Essential Oil of <i>Amomum maximum</i> Roxb. and Its Bioactivities against Two Stored-Product Insects

Amomum maximum Roxb. is a perennial herb distributed in South China and Southeast Asia. The objective of this work was to analyze the chemical constituents and assess insecticidal and repellent activities of the essential oil from Amomum maximum fruits against Tribolium castaneum (Herbst) and Liposcelis bostrychophila (Badonnel). The essential oil was obtained by hydrodistillation and analyzed by gas chromatography-flame ionization detector and gas chromatography-mass spectrometry. The main components of the essential oil were identified to be β-pinene (23.39%), β-caryophyllene (16.43%), α-pinene (7.55%), sylvestrene (6.61%) and ç-cadinene (4.19%). It was found that the essential oil of A. maximum fruits possessed contact and fumigant toxicities against T. castaneum adults (LD50 = 29.57 μg/adult and LC50 = 23.09 mg/L air, respectively) and showed contact toxicity against L. bostrychophila (LD50 = 67.46 μg/cm2). Repellency of the crude oil was also evaluated. After 2 h treatment, the essential oil possessed 100% repellency at 78.63 nL/cm2 against T. castaneum and 84% repellency at 63.17 nL/cm2 against L. bostrychophila. The results indicated that the essential oil of A. maximum fruits had the potential to be developed as a natural insecticide and repellent for control of T. castaneum and L. bostrychophila.