Slit/Robo-mediated axon guidance in Tribolium and Drosophila: Divergent genetic programs build insect nervous systems

► The Robo receptor family has expanded by gene duplication in insects. ► Slit and Robos have highly conserved roles in midline repulsion in flies and beetles. ► Insects build similar nervous systems using different numbers of Robos receptors. ► TcRobo2/3 combines lateral positioning functions of DmRobo2 and DmRobo3. ► Flies and beetles employ distinct mechanisms to regulate Robo receptor activity.