Allelopathic potential and antifeeding activity of Crassocephalum crepidioides against native plants and Spodoptera litura.
Crassocephalum crepidioides is a new invasive plant in China. Bioassays were conducted with aqueous leachates of its fresh leaves to evaluate its suppressive activity against seedling growth of Amaranthus retroflexus, Echinochloa crusgalli and Digitaria sanguinalis. Aqueous leachates from fresh leaves at 0.25 gmL-1 and the soil irrigated with aqueous extracts of C. crepidioides litters 0.025 gmL-1 significantly inhibited the seedling growth of all three tested weed plants (Amaranthus retroflexus L., Echinochloa crusgalli (L.) Beauv. and Digitaria sanguinalis (L.) Scop). The essential oils were analysed by GC-MS. The dominant constituents of the essential oils were-myrcene (27.4%), -pinene (26.2%), germacrene D (5.81%), 1, 6, 10-pentadecatriene (5.54%) and -caryophyllene (4.68%). In laboratory the antifeeding activity of C. crepidioides leaf extract and essential oils were evaluated against the third-instar larvae of Spodoptera litura. The leaf extract and essential oils of C. crepidioides at 4-concentrations (1.25, 2.5, 5, 10% and 0.625, 1.25, 2.5 and 5%, respectively) significantly reduced the leaf damage done by S. litura. The feeding deterrence during 48 h measured after treatment with leaf extract and essential oils at these concentrations ranged from 7.96 to 60.52% and 13.83 to 65.47%, respectively. Both laboratory and pot culture experiments showed the possibility of using allelopathic potential and insecticidal activity of this plant for sustainable pest management.