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 β-eudesmol (18.65 %), β-caryophyllene (9.83%), β-selinene (6.55 %), caryophyllene oxide
(6.29 %), bornyl acetate (6.07%), γ-eudesmol (5.40 %) and α-selinene (5.06 %). The essential oil
showed contact toxicity against adult maize weevils
L. bostrychophila with LD
50 (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 LC
50 (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.
