The Early Sex-Specific Expression of the Fruitless Gene in the Asian Tiger Mosquito Aedes albopictus (Skuse) and Its Functional Conservation in Male Courtship

The Asian tiger mosquito, <i>Aedes albopictus</i>, is an invasive species and a vector for several significant human pathogens. Gaining a deeper understanding of its reproductive biology offers valuable insights into its evolutionary success and may inform the development of sustainable strategies to control its spread. This study presents a comprehensive structural and functional characterization of the <i>fruitless</i> gene in <i>Ae. albopictus</i> (<i>Aalfru</i>), a pivotal regulator of sexual behavior in insects. Through in silico analysis combined with molecular and functional genetics approaches, we identified a high degree of conservation in the <i>fru</i> gene structure and its regulation via sex-specific alternative splicing. Differently from <i>Drosophila</i>, <i>Aedes aegypti</i>, and other dipteran <i>fruitless</i> orthologs, <i>Aalfru</i> sex-specific regulation starts in 1-day-old embryos, rather than the late larval stage. Functional analysis using embryonic RNA interference (RNAi) demonstrated that, <i>Ae. albopictus</i> males with transiently disrupted <i>fru</i> expression at the embryonic stage showed significant deficits in adult mating behavior and failed to produce viable progeny. Our findings elucidate the <i>Aalfru</i> gene's molecular organization, developmental regulation, and critical role in courtship behavior, highlighting its importance in male sexual behavior and reproductive success in <i>Ae. albopictus</i>.