[Effects of volatiles from different trophic level on foraging behavior of Aphidius avenae]

The responses of female Aphidius avenae to volatiles from undamaged wheat plant, Sitobion avenae and Rhopalosiphum padi, aphids-plant complexes and aphids damaged plant were investigated in wind tunnel and Y-tube olfactometer. The volatiles from undamaged wheat plant, S. avenae and R. padi were much less attractive to A. avenae than those from aphids-plant complexes and aphids-damaged plant. Although the parasitic rate was much lower, the R. padi-plant complexes and R. padi damaged plant were also attractive to A. avenae. Identification of volatiles by GC-MS showed that the main volatiles induced by aphids feeding were 2-camphene, 6-methyl-5-hepten-2-one, 6-methyl-5-hepten-2-ol, Z-3-hexenyl-acetate, and methyl salicylate, among which, 6-methyl-5-hepten-2-one and 6-methyl-5-hepten-2-ol were more attractive to A. avenae, while methyl salicylate was not attractive.