9Hassan S A, Guo M F. Selection of effective strains of egg parasites of the genus Trichogramma (Hym. Trichogrammatidae ) to control the European corn bo rer Ostrinia nubilalis Hb. (Lep.,Pyralidae)[J]. Zeitschrift fur Angewand te Entomologie, 1991, 111: 335-341.