AUTOMICTIC PARTHENOGENESIS AND ITS GENETIC CONSEQUENCE IN BACILLUS-ATTICUS-ATTICUS (INSECTA PHASMATODEA)

The meiotic divisions in the eggs of the diploid thelytokous stick insect Bacillus atticus atticus (2n=34 or 33) were examined in Feulgen squashes. The reduction division is normal and results in two interphase nuclei. These nuclei fuse at the onset of prophase II and a diploid meiotic division II follows. One of the resultant nuclei degenerates and the other starts embryogenesis. This automictic type of parthenogenesis explains the clonal maintenance of cytotypes and also the transmission of different levels of heterozygosity. The degree of heterozygosity is determined by the position of the chiasmata and the orientation of the chromosomes at metaphase II. The production of diploid B. atticus/rossius hybrids and its underlying mechanism are discussed.