Sterile male mosquitoes could help in the battle against malaria
A widespread release of such sterile males could have a major impact on transmission rates of the disease, which kills almost 800,000 people a year. The malarial parasite, Plasmodium, is adept in acquiring resistance to new antimalarial drugs. Its main disease-causing carrier in humans - the Anopheles gambiae mosquito, is also quick to adapt to environmentally unfriendly insecticides.
Lead author of the study, Dr Flaminia Catteruccia from the Department of Life Sciences at Imperial College London, said: "In the fight against malaria, many hope that the ability to genetically control the mosquito vector will one day be an key part of our armoury.
For this to work, we need to make sure that the insects continue to mate as normal, unaware that we have interfered with their sexual mechanisms. This study strongly suggests that females cannot tell the difference between a fertile and a spermless mate."Researchers at Imperial College, London produced spermless mosquitoes by genetically modifying the gene for sperm production in the male, rendering them sterile.
One hundred spermless males were produced for the study by injecting mosquito eggs with a protein that prevented the normal development of the testes.
Key to the success of this lab-based research is that female mosquito behaviour does not change after mating with the sterile males. Researchers observed copulating couple's behaviour by isolating each pair under glass tubes.
The fertile females behaved normally after mating, consuming a blood meal and critically did not seek out another sexual partner, laying infertile eggs that could not develop.
The research was published in Proceedings of the National Academy of Sciences (PNAS) today.
The scientists believe that it is also possible that the lab-generated sterile males might have an advantage over their wild and fertile cousins, because sperm production comes at such a heavy metabolic cost.
Co-author Professor Charles Godfray, from the University of Oxford Department of Zoology, said: "This is an exciting time with modern genetics providing a series of new ideas about how to control the major insect vectors of human disease, including the mosquito Anopheles gambiae - perhaps the single most dangerous insect species for mankind. A number of these techniques involve disrupting natural mating patterns and to get these to work a really good understanding of mosquito mating and reproduction is essential."
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