Search

Purpose: To determine the insecticidal properties of essential oil from Mosla soochowensis aerial parts against two insect pests, Sitophilus zeamais and Tribolium castaneum. Methods: Hydro-distillation of M. soochowensis was used to extract the essential oil. Gas chromatography/mass spectrometry (GC/MS) analysis was performed, and the contact (topical application) and fumigant toxicity (sealed space) of the essential oil were evaluated. Results: Thirty-nine chemical compounds were identified by GC-MS analysis of M. soochowensis essential oil. The major components are β-caryophyllene (12.82 %), spatulenol (6.34 %), β-eudesmol (6.26 %), carvone (6.12 %), α-thujone (5.12 %), γ-eudesmol (4.86 %), α-cedrol (4.23 %), and α- caryophyllene (4.04 %). The plant essential oil exerted contact toxicity against adults of S. zeamais and T. castaneum (median lethal concentration (LC50), 25.45 and 10.23 μg/adult, respectively). Moreover, the essential oil exhibited pronounced fumigant toxicity towards adults of both species (LC50 12.19 and 10.26 mg/L air, respectively). Conclusion: These results show that M. soochowensis essential oil can be used in development of safer and more natural and effective fumigants/insecticides for stored products. [ABSTRACT FROM AUTHOR]

Purpose: To investigate contact and fumigant toxicity of the essential oil of Bidens frondosa and its isolated constituents against booklice (Liposcelis bostrychophila). Methods: The essential oil of B. frondosa was obtained by hydro-distillation and analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) with HP-5MS column. The active constituents were purified from the oil by bioactivity-guided fractionation. Contact (impregnated filter paper method) and fumigant toxicity (sealed space) of the oil and its isolates were determined. Results: Thirty-two compounds, representing 98.88 % of the total oil, were determined and the major constituents of the essential oil were caryophyllene oxide (20.50 %), borneol (17.66 %), 4-terpineol (17.26 %), and ß-cedrene (6.94 %). The essential oil displayed fumigant toxicity against booklice, with a median lethal concentration (LC50) of 507.35 µg/L while the isolated constituents, borneol and 4-terpineol, had LC50 values of 2.20 mg/L and 335.24 µg/L against booklice, respectively. The essential oil also exhibited contact toxicity against L. bostrychophila with an LC50 value of 210.73 µg/cm². Borneol, caryophyllene oxide, β-cedrene, and 4-terpineol showed acute toxicity against booklice with LC50 of 98.04, 84.62, 458.79 and 211.35 µg/cm², respectively. Conclusion: The results suggest that the essential oil and its isolates possess potential for cultivation into natural insecticides or fumigants, for control of insects in stored grains. [ABSTRACT FROM AUTHOR]

Water-distilled essential oil from Clinopodium chinense (Labiatae) aerial parts at the flowering stage was analyzed by gas chromatography-mass spectrometry. Thirty-five compounds, accounting for 99.18% of the total oil, were identified, and the main components of the essential oil of C. chinense were spathulenol (18.54%), piperitone (18.9%), caryophyllene (12.04%), and bomyl acetate (8.14%). Based on bioactivity-directed fractionation, bomyl acetate, caryophyllene, and piperitone were identified from the essential oil. The essential oil possessed fumigant toxicity against booklice (Liposcelis bostrychophila) with a 50% lethal concentration (LC50) value of 423.39 pg/liter, while the isolated constituents, bornyl acetate and piperitone, had LC50 values of 351.69 and 311.12 pg/l iter against booklice, respectively. The essential oil also exhibited contact toxicity against L. bostiychophila with an LC50 value of 215.25 µg/cm². Bomyl acetate, caryophyllene, and piperitone exhibited acute toxicity against booklice with LC50 values of 321.42, 275.00, and 139.74 µg/cm², respectively. The results indicated that the essential oil and its isolated constituents have potential for development into natural insecticides or fumigants for control of insects in stored grains. [ABSTRACT FROM AUTHOR]

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 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. [ABSTRACT FROM AUTHOR]

Purpose: To determine larvicidal activity of essential oil derived from Clinopodium gracile (Benth.) Matsum. (Labiatae) aerial parts against the larvae of Aedes albopictus Skuse. Methods: Essential oil of C. gracile aerial parts was obtained by hydrodistillation and analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The activity of the essential oil was evaluated, using World Health Organization (WHO) procedures, against the fourth larvae of A. albopictus for 24 h and larval mortality recorded at a various essential oil concentrations ranging from 12.5 - 200.0 μg/mL. Results: A total of 34 components of the essential oil of C. gracile were identified. The essential oil has higher content of sesquiterpenoids (70.49 %) than monoterpenoids (12.21 %). The other principal compounds of the essential oil were germacrene D (20.59 %), nootkatone (8.22 %), morillol (7.74 %), β- elemene (7.38 %), α-bergamotene (6.08 %), cis-β-farnesene (5.47 %) and caryophyllene (5.17 %). The essential oil exhibited larvicidal activity against A. albopictus with a median lethal concentration (LC50) of 42.56 μg/mL. Conclusion: The findings obtained indicate that the essential oil of C. gracile has potentials for use in the control of A. albopictus larvae and could be useful in the search for new, safer and more effective natural compounds as larvicides. [ABSTRACT FROM AUTHOR]