Feulgen-negative Nuclear Division in Habrobracon Eggs after Lethal Exposure to X-Rays or Nitrogen Mustard

Abstract

THE females of the parasitic wasp Habrobracon juglandis (Ashmead) when well fed will store eggs in the first meiotic metaphase (metaphase-1) and retain them until the female is placed with the host¹. The unfertilized eggs develop into viable haploid males. When the untreated egg is oviposited, meiosis proceeds and the pronucleus is formed 30 min. after oviposition at 30° C. The nuclei divide synchronously at the rate of approximately one division every 15 min. At the ninth or tenth cleavage stage (2½–3 hr. after oviposition) most of the nuclei migrate to the egg periphery. After two or three more divisions, cell membranes slowly form between the nuclei, and tissue differentiation begins. The embryo hatches about thirty hours after oviposition and feeds on the paralysed host.