Isozymes electrophoretic variations among hosts and localities for populations of Bemisia tabaci (Genn.) in Egypt (Hemiptera: Alyrodidae)Abstract : Electrophoretic patterns of two isozymes (á naphthyl acetate Esterase and Malate dehydrogenase) were analyzed to determine variations among populations of Bemisia tabaci (Genn.) collected from nine different host plants at Qalyubiya Governorate and randomly from six Governorates in Egypt. The two analyzed isozymes successively showed polymorphic variations among the studied populations. Phylogenetic relationships among the studied populations were established according to the patterns of these two isozymes. Results concluded that B. tabaci species may be has different genotypes according to different localities and hosts in Egypt.