiefly responsible for the transmission of malaria in sub-Saharan Africa.

The scientists then created a genetically-manipulated version of the males, in which a DNA-cutting enzyme destroyed the X chromosome during the production of sperm. When those males mated with conventional females, the offspring were predominantly male – this is because while just one X and a Y chromosome trigger the development of males, two X's are required for females.

Ordinarily, the X-destroying gene would only be passed on to about 50 percent of the offspring. Utilizing what's known as gene drive technology, however, the researchers were able to boost that figure to almost 100 percent. As a result, over just a few generations, the caged population of mosquitoes became entirely male – it was thus unsustainable, and collapsed as a result.

It is hoped that once more studies have been conducted, the genetically-manipulated males could be released into wild Anopheles gambiae populations, ultimately eliminating them in specific geographical regions. And even before those populations collapsed completely, the malaria problem would already be addressed, as it's only the female mosquitoes that bite.

"This study represents a key milestone in the long-sought objective to bias the progeny of the human malaria mosquito so that only non-biting males are produced," says Cristani. "Having a proven driving sex-distorter opens a new avenue for scientists to develop genetic vector controls of malaria with the aim of eradicating the disease."

A paper on the research was recently published in the journal Nature Biotechnology.

Source: Imperial College London