PT - JOURNAL ARTICLE AU - Yidong Wang AU - Anna Rensink AU - Ute Fricke AU - Megan C. Riddle AU - Carol Trent AU - Louis van de Zande AU - Eveline C. Verhulst TI - Sexually dimorphic traits and male-specific differentiation are actively regulated by Doublesex during specific developmental windows in <em>Nasonia vitripennis</em> AID - 10.1101/2020.04.19.048553 DP - 2020 Jan 01 TA - bioRxiv PG - 2020.04.19.048553 4099 - http://biorxiv.org/content/early/2020/04/20/2020.04.19.048553.short 4100 - http://biorxiv.org/content/early/2020/04/20/2020.04.19.048553.full AB - Sexually dimorphic traits in insects are rapidly evolving due to sexual selection which can ultimately lead to speciation. However, our knowledge of the underlying sex-specific molecular mechanisms is still scarce. Here we show that the highly conserved gene, Doublesex (Dsx), regulates rapidly diverging sexually dimorphic traits and differentiation in the model parasitoid wasp Nasonia vitripennis (Hymenoptera: Pteromalidae). We present here the revised full Dsx gene structure with an alternative exon one and two additional male NvDsx isoforms, which gives important insights into the evolution of the sex-specific oligomerization domains and C-termini. We show the sex-specific NvDsx expression throughout development, and demonstrate that transient NvDsx silencing in different male developmental stages dramatically shifts the morphology of two sexually dimorphic traits from male to female, with the effect being dependent on the timing of silencing. In addition, transient silencing of NvDsx in early male larvae affects male genitalia tissue growth but not morphology. This shows that male NvDsx is actively required to suppress female-specific traits and promote male-specific traits during specific developmental windows. These results also strongly suggests that in N. vitripennis most sex-specific tissues fully differentiate in the embryonic stage and only need NvDsx input for growth afterwards. This provides a first insight into the regulatory activity of Dsx in Hymenoptera and will help us to better understand the evolutionary and molecular mechanisms involved in sex-specific development, which can eventually lead to the development of new synthetic genetics-based tools for biological pest control by parasitoid wasps.Significance Statement In insects, male and female differentiation is regulated by the highly conserved transcription factor Doublesex (Dsx). The role of Dsx in regulating rapidly evolving sexually dimorphic traits has received less attention, especially in wasps and bees. Here, we mainly focused on Dsx regulation of two sexually dimorphic traits and male genitalia morphology in the parasitoid wasp, Nasonia vitripennis. We demonstrate that Dsx actively regulates male-specific tissue growth and morphology during specific developmental windows. These findings will help us to better understand the molecular mechanisms underlying the rapid evolution of sexual differentiation and sexually dimorphic traits in insects, but may also be the starting point for the development of new tools for biological control of pest insects by parasitoid wasps.Competing Interest StatementThe authors have declared no competing interest.