Abstract:  【Aim】 The objective of this study is to investigate the preference of Anoplophora chinensis to volatiles of Salix ohsidare in different physiological states, and to further explore the reasons for the difference in behavioral choice of A. chinensis between insect-infested and healthy S. ohsidare. 【Methods】 The volatiles of S. ohsidare twigs in the two physiological states (insect-infested and healthy S. ohsidare) were collected, respectively, by using the dynamic headspace adsorption method, and then the collected volatile samples were identified and analyzed by gas chromatography-mass spectrometry (GC-MS). The electrophysiological and behavioral responses of A. chinensis to standard compounds of the main compounds identified from the volatile samples were analyzed by electroantennogram (EAG) and Y-tube olfactometer, respectively, and the trapping efficacies of single volatile compound and the two-component and three-component formulae of volatile compounds on A. chinensis adults were analyzed by large cage behavior experiment and field trapping test. 【Results】 We identified three main compounds from the volatiles of healthy S. ohsidare twigs, including α-pinene, 3-carene and camphor, and five main compounds from the volatiles of insect-infested S. ohsidare, including α-pinene, β-pinene, 3-carene, β-ocimene and camphor. In addition, the amphor content in the volatiles of insect-infested S. ohsidare twigs was significantly higher than that in the volatiles of healthy S. ohsidare twigs, the 3-carene contents in both the volatiles of insect-infested and healthy S. ohsidare twigs were not significantly different, while the α-pinene content in the volatiles of healthy S. ohsidare twigs was significantly higher than that in the volatiles of insect-infested S. ohsidare twigs. The EAG experiment showed that the relative EAG response value of A. chinensis adults to three compounds, α-pinene, 3-carene and β-ocimene, were relatively high, and gradually increased with the increase of the concentrations of these three compounds. The relative EAG response values of A. chinensis adults to β-pinene and camphor exhibited no significant difference, and the concentration changes of these two compounds had no significant effect on the relative EAG response value. The Y-tube olfactometer experiment showed that α-pinene, 3-carene and β-ocimene at the concentration of 1 mg/mL all attracted significantly more male adults of A. chinensis than the control group (paraffin oil), 1 mg/mL β-ocimene also attracted significantly more female adults than the control group, and 3-carene at the concentration of 10 mg/mL attracted significantly more male adults than the control group. The large cage behavior experiment exhibited that the insect-infested formula D of three components (α-pinene∶3-carene∶β-ocimene=42∶30∶103), α-pinene and β-ocimene attracted the largest number of A. chinensis adults, which was significantly higher than the numbers of A. chinensis adults attracted by the healthy formula H of two components (α-pinene∶3-carene=105∶38) and 3-carene. The field trapping test showed that α-pinene and the insect-infested formula D had the best trapping efficacies on A. chinensis adults, with the number of adults trapped significantly higher than those trapped by β-ocimene and the healthy formula H, while 3-carene and the blank control group did not trap any A. chinensis adults. 【Conclusion】 α-Pinene shared in the volatiles of insect-infested and healthy S. ohsidare twigs and β-ocimene specific in insect-infested S. ohsidare twigs are the two important host plant volatile compounds with the attractiveness to A. chinensis adults, while 3-carene inhibits the attractiveness of α-pinene to A. chinensis adults. We speculate that β-ocimene specific in the volatiles of insect-infested S. ohsidare is one of the causes that insect-infested S. ohsidare is more susceptible to the damage of A. chinensis than healthy S. ohsidare.

Key words: Anoplophora chinensis, Salix ohsidare, plant volatiles, GC-MS, EAG, Y-tube olfactometer, large cage behavior experiment, field trapping