Study of induced resistance in wheat, Triticum aestivum L., to English grain aphid, Sitobion avenae (Fabricius) (Hem.: Aphididae) under laboratory conditions

English grain aphid, Sitobion avenae (Fabricius), is an important pest of cereal, particularly wheat. The biological parameters of aphid were determined in a growth chamber at 25±2° C, 60±5% R. H. and 14:10 (L: D) conditionsin a completely randomized design as a split plot experiment. The main factor was wheat cultivars of Sysonz and Shiroodi, and the subplot consisted of five different pre- infestation periods (0, 2, 4, 6 and 8 days). The results indicated significant differences among the treatments in the aspect of net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ), doubling time (DT) and mean generation time (T) of S. avenae. The highest and lowest rm in Saysonz cultivar was observed on control (0.092 d-1) and 6 days pre- infestation period treatment (0.063 d-1), respectively. Also, the highest and lowest rm in Shiroodi cultivar was obtained on control (0.216 d-1) and 6 days pre- infestation period (0.157 d-1), respectively. Therefore, it was concluded that the prior infestation of the wheat plants by this aphid for a 6 days period, can reduce population growth rate of the aphid and so it can be used in the IPM of the aphid.