Purpose: To investigate the chemical composition and insecticidal activity of the essential oil of the
aerial parts of
Ainsliaea fragrans
against maize weevils (
Sitophilus zeamais
).
Methods: The essential oil of
A. fragrans aerial parts was obtained by hydrodistillation and analyzed by
gas chromatography (GC) and gas chromaotography-mass spectrometry (GC-MS). Contact toxicity of
the essential oil and its major constituents was determined by topical application against
S. zeamais.
Results: A total of 30 components of the essential oil were identified. The major constituents were
myristicin (41.3 %), elemicine (11.9 %), cis-isosafrole (11.5 %), borneol (9.1 %) and caryophyllene (8.8
%). The essential oil of
A. fragrans exhibited contact toxicity against
S. zeamais with LC
50 value of 50.7
μg/adult. Elemicine possessed the strongest contact toxicity (LC
50 = 13.5 μg/adult) while cis-isosafrole,
myristicin, caryophyllene and borneol had LC
50 values of 31.2 μg/adult, 43.4 μg/adult, 57.9 μg/adult, and
98.4 μg/adult, respectively.
Conclusion: The study indicates that the essential oil of
A. fragrans aerial parts and its major
constituents have a potential for development into natural insecticides for the control of grain storage
insects.
