Using RNAi to improve sex-sorting in mosquitoes for SIT

The sterile insect technique (SIT) is a chemical-free approach to insect control that involves the mass release of sterile male insects into natural populations to reduce the number of offspring in subsequent generations by outcompeting wild males during mating. SIT has been effective against various insect species, but for the mosquito Aedes aegypti, eliminating females from the pool of sterile males is crucial for successful large-scale release programs. Current methods rely on automated sorting to separate larger female pupae from smaller males before sterilization. However, these methods still suffer from high levels of female contamination, which could worsen disease transmission. Notably, female Aedes aegypti pupae are not only larger but also emerge later than males, suggesting that sex-specific genes play a role in larval development. Identifying and targeting these genes using RNA interference (RNAi) technology could potentially alter larval development and be useful for SIT. Through transcriptomic analyses, we identified 114 female-biased genes, of which we selected 33 for RNAi knockdown experiments using gene-targeting double-stranded RNA (dsRNA). The results demonstrated that knocking down 23 of these genes had a significant impact on female larvae development, a subset of which drastically altered pupation times between males and females. These differences could aid sex-sorting efforts for by allowing a higher proportion of male-only pupae to be collected before any females emerge, potentially improving the effectiveness of SIT for mosquito control.