Investigation of Induced Resistance in Wheat to Sitobion avenae (Hemiptera: Aphididae) under Greenhouse Conditions

English grain aphid, Sitobion avenae (Fabricius), is an important worldwide phloem-feeding pest of wheat due to direct sucking damage and transmission of viruses. Here, we tested the effects of six treatments on the fitness traits of S. avenae including: (1) Wheat with a 6-days aphid infestation, (2) Wheat sprayed with Biomin zinc, (3) Wheat seed treated with Bacillus subtilis, and (4 and 5) Combined treatments of Biomin zinc+pre-infestation and B. subtilis+pre-infestation as well as (6) A control treatment. Results revealed that there were significant differences among treatments concerning some allelochemical contents and aphid fitness traits. Treated with B. subtilis+pre-infestation and B. subtilis increased the total contents of phenol in the wheat leaves versus Biomin zinc+pre-infestation (183.63 mg g^-1 FW). The net Reproductive rate (R_0) of S. avenae was significantly reduced by B. subtilis +pre-infestation (1.533 offspring per adult) compared to the control (6.887 offspring per adult). Treated with B. subtilis+pre-infestation (0.022 d^-1) significantly reduced the intrinsic rate of increase (r) of S. avenae compared with the control (0.105 d^-1). The lowest (0.024) and highest (0.058) Nymph Growth Index (NGI) of aphid were found on B. subtilis+ pre- infestation and the control, respectively. Hence, it was concluded that B. subtilis+pre-infestation in wheat plants can induce systemic resistance to S. avenae, which can be used in the IPM of this aphid.