The overall mean frequency of GD sterility (%) in the cross A was 1. 30% from the cross of F1 males with Canton-S females. The mean frequency of M cytotype was 30.01% from the cross of P(π2) males with F1 wild strains. GD sterility frequencies of TP and TY isofemale lines was mostly determined with M' and Q strains. True M strain was low frequency in all populations. P(M) strain was observed with one or two flies in each populations except for 93(TP). The activity of P factor with In(3L)P in isofemale lines mostly was investigated to be M' and Q strains by results of hybrid dysgenesis. True M strain with In(3L)P was only detected two flies in TY(92) populations. The relative frequencies of GD sterility from M' strain were observed from flies with In(3L)P more than flies without.