Effect of Three Wheat Varieties on Life Tables Data of Shizaphis graminum (Rond.) and the Predator, Hippodamia variegata Goeze

Life tables data of Shizaphis graminum and Hippodamia variegata on three wheat varieties, Debeira, El nilein and Baladi were studied under laboratory condition. The results show that the net rate of reproduction (R0) was 17.25, 14.05 and 12.87 in Debeira, El nilein and Baladi respectively. The highest innate capacity for numerical increase (rm) was noticed in Debeira variety (0.20) and the lowest one was reported in Baladi and El nilein variety (0.18). The doubling time (DT) was 3.40 days in Debeira, 3.82 days in El nilein and 3.88 days in Baladi. The weighted generation time (T) was 14.01 in Debeira, 14.62 in El nilein and 14.38 in Baladi variety. The life tables data of H. variegata raized on S. graminum in three wheat varieties illustrated that the figures for net rates of reproduction (R0) were 82.48, 82.79 and 81.42 and those of the intrinsic rate of increase were 0.18, 0.19 and 0.18 for the beetles fed on S. graminum raized on Debeira, El nilein and Baladi varieties respectively. The weighted generation time (T) was slightly higher in Debeira (24.45) than the other two varieties. The lowest doubling time DT (3.63 and 3.75) were reported from beetles fed on S. graminum reared on El nilein and Baladi varieties respectively. The results indicated that the buildup of S. graminum population was low in Baladi and El nilein variety.