Gas Chromatography-Mass Spectrometric Analysis and Insecticidal Activity of Essential Oil of Aerial Parts of <i>Mallotus apelta</i> (Lour.) Muell.-Arg. (Euphorbiaceae)

Purpose: To investigate the chemical composition and insecticidal activity of the essential oil of the aerial parts of Mallotus apelta against maize weevils, Sitophilus zeamais and booklice, Liposcelis bostrychophila.Methods: Water-distilled essential oil of M. apelta aerial parts was analyzed by gas chromatography/mass spectrometric (GC/MS) to determine its composition. Insecticidal activities of the essential oil were measured by using topical application/ impregnated filter paper and seal-spaced fumigation.Results: Thirty-six compounds, accounting for 97.75 % of the oil, were identified. The main compounds found were µ-eudesmol (18.65 %), µ-caryophyllene (9.83%), µ-selinene (6.55 %), caryophyllene oxide (6.29 %), bornyl acetate (6.07%), ϒ-eudesmol (5.40 %) and α-selinene (5.06 %). The essential oil showed contact toxicity against adult maize weevils L. bostrychophila with LD50 (lethal dosage, 50 %) value of 46.69 µg/adult and 211.02 µg/cm, respectively. The essential oil also exhibited fumigant toxicity against adult S. zeamais and L. bostrychophila with a LC50 (median lethal concentration) value of 48.42 and 3.21 mg/l, respectively.Conclusion: The study indicates that the essential oil of M. apelta has the potential to be developed into a natural fumigant/insecticide for the control of stored product insects.Keywords: Mallotus apelta, Sitophilus zeamais, Liposcelis bostrychophila, Contact toxicity, Fumigant, Essential oil