Abstract
Based on cytoplasmic incompatibility, Japanese local populations of Laodelphax striatellus are divided into two groups in accordance with their localities : northeastern and southwestern. Crosses between females of northeastern group and males of southwestern one were sterile whereas the reciprocal crosses were fertile. Test crosses of three newly collected populations, Ishigaki, Kagoshima, and a migrant population from the East China Sea showed that all three belonged to the southwestern group in regard to their crossing type. Some eggs, however, deposited by incompatible male and female pairs exceptionally developed to symphs. To examine wehtherthe nymphs were hybrids, crossing experiments were undertaken between red-eyed mutant females of the northeastern group and black-eyed wild type males of the southwestern. The mutant gene of red eye was recessive on an autosome and was inherited by F2 ir BC1 generations through these crosses. It is, therefore, concluded that normal fertilization occurred in some incompatible eggs.
