Efficacy of Heterorhabditis bacteriophora Poinar, 1976 (Rhabditida: Heterorhabditidae) species can be changed on targeted insect pests in different climatic zone. In this study, six different H. bacteriophora strains, which isolated in different cities [Antalya (H. b. 6), Canakkale (H. b. 876), Kirklareli (H. b. 17), Izmir (H. b. HIZ) and Adana (H. b. 10)] from Turkey, were hybridized and their virulence were determined on the last instar of Galleria mellonella (Lepidoptera: Pyralidae) at six different dosages. Male and female individuals of having lowest virulence were crossbred with other strain females and males in vitro conditions. Ten different strains were obtained by hybridization and their virulence was compared with their parent and each other on the last instar larvae of G. melonella. The results showed that 70% of hybridized strains were more effective than their parents. The results indicated that male and female individuals have different effect on the virulence of the hybridized strains. The hybridized strains, which were more effective than their parents, were influenced from female with 42.9% and from male with 57.1%.