Male only Mosquitos

August 8th, 2014

British researchers claim to have figured out a way to eliminate biting mosquitoes. Since female mosquitoes drink blood when they are producing eggs, and male mosquitoes sip nectar, scientists discovered they could accomplish the goal of stopping mosquitoes from biting by eliminating the female offspring. Like humans, the sex of a mosquito is determined by X and Y-chromosomes. Males have one X, which is inherited from the mother, and one Y, which is inherited from the father. Females, on the other hand, inherit one X chromosome from each of their parents, resulting in two X chromosomes. What the scientists do is damage the X chromosome in the father mosquito, so that he passes along viable Y chromosomes to create male offspring, and non-viable X chromosomes to its would-be female offspring. The result is that only the young non-biting male mosquitoes survive, because a female baby will not hatch alive with one damaged X chromosome. The goal is to use their genetically engineered mosquitoes to make populations of the insects decline in over-infested and disease-ridden areas. Researchers report in Nature Communications that since these lab-engineered mosquitoes are fertile, they will virtually breed themselves out of existence after a few generations. The team at Imperial College London had been working for years to create male-only mosquito families, but the method they used to damage the X chromosome ended up killing all the mosquito larvae. Now they have improved their method by splicing a gene into the mosquitoes that slices up the X chromosome when sperm is produced. This eradication of the paternal X chromosome inhibits it from being transmitted to the next generation, resulting in strains that produce 95 percent male offspring. Once the modified mosquitoes are introduced into the population, the males will start to produce mainly sons, and their sons will do the same. It is possible that mosquito populations will eventually revert back to producing female children after a few years, but researchers would only have to re-introduce the genetically engineered mosquitoes again to restart the process. The approach could be used to fight all types of mosquitoes, not only the Anopheles Gambiae mosquitoes that transmit most Malaria, but also Aedes aegypti and other species that transmit Dengue, Chikungunya, West Nile and other deadly viruses. With regard to other types of mosquito-transmitted viruses; other teams of scientists are working to eliminate these diseases as well. For instance, a team of genetic engineers in Brazil is attempting to fight Dengue Fever by introducing a flaw into their code that kills off young mosquitoes before they can mature. Federal authorities are considering allowing this method to be tried out in Key West, Florida, where Dengue is rearing its head. Another team of scientists in Vietnam is experimenting with infecting mosquitoes with bacteria called Wolbachia that kills them while they are young and prevents them from carrying Dengue. Experts claim that wiping out mosquitoes would be unlikely to disrupt the ecosystem of any region because no other animals need them for a food source, and they do not consume any human waste. What they do is spread a variety of diseases, which leads to hundreds of thousands of deaths annually. The World Health Organization says Malaria infects more than 200 million people and it kills close to 500,000 children each year. The parasite that causes the disease can evolve, making it resistant to drugs. Dengue infects as many as 400 million people a year, and along with other mosquito-borne diseases, Malaria, West Nile and Chikungunya, kills approximately 725,000 people a year. Although the research is still in its early days, these new approaches are promising, and could be cheap and effective ways to eliminate Malaria and other diseases from entire regions of the world.