Abstract: 【Aim】 To clarify the effects of Lygus pratensis infestation on the nutrients and protective enzymes of host plants. 【Methods】 The contents of chlorophyll, soluble sugar, amino acids, and protective enzyme activities in the leaves of 10 host plants (six preference hosts with the preference in the descending order as Chenopodium glaucum, Portulaca oleracea, Amaranthus retroflexus, Medicago sativa, Kochia prostrate and Gossypium hirsutum, and four non-preference hosts including Suaeda glauca, Medicago lupulina, Convolvulus arvensis and Lepidium latifolium) infested by L. pratensis were determined, respectively, using biochemical methods. 【Results】 After the host plants were infested by L. pratensis, decreased chlorophyll contents were recorded in leaves of all the tested hosts, with the lowest decrease rate in A. retroflexus (2.6%) and the highest in M. sativa (26.21%). The soluble sugar contents varied a lot after L. pratensis infestation. The soluble sugar content in infested leaves of K. prostrata was significantly declined by 24.05%, while significantly increased by 68.92% in infested leaves of C. glaucum. Except that the free proline content in leaves of A. retroflexus was decreased by 38.87%, those in leaves of all the other host plants were stimulated by L. pratensis infestation. The protein contents in leaves of all the host plants were all decreased after L. pratensis infestation, with the lowest decline by 2.96% in A. reflexus as compared to the control (uninjured plants). The POD activities in leaves of different host plants increased after L. pratensis infestation, with the highest increase rate (74.23%) in P. oleracea. After L. pratensis infestation, the CAT activities in leaves of host plants fluctuated a lot. The CAT activities in infested leaves of C. glaucum, M. sativa and C. arvensis increased by 45.07%, 30.95% and 22.47%, respectively, as compared to the control. However, significantly decreased CAT activities were observed in infested leaves of P. oleracea and M. lupulina. Except that the SOD activities in leaves of A. lividus and M. lupulina infested by L. pratensis decreased, the SOD activities in leaves of all the other host plants were increased but showed no significant difference. 【Conclusion】 After host plants are injured by L. pratensis, the changes in the contents of chlorophyll and free proline in leaves of host plants are well correlated with the preference of L. pratensis to these hosts, while the contents of soluble sugar and protein and the protective enzyme activity have no correlation with the host preference of L. pratensis.

Key words: Lygus pratensis, host plants, host preference, nutrients, protective enzymes