Abstract:  【Aim】 To evaluate the attractiveness of three plant volatile compounds linalool, methyl jasmonate and geraniol to Thrips hawaiiensis and Orius strigicollis, so as to provide a basis for utilizing plant volatile compounds to attract O. strigicollis for controlling T. hawaiiensis in the field. 【Methods】 The attraction rates of linalool, methyl jasmonate and geraniol at the concentrations of 980, 10, 0.1 and 0.001 g/L to T. hawaiiensis adults, and the 5th instar nymphs and adults of O. strigicollis were tested, and the time effect of attraction and attraction rates of 980, 10 and 0.1 g/L geraniol to adults of T. hawaiiensis and O. strigicollis were determined using a Y-type olfactometer. The numbers of T. hawaiiensis and O. strigicollis adults attracted by 10 g/L geraniol were further determined in the field greenhouse condition. 【Results】 The attraction rates of methyl jasmonate at various test concentrations to T. hawaiiensis adults and the 5th instar nymphs of O. strigicollis were not significantly different from those of the control group (paraffin oil). Linalool at the concentration of 980 g/L showed significantly enhanced attraction rate to T. hawaiiensis adults but linalool at various test concentrations exhibited no significant change in the attraction rate to the 5th instar nymphs and adults of O. strigicollis compared with the control group. The attraction rate of pure geraniol (980 g/L) to T. hawaiiensis adults significantly increased, and those of high concentrations (10 and 0.1 g/L) of geraniol to O. strigicollis adults significantly increased but those of 10 and 0.1 g/L geraniol to O. strigicollis nymphs did not change significantly as compared with those in the control group. Geraniol at different concentrations had a significant time effect on the number of T. hawaiiensis and O. strigicollis adults attracted, and the number of adults attracted by 980 and 10 g/L geraniol were significantly higher than those attracted by geraniol at the other concentrations at 2 h after treatment. Regardless of whether the pepper seedlings were damaged by T. hawaiiensis adults or not, those treated with 980 and 10 g/L geraniol had significantly higher attraction rates to adults of O. strigicollis compared with the control (clean water). Treatment group spraying 10 g/L geraniol in the field greenhouses had no significant difference in the number of attracted adults of T. hawaiiensi in 5 h but had significantly increased number of attracted adults of O. strigicollis compared with the control group spraying clear water. 【Conclusion】 Three plant volatile compounds linalool, methyl jasmonate and geraniol have different attraction rates to T. hawaiiensis and O. strigicollis. Geraniol at the concentration of 10 g/L can effectively attract adult O. strigicollis within 5 h but can not significantly attract T. hawaiiensis. These results provide the theoretical basis and technical support for using geraniol to attract O. strigicollis for controlling T. hawaiiensis.

Key words: Thrips hawaiiensis, Orius strigicollis, plant volatiles, attractiveness, recruitment, geraniol