EVALUATION OF RELEASE OF Diaeretiella rapae (M´ INTOSH) FOR CONTROLLING THE CRUCIFEROUS APHID, Brevicoryne brassicae L. ON CAULIFLOWER PLANTS AT SHARKIA GOVERNORATE, EGYPT.

Rate of parasitism bythe aphid parasitoid, Diaeretiella rapae (M´Intosh)on the cauliflower aphid, Brevicoryne brassicae L. as well the hyperparasitism on D. rapae were recorded, at Kafer Sakr districtSharkia Governorate during the two successive seasons 2010-11 and 2011-12. Total means of parasitism rates of D. rapae were 23.58 and 28.06 % during the two successive seasons, respectively. The parasitoid, D. rapae was parasitized by two hyperparasitism species Pachyneuron sp. and Alloxysta sp .The seasonal means of hyperparasitism percentage were 28.42 and 29.67% during period of study, respectively. The parasitoid density, in relation to that of host density, had influenced on percentage of parasitism. The highest percentage reached was 87.75% at 15 D. rapae female parasitoids per cage and the minimum was 46.1% at three female adult per cage. On the other hand, the average parasitism ratios in green houses were 73.94, 60.74, 54.29 and 39.98 at the parasitoid host ratios 1:4, 1:8, 1:12 and 1:16 respectively. Meanwhile the average parasitism ratios in the field were 58.39, 50.01 and 32.49% at the parasitoid host ratio 1:8, 1:12 and in control during the period of release. The result revealed that the best control of B. brassicae population under green houses conditions was achieved using by the power predator prey ratio (1:4 and 1:8) after 28 days from releasing D. rapae. Finally the parasitoid D. rapae can be used as biological control agents B. brassicae in cauliflower plantation under green houses and under field conditions at the parasitoid host ratios of 1:8 and 1:12.