Abstract

The aim of this research was to determine chemical composition and insecticidal activity of the essential oil of Pelargonium hortorum Bailey (Geraniaceae) flowering aerial parts against the booklouse (Liposcelis bostrychophila Badonnel) and maize weevils (Sitophilus zeamais Motschulsky). The essential oil of P. hortorum flowering aerial parts was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 36 components of the essential oil were identified. The principal compounds in the essential oil were 1,8-cineole (23.01%), α-terpineol (13.22%), α-pinene (8.13%) and camphor (8.12%) followed by 4-terpineol (4.63%), β-myrcene (4.56%) and β-caryophyllene (4.08%). The essential oil exhibited contact toxicity against L. bostrychophila and S. zeamais with LD₅₀ values of 149.78 μg/cm² and 14.41 µg/adult, respectively. The essential oil also possessed fumigant toxicity against L. bostrychophila and S. zeamais adults with LC₅₀ values of 1.31 mg/L air and 7.22 mg/L air, respectively. The results indicated that the essential oil of P. hortorum showed potential in terms of contact and fumigant toxicity against grain storage insects.

Key words: Pelargonium hortorum, Liposcelis bostrychophila, Sitophilus zeamais, contact toxicity, fumigant, essential oil composition.