show Abstracthide AbstractThe polyembryonic parasitic wasp lays one ore two eggs in the host egg. After cleavage, the wasp embryo becomes a morula. A morula divides and eventually produces over 2000 embryos. Molecular mechanisms of polyembryogenesis are unclear. In this study, we examined transcriptome changes before and after the onset of polyembryogenesis. Two libraries were constructed: (1) Morula-stage embryos collected by dissecting from the host eggs 20 h post-parasitism. (2) Polyembryos from host eggs 70 h post-parasitism.