Releasing Genetically Modified Mosquitoes in Djibouti

Last year genetically modified mosquitoes were released in Djibouti. The technology is new and the biology is interesting, but I am most interested in the politics. I am late to this story, since it was reported months ago. They released male Anopheles stephensi mosquitoes which bear a female lethal gene — they mated with females producing only male viable offspring. This intervention is self-limiting as, without viable female males, both normal and genetically modified, will die off.

Since it is self-limiting, this intervention is much less scary than release of mosquitoes with an added gene which spreads due to meiotic drive (from one parent the gene spreads to chromosomes from both parents so it spreads like a virus). This was the topic of an earlier post in which expressed greater frustration that the other technology was not being used. Another existing but not used technology is sex ratio disruption by which modified DNA causes mosquitoes to produce more male than female offspring. Since sex ratio disruption causes the production of more males than wild type, the added DNA spreads, in principle until all males bear it. Again, this is frightening.

The female lethal approach is less powerful and frightening because it is self-limiting. I am very glad that it is being used. I still advocate use of the even more powerful technologies which are available.