GC-MS Analysis of Insecticidal Essential Oil of Aerial Parts of Paederia scandens (Lour) Merrill (Rubiaceae)

Purpose: To investigate the chemical composition and insecticidal activity of the essential oil of the aerial parts of Paederia scandens against the maize weevil, Sitophilus zeamais. Methods: Steam distillation of the aerial parts of P. scandens was carried out using Clavenger apparatus in order to obtain the volatile oils. Gas chromatography/mass spectrometric (GC/MS) analyses (HP-5MS column) of the essential oil were performed and its composition determined. Insecticidal activity of the essential oil was measured following topical application and seal-spaced fumigation. Results: The main components of the essential oil were β-pinene (24.77 %), α-pinene (8.22 %), 1, 8- cineol (8.01 %), δ-terpinene (5.32 %), (E)-β-ocimene (5.21 %), linalool (4.92 %) and 4-terpineol (3.63 %). The essential oil exhibited strong fumigant toxicity against adult S. zeamais with LC50 (lethal concentration at 50 %) value of 7.14 mg/L air. P. scandens essential oil also possessed contact toxicity against S. zeamais with LD50 (lethal dosage at 50 %) value of 47.78 μg/adult insect. Conclusion: The study indicates that the essential oil of P. scandens has a potential for development into a natural fumigant for control of insects in stored grains