Influence of Aphis gossypii feeding on defense strategy of native and introduced populations of Ageratina adenophora

Abstract

The crofton weed, Ageratina adenophora, is one of the most invasive alien species in China. To investigate and clarify the defense strategy of A. adenophora under the feeding stress of polyphagous natural enemies, native and introduced A. adenophora populations were fed by different densities of Aphis gossypii (15, 30, 45, and 60 aphids/plant) for different feeding times (0, 24, 48, 72, and 96 h), and variation of nutrients contents, secondary metabolites contents, and antioxidant enzymes activities were determined in both populations. The contents of soluble protein, soluble sugar, and flavonoid, and the activities of peroxidase and superoxide dismutase increased significantly, while the content of tannic acid decreased significantly with the increase of aphid density and feeding time. The trends of such variation in both native and invasive populations were similar. However, the contents of soluble protein, soluble sugar, and flavonoid, and the activities of peroxidase and superoxide dismutase in introduced population were significantly higher (1.92, 1.13, 1.22, 1.16, and 1.61 times, respectively) than those in native population, while the contents of tannic acid in introduced population were significantly lower (89.28%) than those of in native population. In general, introduced A. adenophora population was more sensitive and exhibited stronger resistance to A. gossypii feeding than native population, which might contribute to the defense strategies of A. adenophora with regard to its successful establishment and expansion in invaded area.