Chemical composition and insecticidal activity of the essential oil of Amethystea caerulea L

The essential oil of the aerial parts of Amethystea caerulea L. was obtained from steam distillation and investigated by GC and GC-MS. The main components of the essential oil were morrilol (25.1%), 4-vinylguaiacol (14.3%) and acetoanisole (14.3%), followed by linalool (6.6%), eugenol (5.8%) and α-caryophyllene (5.2%). The essential oil showed pronounced contact toxicity against Drosophila melanogaster L. and maize weevil, Sitophilus zeamais (Motsch.), with LD(50) values of 5.18 and 50.45?μg per adult, respectively. The essential oil also possessed strong fumigant toxicity against the maize weevils with an LC(50) value of 25.39?μg?mL(-1).     

Insecticidal activity of essential oil of Carum Carvi fruits from China and its main components against two grain storage insects

During our screening program for agrochemicals from Chinese medicinal herbs and wild plants, the essential oil of Carum carvi fruits was found to possess strong contact toxicity against Sitophilus zeamais and Tribolium castaneum adults, with LD?? values of 3.07 and 3.29 μg/adult, respectively, and also showed strong fumigant toxicity against the two grain storage insects with LC?? values of 3.37 and 2.53 mg/L, respectively. The essential oil obtained by hydrodistillation was investigated by GC and GC-MS. The main components of the essential oil were identified to be (R)-carvone (37.98%) and D-limonene (26.55%) followed by α-pinene (5.21), cis-carveol (5.01%) and β-myrcene (4.67%). (R)-Carvone and D-limonene were separated and purified by silica gel column chromatography and preparative thin layer chromatography, and further identified by means of physicochemical and spectrometric analysis. (R)-Carvone and D-limonene showed strong contact toxicity against S. zeamais (LD?? = 2.79 and 29.86 μg/adult) and T. castaneum (LD?? = 2.64 and 20.14 μg/adult). (R)-Carvone and D-limonene also possessed strong fumigant toxicity against S. zeamais (LC?? = 2.76 and 48.18 mg/L) and T. castaneum adults (LC?? = 1.96 and 19.10 mg/L).     

Components and insecticidal activity against the maize weevils of Zanthoxylum schinifolium fruits and leaves

In our screening program for new agrochemicals from Chinese medicinal herbs and wild plants, Zanthoxylum schinifolium essential oils were found to possess strong insecticidal activity against the maize weevil Sitophilus zeamais. The essential oils of Z. schinifolium fruits and leaves were extracted via hydrodistillation and investigated by GC and GC-MS. Estragole (69.52%) was the major compound of the essential oil of fresh fruits, followed by linalool (8.63%) and limonene (4.34%) and 94.33% of the total components were monoterpenoids. The main components of the essential oil of fresh leaves were linalool (12.94%), ar-tumerone (8.95%), limonene (6.45%) and elixene (5.43%) and only 50.62% were monoterpenoids. However, the essential oil from purchased fruits contained linalool (33.42%), limonene (13.66%) and sabinene (5.72%), followed by estragole (4.67%), nerol (4.56%) and 4-terpineol (4.27%). Estragole, linalool and sabinene were separated and purified by silica gel column chromatography and preparative thin layer chromatography, and further identified by means of physicochemical and spectrometric analysis. The essential oil from the fresh fruits (LD?? = 15.93 μg/adult) possessed two times more toxicity to the insects compared with that of fresh leaves (LD?? = 35.31 μg/adult). Estragole, linalool and sabinene exhibited contact activity against S. zeamais with LD?? values of 17.63, 13.90 and 23.98 μg/adult, respectively. The essential oils of Z. schinifolium possessed strong fumigant toxicity against S. zeamais adults with LC?? values of 13.19 mg/L (fresh fruits), 24.04 mg/L (fresh leaves) and 17.63 mg/L (purchased fruits). Estragole, linalool and sabinene also exhibited strong fumigant toxicity against the maize weevils with LC?? values of 14.10, 10.46 and 9.12 mg/L, respectively.     

Chemical composition and insecticidal activity against Sitophilus zeamais of the essential oils derived from Artemisia giraldii and Artemisia subdigitata

The aim of this research was to determine the chemical composition and insecticidal activity of the essential oils derived from flowering aerial parts of Artemisia giraldii Pamp. and A. subdigitata Mattf. (Family: Asteraceae) against the maize weevil (Sitophilus zeamais Motsch.). Essential oils of aerial parts of A. giraldii and A. subdigitata were obtained from hydrodistillation and investigated by GC and GC-MS. A total of 48 and 33 components of the essential oils of A. giraldii and A. subdigitata were identified, respectively. The principal compounds in A. giraldii essential oil were β-pinene (13.18%), iso-elemicin (10.08%), germacrene D (5.68%), 4-terpineol (5.43%) and (Z)-β-ocimene (5.06%). 1,8-Cineole (12.26%) and α-curcumene (10.77%) were the two main components of the essential oil of A. subdigitata, followed by β-pinene (7.38%), borneol (6.23%) and eugenol (5.87%). The essential oils of A. giraldii and A. subdigitata possessed fumigant toxicity against the maize weevils with LC50 values of 6.29 and 17.01 mg/L air, respectively. The two essential oils of A. giraldii and A. subdigitata also exhibited contact toxicity against S. zeamais adults with LD50 values of 40.51 and 76.34 μg/adult, respectively. The results indicated that the two essential oils show potential in terms of fumigant and contact toxicity against grain storage insects.     

Fumigant and repellent activities of essential oil extracted from Artemisia dubia and its main compounds against two stored product pests

The major chemical constituents of the essential oil extracted from Artemisia dubia wall. ex Bess. (Family: Asteraceae) were found as terpinolene (19.02%), limonene (17.40%), 2,5-etheno[4.2.2]propella-3,7,9-triene (11.29%), isoelemicin (11.05%) and p-cymene-8-ol (5.93%). Terpinolene and limonene were separated as main components from the essential oil. The essential oil showed fumigant toxicity against Tribolium castaneum and Liposcelis bostrychophila with LC₅₀ values of 49.54 and 0.74 mg/L, respectively. The essential oil and isolated compounds of A. dubia showed repellency activities against both insects. Terpinolene and limonene showed the fumigant toxicity against T. castaneum. Terpinolene showed obvious fumigant toxicity against L. bostrychophila. The results indicated that the essential oil of A. dubia had potential to be developed into natural insecticides for controlling stored product pests.     

The composition and antimicrobial activities of Cyperus conglomeratus, Desmos chinensis var. lawii and Cyathocalyx zeylanicus essential oils

The essential oil compositions of the rhizomes of Cyperus conglomeratus (Cyperaceae) collected from Oman and the leaves of two Annonaceae plants, Desmos chinensis var. lawii and Cyathocalyx zeylanicus collected from India were studied by GC, GC-MS and 13C NMR spectroscopy. Twenty-six compounds, representing 84.4% of the oil were identified in C. conglomeratus, where eugenol (31.3%), alpha-cyperone (10.5%) and cyperotundone (8.4%) were the major compounds. Twelve compounds, constituting 100%, were identified in D. lawii oil, of which benzyl benzoate (58.7%), beta-caryophyllene (23.2%), limonene (4.9%) and alpha-humulene (4.0%) were the major constituents. Thirty-two compounds, comprising 98.0%, were identified in C. zeylanicus oil, of which beta-caryophyllene (21.6%), alpha-pinene (20.4%) and E-beta-ocimene (11.8%) were the major components. The antibacterial and antifungal activities of the oils were tested against a panel of five bacterial and two fungal strains. The oils showed moderate activity against all the tested microbial strains. The minimum inhibitory concentrations of the oils were also determined.     

Chemical composition and insecticidal activity of essential oils of two aromatic plants from Ivory Coast against Bemisia tabaci G. (Hemiptera: Aleyrodidae)

Essential oils of aromatic plants with insecticidal properties are nowadays considered as alternative insecticides to protect cultures from attack by insect pest. The aims of the present work were to evaluate the toxicity of the essential oils vapors of two aromatic plants (Lippia multiflora Mold. and Aframomum latifolium K. Schum) against Bemisia tabaci and to characterize their chemical composition. The highest fumigant toxicity against B. tabaci adults was observed with the L. multiflora oil: by exposure to 0.4 microL/L air, the lethal time inducing 90% mortality (LT90) was below 2 hours for this essential oil whereas it reached 15 h in the case of the A. latifolium oil. Both oils were analyzed by GC-FID and GC-MS on two capillary columns. The oil of L. multiflora contained a majority of oxygenated terpenoids mainly represented by the two acyclic components linalool (46.6%) and (E)-nerolidol (16.5%); the oil of A. latifolium was dominated by hydrocarbonated terpenoids among them beta-pinene (51.6%) and beta-caryophyllene (12.3%) were the two major components.     

Chemical composition and insecticidal activity of the essential oil of Artemisia eriopoda against maize weevil, Sitophilus zeamais

In our screening program for new agrochemicals from local wild plants, Artemisia eriopoda was found to possess insecticidal activities against the maize weevil, Sitophilus zeamais. The essential oil of the aerial parts of A. eriopoda was obtained by hydrodistillation and investigated by GC and GC-MS. The main components of the essential oil are germacrene D (21.6%) and eucalyptol (14.2%). The essential oil possesses fumigant toxicity against S. zeamais adults with a LC50 value of 11.5 mg/L air and also shows contact toxicity against S. zeamais adults with a LD50 value of 24.8 microg/adult, respectively.     

Toxicity of Rhododendron anthopogonoides essential oil and its constituent compounds towards Sitophilus zeamais

The screening of several Chinese medicinal plants for insecticidal principles showed that essential oil of Rhododendron anthopogonoides flowering aerial parts possessed significant toxicity against maize weevils, Sitophilus zeamais. A total of 37 components were identified in the essential oil and the main constituents of the essential oil were 4-phenyl-2-butanone (27.22%), nerolidol (8.08%), 1,4-cineole (7.85%), caryophyllene (7.63%) and γ-elemene (6.10%), followed by α-farnesene (4.40%) and spathulenol (4.19%). Repeated bioactivity-directed chromatographic separation on silica gel columns led us to isolate three compounds, namely 4-phenyl-2-butanone, 1,4-cineole, and nerolidol. 4-Phenyl-2-butanone shows pronounced contact toxicity against S. zeamais (LD?? = 6.98 mg/adult) and was more toxic than either 1,4-cineole or nerolidol (LD?? = 50.86 mg/adult and 29.30 mg/adult, respectively) against the maize weevils, while the crude essential oil had a LD?? value of 11.67 mg/adult. 4-Phenyl-2-butanone and 1,4-cineole also possessed strong fumigant toxicity against the adults of S. zeamais (LC?? = 3.80 mg/L and 21.43 mg/L) while the crude essential oil had a LC?? value of 9.66 mg/L.     

Activity of Schinus areira (Anacardiaceae) essential oils against the grain storage pest Tribolium castaneum

Essential oils extracted from leaves and fruits of Schinus areira (Anacardiaceae) were tested for their repellent, toxic and feeding deterrent properties against Tribolium castaneum (Coleoptera: Tenebrionidae) larvae and adults. A topical application assay was employed for the contact toxicity study and filter paper impregnation for the fumigant assay. A treated diet was also used to evaluate the repellent activity and a flour disk bioassay for the feeding deterrent action and nutritional index alteration. The essential oil of the leaves contained mainly monoterpenoids, with alpha-phellandrene, 3-carene and camphene predominant, whereas that from the fruits contained mainly alpha-phellandrene, 3-carene and beta-myrcene. The leaf essential oil showed repellent effects, whereas that from the fruit was an attractant. Both oils produced mortality against larvae in topical and fumigant bioassays, but fumigant toxicity was not found against adults. Moreover, both essential oils produced some alterations in nutritional index. These results show that the essential oils from S. areira could be applicable to the management of populations of Tribolium castaneum.     

Chemical Composition,Insecticidal, Persistence and Detoxification Enzyme Inhibition Activities of Essential Oil of Artemisia maritima against the Pulse Beetle

Pulse beetle is the major pests of pulses that cause significant loss to grains leads to unfit for consumption and marketing. Indiscriminate use of synthetic pesticides for the control of pulse beetle (Callosobruchus chinensis and Callosobruchus maculatus) led to insect resistance, pesticide residues on grains which affect consumer’s health and environment. Essential oils (EOs) are good alternatives to synthetics due to their safety to the environment and consumers’ health. The main objective of the present study was to explore the chemical composition, fumigant, repellency, ovipositional deterrence, persistence, and detoxification enzyme inhibition of Artemisia maritima essential oil against pulse beetle. Results showed that primary components of the EO were 1,8-Cineole and bornyl acetate. EO showed promising fumigant toxicity to C. chinensis and C. maculatus (LC₅₀ = 1.17 and 0.56 mg/L, respectively) after 48 h. In the repellent assay, EO at 8 mg/L showed 92–96% repellence after 1 h. In ovipositional deterrence assay, EO showed more ovipositional deterrence against C. chinensis (OD₅₀ = 3.30 mg/L) than C. maculatus (OD₅₀ = 4.01 mg/L). Higher concentrations of oil (8 and 6 mg/L) in C. maculatus showed significant inhibition of the glutathione-S-transferase enzyme (7.14 and 5.61 n mol/min/mL, respectively).     

Analysis of the Essential Oil of Elsholtzia ciliate Aerial Parts and Its Insecticidal Activities against Liposcelis bostrychophila

Water‐distilled essential oil from Elsholtzia ciliate (Labiatae) aerial parts at flowering stage was analyzed by gas chromatography/mass spectrometry (GC/MS). Thirty‐six compounds, accounting for 98.3% of the total oil content, were identified, and the main components of the essential oil were dehydroelsholtzia ketone (26.5%), (R)‐carvone (16.6%), elsholtzia ketone (14.6%), and D ‐limonene (4.1%). The essential oil contained higher amounts of monoterpenoids (83.4%) than of sesquiternoids (8.3%). Bioactivity‐directed chromatographic separation of the essential oil on repeated silica gel columns led to the isolation of three monoterpenoids. The essential oil possessed fumigant toxicity against the booklice (Liposcelis bostrychophila) with an LC₅₀ value of 475.2 μg/l, while the isolated constituents, (R)‐carvone, dehydroelsholtzia ketone, and elsholtzia ketone had LC₅₀ values of 417.4, 658.2, and 547.3 μg/l, respectively. The essential oil also exhibited contact toxicity against L. bostrychophila with an LC₅₀ value of 145.5 μg/cm². (R)‐Carvone, dehydroelsholtzia ketone, and elsholtzia ketone exhibited acute toxicity against the booklice with LC₅₀ values of 57.0, 151.5, and 194.1 μg/cm², respectively. The results indicated that the essential oil and the isolated constituents have potential for the development into natural insecticides/fumigants for the control of insects in stored grains.     

Composition and biological potential of essential oil from Thelechitonia trilobata growing in South Africa

Thelechitonia trilobata is regarded as a troublesome weed that grows to form a dense blanket over the soil preventing the growth of other crops in farmland. Although the plant is regarded as a notorious, invasive plant, its chemical composition and biological potential have not been reported. The essential oil was isolated from the fresh leaves of T. trilobata using hydrodistillation. alpha-Pinene (21.6%), alpha-phellendrene (21.0%), limonene (12.8%) and germacrene D (7.5%) were the major constituents of the oil. The essential oil was screened against agricultural pests. The anti-tick properties were tested on Ripicephalus e. ervertsi found on sheep, while repellency, fumigation, and contact toxicity tests were carried out with maize weevils. Except for the contact toxicity test, all other bioassays gave positive results.     

Evaluation of Clausena anisata essential oil from Cameroon for controlling food spoilage fungi and its potential use as an antiradical agent

Investigations were conducted to determine the chemical composition, antifungal and antiradical activities of the essential oil extracted from the fresh leaves of Clausena anisata (Willd.) Hook. F. ex Benth (from Cameroon) against Aspergillus flavus, A. niger, A. parasiticus and Fusarium moniliforme. The essential oil obtained by hydrodistillation was analysed by GC and GC/MS. The disc diffusion method was used to evaluate the fungal growth inhibition at various concentrations of the oil while the antiradical activity of the essential oil was studied by the DPPH (diphenyl picryl hydrazyl) method. The main components obtained were E-ocimenone (15.1%), Z-ocimenone (11.5%), gamma-terpinene (11.4%) and germacrene D (10.9%). After 10 days of incubation on essential oil supplemented medium, the growth of A. flavus, A. niger, A. parasiticus and F. moniliforme were totally inhibited by 4, 5, 5 and 5 mg/mL of C. anisata essential oil, respectively. The antiradical activity of C. anisata essential oil (SC50 = 5.1 g/L) was less than that of butylated hydroxyl toluene (BHT), which was used as the reference compound (SC50 = 0.007 g/L). Results obtained in the present study indicate the possibility of exploiting C. anisata essential oil to fight strains of A. flavus, A. niger, A. parasiticus and F. moniliforme responsible for biodeterioration of stored food products.     

Chemical constituents, antioxidant and antimocrobial activity of essential oil of Pogostemon paniculatus (Willd.)

The essential oil extracted from the leaves of Pogostemon paniculatus (Willd.) Benth. (Lamiaceae), was analysed by gas chromatography-mass spectrometry (GC-MS). Nineteen compounds constituting 85.36% of the total oil were identified in the oil. Patchouli alcohol (30.65%), α-guaiene (10.67%), β-guaiene (9.09%), caryophyllene (8.64%), eicosene (5.27%) were the major constituents present. The essential oil was analysed for antimicrobial activity by disc diffusion assay and minimum inhibition concentration against six bacteria and three fungi. Results showed inhibitory activity against some of the tested microorganisms. The essential oil was also tested for the DPPH free-radical scavenging activity and had an inhibitory concentration (IC(50)) value of 18.5?μg?mL(-1).     

Insecticidal activity of the root bark essential oil of Periploca sepium Bunge and its main component

During our screening programme for agrochemicals from Chinese medicinal herbs, the root bark essential oil of Periploca sepium was found to possess strong contact toxicity against the fruit flies, Drosophila melanogaster with a LD(50) value of 1.22?μg/adult. The main component of the essential oil was identified to be 2-hydroxy-4-methoxy-benzaldehyde (78.8%), followed by linalool (2.8%) and (-)-α-terpineol (2.7%). The 2-hydroxy-4-methoxy-benzaldehyde was further isolated and identified by bioassay-directed fractionation. The compound showed strong contact toxicity against D. melanogaster and the maize weevil (Sitophilus zeamais) with LD(50) values of 1.47 and 6.99?μg/adult, respectively.     

Composition and antioxidant activity of essential oil of pimento (Pimenta dioica (L) Merr.) from Jamaica

The composition and antioxidant activity of the essential oil obtained through hydrodistillation of pimento berry [Pimenta dioica (L.) Merr] samples, namely P1 and P2, sourced from Jamaica, were studied. The chemical composition was analysed by GC and GC-MS methods. The antioxidant activities of the oils were evaluated in terms of their free-radical-scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical cation and superoxide anion (?[image omitted]). Total phenolic content, total reducing power and metal-chelating capacity of the oils were also estimated. Forty-five constituents were identified. The major compound identified was eugenol (74.71%, 73.35%), followed by methyl eugenol (4.08%, 9.54%) and caryophyllene (4.90%, 3.30%). The antioxidant assays showed that the oils possess very high radical scavenging activities (DPPH IC(50) 4.82 ± 0.08, 5.14 ± 0.11 μg mL(-1), ABTS IC(50) 2.27 ± 0.16, 2.94 ± 0.03 μg mL(-1), superoxide IC(50) 17.78 ± 1.31, 20.65 ± 0.82 μg mL(-1)). The metal chelating capacities (IC(50) 83.62 ± 2.10, 101.77 ± 1.01 μg mL(-1)) and reducing power were also very high. The results show that the essential oils possess significant antioxidant activity which is comparable to that of pure eugenol. Therefore the oil can be utilised as a natural antioxidant which gives good flavour as well as health benefits.     

Antifungal effect of the essential oil of Thymus broussonetii Boiss endogenous species of Morocco

The aim of the study was to determine the antifungal effects of the essential oil of Thymus broussonetii Boiss (EOT), an endemic plant in Morocco against Candida albicans, Aspergillus fumigatus and the dermatophytes. EOT was extracted by steam distillation. A suspension of up to 500?μL of C. albicans at a concentration of 10??CFU?mL?1 and A. fumigatus at a concentration of 101??spores?mL?1 were inhibited by 20?μL of EOT incorporated in tubes containing 4 mL of Sabouraud broth. In Sabouraud-chloramphenicol agar slants containing different concentrations of essential oil, 5?×?10? A. fumigatus spores were inhibited by 6?μL (0.0015?mL?mL?1) of the EOT. It has shown good anti-C. albicans and anti-A. fumigatus activity. All the dermatophytes tested were inhibited by 3?μL (0.00075?mL?mL?1) of EOT; the latter has the potential to be a good alternative to the conventional antifungal drugs which are usually expensive and with high toxicity.     

Evaluation of jatropha oil to produce poly(3-hydroxybutyrate) by Cupriavidus necator H16

Jatropha oil, a non-edible vegetable oil, may be an alternative substrate to food-grade oils for bioplastic production. Jatropha oil contains 93.9% palmitic acids, oleic acids and linoleic acids. High P(3HB) accumulation of 87 wt% from 13.1 g/L of cell dry weight (CDW) was obtained by Cupriavidus necator H16 when 12.5 g/L of jatropha oil and 0.54 g/L of urea were used. Lipase activity increased in the initial stages of P(3HB) production, when 1 g/L of jatropha oil was added to the preculture medium. Addition of oil in preculture did not affect final CDW or P(3HB) accumulation. P(3HB) production in a 10 L lab-scale fermenter gave a yield of 0.78 g P(3HB) per g jatropha oil used after 48 h. For the first time, this study proved that jatropha oil is a feasible and excellent carbon source for P(3HB) biosynthesis by C. necator H16 with potential for large-scale production. The toxins in jatropha oil did not affect the P(3HB) biosynthesis.     

Naturally occurring phytotoxins in allelopathic plants help reduce herbicide dose in wheat

Field studies were carried out to evaluate the influence of allelopathic plant water extracts applied alone or tank-mixed with a reduced herbicide dose on the weeds of wheat. Water extracts of sorghum (Sorghum bicolor (L.) Moench.)?+?sunflower (Helianthus annuus L.)?+?mulberry (Morus alba L.) were used alone (each at 20?L?ha(-1)) or combined with iodo?+?mesosulfuron (3.6 and 7.2 g active ingredient (a.i.) ha(-1); 25 and 50% of the recommended dose, respectively). The recommended dose of herbicide, a weedy check and a weed-free treatment were included for comparison. Allelopathic water extracts alone suppressed the density of canary grass (Phalaris minor Retz.) and wild oat (Avena fatua L.) by 34-42%, and dry weight by 59-67%. The mixture of allelopathic plant water extracts combined with reduced doses of iodo?+?mesosulfuron gave weed control equal to the recommended dose of the herbicide. Integration of plant water extracts with reduced herbicide rates provide effective weed control and a wheat yield comparable to using the recommended herbicide dose.