Leveraging evolutionary forces to improve SIT control for arboviruses

Releases of sterile male mosquitoes are failing to mate with wild females often enough to suppress disease-carrying populations, so researchers plan to evolve better-performing males by intensifying sexual competition in the lab. The problem is practical. Sterile male releases—a technique called the sterile insect technique (SIT)—can reduce Aedes aegypti populations and lower the risk of arboviruses such as dengue, Zika, and chikungunya. But the method works only when released males outnumber wild males by a large margin, a ratio that is expensive and logistically difficult to maintain. The root cause is that lab-reared males are poor competitors in the wild. The researchers’ previous work suggests that sexual selection—the evolutionary pressure to outcompete rivals for mates—normally drives male quality and maintains genetic diversity. Current rearing conditions remove that pressure. The team will evolve replicate populations of *Aedes aegypti* under different intensities of sexual selection, then measure how each regime affects male competitiveness, colony productivity, and predicted population suppression. If stronger sexual selection produces more competitive males, the approach could make SIT far more efficient—requiring fewer released males per wild male to achieve the same suppression. That would lower costs and expand the geographic scale at which the technique can be deployed against mosquito-borne disease.