[D]espite decades of effort, vaccines have, for many [diseases like malaria and dengue], proved tricky to develop.
Better, then, to stop those infections happening in the first place, by exterminating—or at least suppressing—the mosquitoes that carry the diseases. In a paper just published in the Proceedings of the National Academy of Sciences, a team of researchers led by Craig Montell, of the University of California, Santa Barbara, describe how crispr-cas9, a new and powerful genetic-engineering process, could help to do just that.
Dr Montell and his colleagues used crispr to boost an existing control method called the sterile insect technique (sit). This involves releasing lots of sterilised males into the wild. Females that mate with these males produce no offspring.
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Although the details are not fully understood, says Dr Montell, once female mosquitoes have mated a few times, they become less receptive to doing so again… Sure enough, a series of experiments conducted in cages suggested that releasing between five and six genetically modified males for each wild male was enough to cut the number of reproducing females by half. Upping that ratio to 15:1 dropped it by 80%.
