Abstract: Genetic sex determination includes somatic sex determination, sex differentiation of germ cell and dosage compensation. A common cascade (primary signal>master factor>doublesex gene) exists to determine insect somatic sex. Generally, the primary signals (X-chromosome dosage, M factor on Y, maternal imprinting, piRNA, etc.) are very complex, the master factors (sxl and tra/fem) relatively variable, the doublesex gene (dsx) relatively conserved, and the splicing mode (alternative splicing) of important genes very conserved in the genetic hierarchies of somatic sex determination among different insect species. Somatic sex determination mechanisms in many insects are unclear or short of systematic progress, which limits the clarification about molecular mechanisms of dimorphism. Combined with our research on insect sex-determination mechanisms, we summarized the progress and common rules of the primary signals, master factors and doublesex genes in the sex-determination hierarchies of the representative insects of Diptera, Hymenoptera and Lepidoptera, so providing a theoretical basis for a deeper understanding of insect sex-determination mechanism, an exploitation of sterile insect technique (SIT), and an artificial control of insect sex.

Key words: Insect, sex determination, primary signal, master factor, doublesex gene