Self-destructing mosquitoes are maybe possibly my favourite invention of the century. OK, smartphones and Spotify are pretty great, too, but having just spent a couple of weeks in bug-infested New England, I might be a tad biased.
Mosquitos, as we know, are one of the main vectors of infectious disease worldwide, particularly in the tropics. Every year, the little bastards are responsible for 400 million cases of dengue fever and 300 to 600 million cases of malaria, not to mention yellow fever, chikungunya, and many, many more illnesses. Some mosquitoes are worse than others: the leading culprit behind many tropical diseases, for instance, is Aedes aegypti, a critter that thrives in urban areas and is highly resistant to insecticide.
In an experiment that might be construed as evil if we weren’t talking about mosquitoes, the insect control company Oxitec decided to see what happens when Aedes aegypti eggs are injected with a custom gene that hinders development. The gene doesn’t kill the mosquitoes outright, it simply prevents their offspring from reaching sexual maturity.
Once its genetically modified self-destruction bugs had reached adulthood, Oxitec began field trials, releasing them into the wild in dengue-ridden regions of Panama, Brazil, Malaysia, and the Cayman Islands. By unleashing ‘a sufficient number of male mosquitoes’ to outcompete the local bugs (this sounds like a horrifying experiment, if well intentioned), the company was able to suppress wild populations by over 90 per cent. Oxitec is planning additional trials for the Florida Keys later this year, pending FDA approval.
The idea of releasing genetically modified mosquitoes to suppress wild populations isn’t new — in fact, the World Health Organisation has been promoting the strategy for years — but the recent effort represents one of the largest and most successful field trials to date. Still it’s not entirely clear that genetically-modified bugs will become a long-term solution: Genes that have a negative effect on a population tend to get weeded out, quickly, by natural selection. And viruses have a nasty way of jumping from one host to another. It will take several years of field data to be able to say with any confidence that we’ve made a lasting dent.
Still, eliminating nine out of ten wild mosquitoes — without insecticide — is no small feat, and I for one am very interested to see how this effort develops.
Top image via Shutterstock