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 ß-pinene (13.18%), iso-elemicin (10.08%), germacrene D (5.68%), 4-terpineol (5.43%) and (Z)-ß-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 ß-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.

Antifeedants from Chinese medicinal herb, Erythrina variegata var. orientalis, against maize weevil Sitophilus zeamais.

The screening for insecticidal principles from several Chinese medicinal herbs showed that the stem bark of Erythrina variegata var. orientalis possessed significant feeding deterrence against maize weevils, Sitophilus zeamais. Bioassay-directed fractionation of the stem bark extract of E. variegata var. orientalis resulted in the isolation of two alkaloids, identified as erysopine and erysovine from their spectroscopic data. Erysopine and erysovine possessed antifeedant activity against S. zeamais adults with EC50 values of 108.5 and 89.7 ppm, respectively.

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.

Evaluation of Essential Oil and its Three Main Active Ingredients of Chinese Chenopodium ambrosioides (Family: Chenopodiaceae) against Blattella germanica.

BACKGROUND: The efficacy of essential oil of Chenopodium ambrosioides flowering aerial parts and its three main active ingredients was evaluated against Blattella germanica male adults. METHODS: Composition of essential oil was determined by GC-MS. Topical application bioassay was used to evaluate contact toxicity of essential oil and three main components. Fumigant toxicity of essential oil and its main components was measured using a sealed space method. RESULTS: Twenty-two components were identified in the essential oil and the main components were (Z)-ascaridole (29.7%), isoascaridole (13.0%), ρ-cymene (12.7%) and piperitone (5.0%). The essential oil and (Z)-ascaridole, isoascaridole and ρ-cymene possessed fumigant toxicity against male German cockroaches with LC(50) values of 4.13, 0.55, 2.07 and 6.92 mg/L air, respectively. Topical application bioassay showed that all the three compounds were toxic to male German cockroaches and (Z)-ascaridole was the strongest with a LD(50) value of 22.02 µg/adult while the crude oil with a LD(50) value of 67.46 µg/adult. CONCLUSION: The essential oil from Chinese C. ambrosioides and its three main active ingredients may be explored as natural potential insecticides in the control of cockroaches.

GC-MS analysis of insecticidal essential oil of flowering aerial parts of Saussurea nivea Turcz.

BACKGROUND: Several species from Saussurea have been used in the traditional medicine, such as S. lappa, S. involucrate, and S. obvallata. There is no report on medicinal use of S. nivea. The aim of this research was to determine chemical composition and insecticidal activity of the essential oil of S. nivea Turcz (Asteraceae) aerial parts against maize weevils (Sitophilus zeamais Motschulsky) for the first time. RESULTS: Essential oil of S. nivea flowering aerial parts was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). A total of 43 components of the essential oil of S. nivea were identified. The principal compounds in the essential oil were (+)-limonene (15.46%), caryophyllene oxide (7.62%), linalool (7.20%), α-pinene (6.43%), ß-pinene (5.66%) and spathulenol (5.02%) followed by ß-eudesmoll (4.64%) and eudesma-4,11-dien-2-ol (3.76%). The essential oil of S. nivea exhibited strong contact toxicity against S. zeamais with an LD50 value of 10.56 µg/adult. The essential oil also possessed fumigant toxicity against S. zeamais with an LC50 value of 8.89 mg/L. CONCLUSION: The study indicates that the essential oil of S. nivea flowering aerial parts has a potential for development into a natural insecticide/fumigant for control of insects in stored grains.

Essential oil composition and larvicidal activity of Saussurea lappa roots against the mosquito Aedes albopictus (Diptera: Culicidae).

In recent years, uses of environment friendly and biodegradable natural insecticides of plant origin have received renewed attention as agents for vector control. The aim of this research was to determine larvicidal activity of the essential oil derived from roots of Saussurea lappa (Compositae) and the isolated constituents against the larvae of the Culicidae mosquito Aedes albopictus. Essential oil of S. lappa roots was obtained by hydrodistillation and analyzed by gas chromatography (GC) and GC-mass spectrometry (MS). A total of 39 components of the essential oil of S. lappa roots were identified. The essential oil has higher content of (79.80%) of sesquiterpenoids than monoterpenoids (13.25%). The principal compounds in S. lappa essential oil were dehydrocostus lactone (46.75%), costunolide (9.26%), 8-cedren-13-ol (5.06%), and α-curcumene (4.33%). Based on bioactivity-directed fractionation, dehydrocostus lactone and costunolide were isolated from S. lappa essential oil. Dehydrocostus lactone and costunolide exhibited strong larvicidal activity against A. albopictus with LC(50) values of 2.34 and 3.26 µg/ml, respectively, while the essential oil had an LC(50) value of 12.41 µg/ml. The result indicated that the essential oil of S. lappa and the two isolated constituents have potential for use in control of A. albopictus larvae and could be useful in search of newer, safer and more effective natural compounds as larvicides.

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 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.

Insecticidal compounds from the essential oil of Chinese medicinal herb Atractylodes chinensis.

BACKGROUND: In a screening programme for new agrochemicals from Chinese medicinal herbs, the essential oil of Atractylodes chinensis (DC.) Koidz was found to possess strong insecticidal activity against the common vinegar fly, Drosophila melanogaster L. The essential oil was extracted via hydrodistillation, and its constituents were determined by GC-MS analysis. RESULTS: The main components of A. chinensis essential oil were ß-eudesmol (21.05%), ß-selinene (11.75%), γ-elemene (7.16%) and isopetasam (5.36%). Bioactivity-directed chromatographic separation on repeated silica gel columns led to the isolation of five compounds, namely atractylon, α-elemol, ß-eudesmol, hinesol and ß-selinene. ß-Selinene, α-elemol and hinesol showed pronounced contact toxicity against D. melanogaster adults, with LD(50) values of 0.55, 0.65 and 0.71 µg adult(-1) respectively. Atractylon and ß-eudesmol were also toxic to the fruit flies (LD(50) = 1.63 and 2.65 µg adult(-1) respectively), while the crude oil had an LD(50) value of 2.44 µg adult(-1) . CONCLUSION: The findings suggested that the essential oil of Atractylodes chinensis and its active constituents may be explored as natural potential insecticides.

Toxicity of Schizonpeta multifida essential oil and its constituent compounds towards two grain storage insects.

BACKGROUND: The essential oil derived from the flowering aerial parts of Schizonpeta multifida was investigated for insecticidal activity against two grain storage insects, maize weevil (Sitophilus zeamais) and red flour beetle (Tribolium castaneum). RESULTS: The main constituents of the essential oil were menthone (40.34%) and pulegone (26.87%), followed by D-limonene (5.81%) and isomenthone (5.14%). Bioactivity-directed chromatographic separation on repeated silica gel columns led to the isolation of menthone and pulegone. Pulegone showed pronounced contact toxicity against S. zeamais and T. castaneum adults (7 day LD(50)= 4.46 and 1.55 µg per adult respectively) and was more toxic than menthone (7 day LD(50)=33.47 and 2.67 µg per adult respectively), while the crude essential oil had 7 day LD(50) values of 30.17 and 2.75 µg per adult respectively. Pulegone also displayed strong fumigant toxicity against S. zeamais and T. castaneum adults (7 day LC(50)=3.47 and 11.56 mg cm(-3) respectively) and was again more toxic than menthone (7 day L(50) =10.32 and 31.25 mg cm(-3) respectively), while the crude essential oil had 7 day LC(50) values of 8.33 and 26.41 mg cm(-3) respectively. CONCLUSION: The essential oil of S. multifida and its two main components may have potential to be developed as new natural fumigants/insecticides for the control of stored product insects.

Composition of essential oil of Chinese Chenopodium ambrosioides and insecticidal activity against maize weevil, Sitophilus zeamais.

BACKGROUND: In a screening programme for new agrochemicals from Chinese medicinal herbs, Chenopodium ambrosioides L. was found to possess strong fumigant activity against the maize weevil Sitophilus zeamais (Motsch.). Essential oil of C. ambrosioides was obtained by hydrodistillation, and the constituents were determined by GC-MS analysis. The active compounds were isolated and identified by bioassay-directed fractionation. RESULTS: Five active compounds [(Z)-ascaridole, 2-carene, ρ-cymene, isoascaridole and α-terpinene] were isolated and identified from the essential oil from Chinese C. ambrosioides. The LC50 values (fumigation) of the crude essential oils and the active compound (Z)-ascaridole against S. zeamais adults were 3.08 and 0.84 mg L⁻¹ air respectively. The LD50 values (contact toxicity) of the crude essential oil and (Z)-ascaridole against S. zeamais adults were 2.12 and 0.86 µg g⁻¹ body weight respectively. CONCLUSION: The findings suggested that the essential oil of Chenopodium ambrosioides and its main active constituent, (Z)-ascaridole, may be explored as a natural potential fumigant.

Toxicity of the essential oil of Illicium difengpi stem bark and its constituent compounds towards two grain storage insects.

During our screening program for new agrochemicals from Chinese medicinal herbs, the essential oil of Illicium difengpi stem bark was found to possess strong insecticidal activities against the maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) and red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae). A total of 37 components of the essential oil of I. difengpi were identified. The main components of the essential oil were safrole (23.61%), linalool (12.93%), and germacrene D (5.35%). Bioactivities-directed chromatographic separation on repeated silica gel columns led to the isolation of two compounds: safrole and linalool. Safrole showed pronounced contact toxicity against both insect species and (LD50 = 8.54 for S. zeamais; 4.67 µg/adult for T. castaneum) and was more toxic than linalool (LD50 = 24.88 for S. zeamais; 8.12 µg/adult for T. castaneum). The essential oil acting against the two species of insects showed LD50 values of 13.83 and 6.33 µg/adult, respectively. Linalool also possessed strong fumigant toxicity against both insect species (LC50 = 10.02 for S. zeamais; 9.34 mg/L for T. castaneum) and was more toxic than safrole (LD50 = 32.96 and 38.25 mg/L), while the crude essential oil acting against the two species of insects showed LC50 values of 14.62 and 16.22 mg/L, respectively. These results suggest that the essential oil of I. difengpi stem bark and the two compounds may be used in grain storage to combat insect pests.

Chemical composition and toxicity against Sitophilus zeamais and Tribolium castaneum of the essential oil of Murraya exotica aerial parts.

In our screening program for new agrochemicals from Chinese medicinal herbs, Murraya exotica was found to possess insecticidal activity against the maize weevil, Sitophilus zeamais and red flour beetle, Tribolium castaneum. The essential oil of aerial parts of M. exotica was obtained by hydrodistillation and investigated by GC and GC-MS. The main components of M. exotica essential oil were spathulenol (17.7%), alpha-pinene (13.3%), caryophyllene oxide (8.6%), and alpha-caryophyllene (7.3%). Essential oil of M. exotica possessed fumigant toxicity against S. zeamais and T. castaneum adults with LC(50) values of 8.29 and 6.84 mg/L, respectively. The essential oils also show contact toxicity against S. zeamais and T. castaneum adults with LD(50) values of 11.41 and 20.94 microg/adult, respectively.

Insecticidal activity and chemical composition of the essential oils of Artemisia lavandulaefolia and Artemisia sieversiana from China.

In our screening program for new agrochemicals from local wild plants, Artemisia lavandulaefolia and A. sieversiana were found to possess insecticidal activity against the maize weevil Sitophilus zeamais. The essential oils of the aerial parts of the two plants were obtained by hydrodistillation and analyzed by GC and GC/MS. The main components of A. lavandulaefolia oil were caryophyllene (15.5%), beta-thujone (13.8%), eucalyptol (13.1%), and beta-farnesene (12.3%), and the principal compounds identified in A. sieversiana oil were eucalyptol (9.2%), geranyl butyrate (9.2%), borneol (7.9%), and camphor (7.9%). The essential oils of A. lavandulaefolia and A. sieversiana possessed fumigant toxicity against S. zeamais adults with LC(50) values of 11.2 and 15.0 mg/l air, respectively. Both essential oils also showed contact toxicity against S. zeamais adults with LD(50) values of 55.2 and 112.7 microg/adult, respectively.

Chemical composition and insecticidal activity against Sitophilus zeamais of the essential oils of Artemisia capillaris and Artemisia mongolica.

In our screening program for new agrochemicals from local wild plants, Artemisia capillaris and A. mongolica were found to possess insecticidal activity against the maize weevil, Sitophilus zeamais. The essential oils of aerial parts of the two plants were obtained by hydrodistillation and were investigated by GC and GC-MS. The main components of A. capillaris essential oil were 1,8-cineole (13.75%), germacrene D (10.41%), and camphor (8.57%). The main constituents of A. mongolica essential oil were alpha-pinene (12.68%), germacrene D (8.36%), and gamma-terpinene (8.17%). Essential oils of A. capillaris and A. mongolica possess fumigant toxicity against S. zeamais adults with LC50 values of 5.31 and 7.35 mg/L respectively. The essential oils also show contact toxicity against S. zeamais adults with LD50 values of 105.95 and 87.92 microg/adult, respectively.

Feeding deterrents from Zanthoxylum schinifolium against two stored-product insects.

Screening for insecticidal principles from several Chinese medicinal herbs showed that the fruit pericarp of Zanthoxylum schinifolium possessed significant feeding deterrence against two stored-product insects (Tribolium castaneum and Sitophilus zeamais). From the methanol extract, two feeding deterrents were isolated by bioassay-guided fractionation. The compounds were identified as schinifoline and skimmianine from their spectroscopic data. Schinifoline has feeding deterrent activity against T. castaneum and S. zeamais adults with EC(50) values of 47.8 and 85.6 ppm respectively. Skimmianine possess feeding deterrent activity against T. castaneum and S. zeamais adults with EC(50) values of 75.7 and 129.7 ppm respectively.