Abstract: 【Aim】 The objective of this research was to determine the low threshold concentration of E-β-farnesene (EβF) in paraffin oil for repelling the wheat aphid, Sitobion avenae, and to provide a reference for field application of EβF. 【Methods】 The effects of different doses of EβF on escaping behavior of the 3rd instar nymphs of S. avenae on wheat seedlings and their behavioral response in Y-tube olfactometer were investigated. Wheat seedlings in a pot were infested with 15 individuals of the 1st instar nymphal aphids. Filter paper strips impregnated with 10 μL of EβF at different concentrations were attached to toothpicks which were placed at the central area of the pot. Filter paper strips were replaced five times every day (9:00, 11:30, 14:00, 16:30 and 19:00) for consecutive five days, and winged and wingless adult aphids were recorded. After two weeks, the population size of aphids was counted. 【Results】 With the increase of EβF dose, the number of escaping aphids in 3 min increased significantly, while the percent of winged adult aphids increased but the population size of aphids decreased significantly after treatment, and the repelling effects increased significantly. EβF at the concentration of 200 ng/μL and ≥600 ng/μL caused significant decrease in the population size of aphids (P<0.05). Choice behavior bioassay with Y-tube olfactometer indicated that the 3rd instar nymphal aphids were significantly repelled by ≥600 ng/μL EβF （P<0.01). The percent of winged adult aphids in treatments with ≥600 ng/μL EβF was significantly higher than that in the control (P<0.01). The aphid population growth was significantly inhibited by ≥400 ng/μL EβF (P<0.01), but there was no statistical difference between treatments with 400 ng/μL and 600 ng/μL EβF. 【Conclusion】 We so proposed 600 ng/μL EβF in paraffin oil as the low threshold concentration of EβF for repelling S. avenae.

Key words: Sitobion avenae, E-β-farnesene, behavioral response, repellent, threshold concentration