Detecting the population dynamics of an autosomal sex ratio distorter transgene in malariavector mosquitoes

The development of genetically modified (GM) mosquitoes and their subsequent field release offers innovative and cost‐effective approaches to reduce mosquito‐borne diseases, such as malaria. A sex‐distorting autosomal transgene has been developed recently in G3 mosquitoes, a laboratory strain of the malaria vector Anopheles gambiae s.l. The transgene expresses an endonuclease called I‐PpoI during spermatogenesis, which selectively cleaves the X chromosome to result in ~95% male progeny. Following the World Health Organization guidance framework for the testing of GM mosquitoes, we assessed the dynamics of this transgene in large cages using a joint experimental modelling approach. We performed a 4‐month experiment in large, indoor cages to study the population genetics of the transgene. The cages were set up to mimic a simple tropical environment with a diurnal light‐cycle, constant temperature and constant humidity. We allowed the generations to overlap to engender a stable age structure in the populations. We constructed a model to mimic the experiments, and used the experimental data to infer the key model parameters. We identified two fitness costs associated with the transgene. First, transgenic adult males have reduced fertility and, second, their female progeny have reduced pupal survival rates. Our results demonstrate that the transgene is likely to disappear in