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Mosquitoes' 'Genetic Achilles Heel'

If you want to put an end to malaria in the regions where it wreaks wretched havoc on populations — malaria kills 1 million people annually — one method would be to simply get rid of the mosquitoes that feast on human blood and leave their hosts with a plasmodium as a parting gift.

If only that were so easy. Many methods have been tried to banish Anopheles mosquitoes from a region, including strafing with pesticides and draining swamps and ponds. But what if we could just wipe out all the females that lay the eggs in the first place?

Enter a team of genetic engineers with some slime mold.

A group based at Imperial College London has worked up a method it says leads females to have almost entirely male offspring, which after a few generations leads to a male-laden and very boring swamp party for Anopheles, and a dying population, the Guardian reports.

"You have a short-term benefit because males don't bite humans [and transmit malaria]," says co-author Andrea Crisanti. "But in the long term you will eventually eradicate or substantially reduce mosquitoes."

The team injected mosquitoes with a slime mold gene called I-PpoI that attaches to the X chromosome in males during the sperm-making process and cleaves ribosomal gene sequences on the chromosome.

This chromosomal hacking caused the females to have offspring that were more than 95 percent male. When these modified mosquitoes then mated with their wild counterparts, they passed on the gene and led to another generation that would create 95 percent male offspring.

"Under field conditions the accumulation of X chromosome damage would significantly contribute to the demise of target populations," the scientists say in the paper in Nature Communications.

The innovation, which Crisanti calls "a quantum leap" compared to what has been done before in this area, is based on an old idea, co-author Nikolai Windbichler says. He says the initial concept for distorting the sex of a pest population was suggested by evolutionary biologist Bill Hamilton, but that there previously was no way to make it work.

"There are selfish chromosomes around but they're too complicated, so we created something like this from scratch, he says. "We found mosquitoes have a genetic Achilles heel."