Abstract: How introduced plants associate with native biotic is one of the fundamental questions in evolutionary biology and invasive biology. Extrafloral nectar ( EFN) bearing plants usually use nectar to attract ants while those ants could help plants defense herbivores; establishing a plant-ant-herbivore interactive system . In this study , we conducted artificial ant- exclusion, EFN- exclusion, herbivore exclusion, ant and herbivore exclusion to compare the differences in response to the change of the extrafloral nectar- ant-herbivore interaction system in an native passionflower ( Passiflora siamica) and an newly introduced species ( P. coccinea) . A total of about 24 ant species were recorded consuming the EFN resource . There was no significant difference in the total number of visiting ants while ant species composition was different in the two Passiflora plants (χ2 = 14 .76 , df = 4 , P < 0 . 01) . The most abundant ant species for P. siamica was Dolichoderus thoracicus while for P. coccinea was Paratrechina sp . The herbivorous insects observed were mainly generalists, including snails, katydisds(Pseudophyllidae) or some larvae of butterflies and moths . The amount of nectar per leaf produced from P. siamica is significantly higher than P. coccinea (Willcox, z = - 3 . 87 , P < 0 . 01) . Ant- exclusion in this experiment did not significantly influence the average leaf loss per plant. The treatments for ant-exclusion, herbivore exclusion , and ant + herbivore exclusion all did not significantly influence the EFN production. As a whole, the plant- ant-generalist herbivore in the two Passiflora species did not show a significant difference in the response to the change , while the interactive system with specialist herbivores request further investigation .

Key words: Extrafloral nectar