A rapidly evolving female-controlled lock-and-key mechanism determines Aedes mosquito mating success

Mosquitoes, the world's deadliest animal, exemplify single-mating systems where females mate only once in their lifetime, making mate choice critically important for reproductive success and mosquito control. Despite this importance, the mechanisms behind mosquito mating and what prevents the female from mating again remain poorly understood. To address this gap, we developed a dual-color fluorescent sperm system in invasive Aedes aegypti mosquitoes and quantified mating patterns, confirming that 86%-96% of females mate only once. Using behavioral tracking of mating pairs, deep learning, and quantitative analysis at increasing resolution, we discovered that females actively control mating initiation through a previously undescribed behavior: genital tip elongation. This female response is triggered by rapidly evolving male genital structures, creating a lock-and-key mechanism that determines mating success. Comparative analysis revealed that Aedes albopictus, separated from Aedes aegypti by ∼35 million years of evolution, employs a similar female-controlled system. Strikingly, we found that Aedes albopictus males bypass female control when attempting cross-species matings with Aedes aegypti females, but not with conspecific females. This "lock-picking" ability, combined with the known sterility induced by cross-species matings, could explain how Aedes albopictus competitively displaces Aedes aegypti populations in overlapping territories. Our findings redefine mosquito reproduction as a female-controlled process and establish a quantitative framework for investigating the molecular and neurobiological mechanisms underlying mating control and species competition in these globally important disease vectors.