Chemical composition and toxicities of the essential oil derived from Kadsura heteroclita stems against Sitophilus zeamais and Meloidogyne incognita

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.