Deadly diseases like malaria could be combated by modifying the genetic makeup of mosquitoes to create all-male offspring, according to new research, after researchers were able to eliminate populations of malaria mosquitoes in a laboratory with this modification.

Only female mosquitoes pass on diseases like malaria, so altering their reproduction to bias the sex ratio of offspring towards males has been highlighted as a powerful strategy for managing populations in a bid to combat the disease.

The researchers introduced in the Anopheles gambiae mosquito genome a nuclease enzyme designed to target the X chromosome during male germline formation, thereby favouring fertilisation by only sperm carrying the male sex-determining Y chromosome. This means that only males can be generated in the resulting offspring.

The research, co-authored by Dr Roberto Galizi from Keele University’s School of Life Sciences alongside colleagues from Imperial College London, found that using this method it was possible to generate male mosquitoes that, when released at small frequencies in caged populations containing wild-type insects, were able to bias their sex ratio toward males in a few generations and lead to population collapse.

The findings, published in Nature Biotechnology, have highlighted that this strategy could therefore serve as a potent method of controlling populations of malaria-carrying mosquitoes. However, this study was carried out on caged lab mosquitoes and the research team says that further step-by-step assessments will be required before considering releasing the modified insects in the wild.

Dr Galizi said that these findings support the great potential of such methods as a strategy for malaria vector control, adding: “Research progress in the development of novel genetic control approaches presents an enormous opportunity to help to eradicate malaria and other vector borne diseases by targeting the few insect species that can transmit the disease.

“Malaria in particular is a predominantly rural disease afflicting vast regions of Africa and is difficult to eradicate only by using current methods. This study represents a great step towards this goal and offers the advantage of minimising the fraction of human-biting females whilst reducing their overall number.”