[Aim]Ageratina adenophora Sprengel is an important invasive weed in China, and has caused significant damage to the environment, agriculture, forestry and animal husbandry. This study was to investigate contents of anti-herbivore substance in the native and invasive populations of A. adenophora and its response to parasitism by Procecidochares utilis Stone, which will provide a basis for exploring the chemical ecological mechanism of the continuous expansion of A.adenophora.[Method]The populations of A. adenophora from its native ranges in Mexico (2 populations:M1 and M2) and invasive ranges in China (3 populations:C1, C2 and C3) were selected, and the contents of 6 anti-herbivore substances (Tannin:tannic acid, catechin, and ellagic acid; Flavonoid:quercetin, isoquercetin, and kaempferol) in these populations and their changes after infection by P. utilis were investigated.[Result]The values of C/N in invasive populations were lower than those in native populations, with the largest differences recorded in the stems. The contents of tannic and flavonoid substances were also lower in invasive than native populations. Significantly lower tannic acid and catechin contents were found in shoot tips (32.3% and 26.4%, respectively) in invasive than native populations. A. adenophora produced more anti-herbivore substances, especially tannin, after infected by P. utilis. The content of catechin in M1 population before gall rupture was 163.2% higher than that in non-parasitised plants.[Conclusion]A. adenophora in invasive ranges demonstrated an adaptive change in anti-herbivore substances and C/N ratio. Infection by P. utilis can increase the content of anti-herbivore substances in plants, but this was higher in native populations than in invasive ones, indicating that the adaptability of A. adenophora to stress caused by specific natural enemies decreased significantly.