Abstract

In our screening program for new agrochemicals from Chinese medicinal herbs and wild plants, essential oil of Kadsura heteroclite stems was found to possess strong toxicities against the root-knot nematode, Meloidogyne incognita and the maize weevil, Sitophilus zeamais. The essential oil of K. heteroclita was extracted via hydrodistillation and analyzed by GC-FID and GC-MS. A total of 46 components of the essential oil were identified. The main components of the essential oil were a-eudesmol (17.56%), 4-terpineol (9.74%), δ-cadinene (9.27%), and δ-cadinol (6.32%) followed by δ-4-carene (4.78%) and calarene (4.01%). The essential oil exhibited strong nematicidal activity against M. incognita with an LC₅₀ value of 122.94 μg/ml. The essential oil possessed contact toxicity against S. zeamaisadults with an LD₅₀ value of 25.57 μg/adult and also showed pronounced fumigant toxicity against S. zeamais (LC₅₀ = 14.04 mg/L air). The essential oil of K. heteroclite shows potential to be developed as a possible natural insecticide/nematicide for control of stored product insects/nematodes.

Key words: Kadsura heteroclita, Sitophilus zeamais, Meloidogyne incognita, nematicidal activity, contact toxicity, fumigant, essential oil composition.