Sexually dimorphic traits and male-specific differentiation are actively regulated by Doublesex during specific developmental windows in Nasonia vitripennis

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, regulates rapidly diverging sexually dimorphic traits in the model parasitoid wasp (Hymenoptera: Pteromalidae). We present here the revised full gene structure with an alternative first exon, and two additional male isoforms, which gives important insights into the evolution of the sex-specific oligomerization domains and C-termini. We show the sex-specific expression throughout development, and demonstrate that transient 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 in early male larvae affects male genitalia tissue growth but not morphology. This indicates that male is actively required to suppress female-specific traits and to promote male-specific traits during specific developmental windows. These results also strongly suggest that in most sex-specific tissues fully differentiate in the embryonic stage and only need the input of for growth afterwards. This provides a first insight into the regulatory activity of in the Hymenoptera and will help to better understand the evolutionary and molecular mechanisms involved in sex-specific development in this parasitoid wasp, which can eventually lead to the development of new synthetic genetics-based tools for biological pest control by parasitoid wasps.