• Journal of Applied Biological Chemistry
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• v.48 no.1
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• pp.26-28
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• 2005

Evaluation of larvicidal activities of Chamaecyparis obtusa and Thuja orientalis oils against 4th-instar larvae of Aedes aegypti and Culex pipiens pallens revealed larvicidal activities of leaf oils extracted from C. obtusa and T. orientalis were significantly higher than those of stem, fruit, and seed oils. Strong mortality was observed in age class II of C. obtusa and T. orientalis against Ae. aegypti and Cx. pipiens pallens larvae. These results show both leaf part and age class II of C. obtusa and T. orientalis have strong larvicidal activity against Ae. aegypti and Cx. pipiens pallens. Leaf oils of C. obtusa and T. orientalis leaves show promise as natural larvicides against Ae. aegypti and Cx. pipiens pallens.

• International Journal of Industrial Entomology and Biomaterials
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• v.15 no.1
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• pp.87-91
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• 2007

A diverse kind of environment-friendly agricultural materials(EFAM) for the control of insect pests is on the market. These EFAMs are a part of essential sources for the accomplishment of successful, sustainable, and environment-friendly agriculture. Thus, accurate information of these EFAMs is one that required for the success of environment-friendly agriculture, but, in reality, still appropriate information is absolutely in shortage. In this study, we, therefore, tested the efficacy of commercial EFAMs against two lepidopteran insect larvae, the diamondback moth Plutella xylostella(Lepidoptera: plutellidae) and the tobacco cutworm Spodoptera litura(Lepidoptera: Noctuidae). After the two insect pests were successfully stabilized in indoor environment the larvicidal activity was tested at $24{\pm}1^{\circ}C$, relative humidity(RH) of $60{\pm}5%$, and a photoperiod of 16L:8D, and mortality was determined 48 hrs after EFAMs are treated. The EFAMs that showed more than 90% of larvicidal activity were each six among 16 against both P. xylostella and S. litura and only three of them showed consistent larvicidal activity against both species, signifying species specificity of EFAMs and importance of selection of proper EFAMs depending on target insect pest.

• BMB Reports
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• v.40 no.2
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• pp.163-171
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• 2007

Functional elements of the conserved helix 7 in the poreforming domain of the Bacillus thuringiensis Cry $\delta$- endotoxins have not yet been clearly identified. Here, we initially performed alanine substitutions of four highly conserved aromatic residues, $Trp^{243}$, $Phe^{246}$, $Tyr^{249}$ and $Phe^{264}$, in helix 7 of the Cry4Ba mosquito-larvicidal protein. All mutant toxins were overexpressed in Escherichia coli as 130-kDa protoxins at levels comparable to the wild-type. Bioassays against Stegomyia aegypti mosquito larvae revealed that only W243A, Y249A or F264A mutant toxins displayed a dramatic decrease in toxicity. Further mutagenic analysis showed that replacements with an aromatic residue particularly at $Tyr^{249}$ and $Phe^{264}$ still retained the high-level toxin activity. In addition, a nearly complete loss in larvicidal activity was found for Y249L/F264L or F264A/ Y249A double mutants, confirming the involvement in toxicity of both aromatic residues which face towards the same direction. Furthermore, the Y249L/F264L mutant was found to be structurally stable upon toxin solubilisation and trypsin digestion, albeit a small change in the circular dichroism spectrum. Altogether, the present study provides for the first time an insight into the highly conserved aromaticity of $Tyr^{249}$ and $Phe^{264}$ within helix 7 playing an important role in larvicidal activity of the Cry4Ba toxin.

• Applied Biological Chemistry
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• v.37 no.6
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• pp.503-508
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• 1994

Methanol extracts from 45 species of oriental medicinal plants belonging to 17 families were subjected to a screening test for their larvicidal and antifeeding activities against two species of lepidopteran larvae, diamondback moth (Plutella xylostella L.) and tobacco cutworm (Spodoptera litura F.) by a leaf-dipping method. At a concentration of 8,000 ppm, methanol extract of Corydalis turrschaninovii roots only was found to have potent larvicidal activity against S. litura. At 5,000 ppm, strong antifeeding activity against both larvae was observed from the extracts of Clerodendron trichotomum, C. trichotomum var. esculentum, Inura helenium, Arctium lappa, Artemisia messerschmidtiana, Anthriscus sylvestris, Angelica dahurica, and C. turrschaninovii.

• Korean journal of applied entomology
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• v.35 no.2
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• pp.153-158
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• 1996

Methanol extracts from 79 domestic plant species in 41 families and the crude oil of one Japanese plant species were tested for their larvicidal activities against Thecodiplosis japonensis Uchida et Inouye, using filter paperimpregnated and insect-dipping methods. In a test with 10 mgtpaper, strong larvicidal activity (>90% mortality) was obtained from the extracts of roots from three domestic plants belonging to Ranunculaceae (Aconitum pseudo- leave var. eretum, A. carmichaeli and Clematis florida) and the crude oil of sawdust from a Japanese plant, Thujopsis dolabrata var. hondai (Cupressaceae). However, only the crude oil from the Thujopsis sawdust revealed strong larvicidal activity when tested with 5,000 ppm by insect-dipping method. It is concluded that the Thujopsis sawdust-derived materials could be useful as a new control agent against T. japonensis.

• BMB Reports
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• v.34 no.5
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• pp.402-407
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• 2001

Based on the currently proposed toxicity model for the different Bacillus thuringiensis Cry $\delta$-endotoxins, their pore-forming activity involves the insertion of the ${\alpha}4-{\alpha}5$ helical hairpin into the membrane of the target midgut epithelial cell. In this study, a number of polar or charged residues in helix 4 within domain I of the 65-kDa dipteranactive Cry11A toxin, Lys-123, Tyr-125, Asn-128, Ser-130, Gln-135, Arg-136, Gln-139 and Glu-141, were initially substituted with alanine by using PCR-based directed mutagenesis. All mutant toxins were expressed as cytoplasmic inclusions in Escherichia coli upon induction with IPTG. Similar to the wild-type protoxin inclusion, the solubility of each mutant inclusion in the carbonate buffer, pH 9.0, was relatively low When E. coli cells, expressing each of the mutant proteins, were tested for toxicity against Aedes aegypti mosquito-larvae, toxicity was completely abolished for the alanine substitution of arginine at position 136. However, mutations at the other positions still retained a high level of larvicidal activity Interestingly, further analysis of this critical arginine residue by specific mutagenesis showed that conversions of arginine-136 to aspartate, glutamine, or even to the most conserved residue lysine, also abolished the wild-type activity The results of this study revealed an important determinant in toxin function for the positively charged side chain of arginine-136 in helix 4 of the Cry11A toxin.

• Korean journal of applied entomology
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• v.33 no.4
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• pp.225-229
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• 1994

The methanol extracts from 30 species of oriental medicinal plants belonging to 24 families were tested for their lhicidal and antifeeding activit~es against diamondback moth (Plutello xylostella L) and tobacco cutworn (Spodoptera litura F.) by a leaf-dipping method at a concentration of 5, 000 ppm. The methanol extract from Copti chinensis only showed a potent larvicidal activity against P xylostello. Strong antifeeding activity against P. xylostello was observed from the extmds from Platycodon grandiflorurn, Codonopsis pilosula, Asomm sieboldii, Rhus chinensis and Uthospermum erythrorhizon And a potent antifeeding activity against S. liturn was obtained from Akebia quinata and Equlsetum hyemale extracts. A significant antifeeding activity against both species was obtained from R chinensis and C. chinensis extracts.

• Journal of the Korean Wood Science and Technology
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• v.44 no.4
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• pp.494-504
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• 2016

Eucalyptus oils are widely used as spices, perfume industrial materials, food flavorings, and medicines. Several types of Eucalyptus oils also have insecticidal activity and as carminative. This study investigated the chemical composition, insecticidal (larvicidal and repellent) activity of E. urophylla oil against filarial mosquito Culex quinquefasciatus. E. urophylla oil was obtained from fresh leaves by water-steam distillation with oil yield 1.08%. E. urophylla oil in this study had no color (clear), has odor (typical eucalyptus), with specific gravity 0.941; refractive index 1.465; miscibility in 70% ethanol 1 : 3; and optical rotation (-) $5.83^{\circ}$. The major compounds of the oil were ${\alpha}$-pinene (11.73%), 1,8-cineole (49.86%), ${\beta}$-ocimene (6.25%), ${\gamma}$-terpinene (9.11%), and ${\alpha}$-terpinyl acetate (7.63%). The result showed the excellent insecticide activity against C. quinquefasciatus. The oil provided larvicidal activity with $LC_{50}$: 80.21 ppm and $LC_{90}$: 210.18 ppm, and repellent activity with $IC_{50}$: 0.82% and $IC_{90}$: 4.88%. The present study showed the effectiveness of E. urophylla as natural insecticide against C. quinquefasciatus, the mosquito vector of filariasis.

• BMB Reports
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• v.37 no.3
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• pp.292-297
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• 2004

The current model for the mechanism of action of the Bacillus thuringiensis Cry $\delta$-endotoxins involves the penetration of the ${\alpha}4-{\alpha}5$ hairpin into the target midgut epithelial cell membranes, followed by pore formation. In this study, PCR-based mutagenesis was employed to identify a critical residue within the ${\alpha}4-{\alpha}5$ loop of the 130-kDa Cry4A mosquito-larvicidal protein. Alanine-substitutions of two charged (Asp-198 and Asp-200) and four polar (Asn-190, Asn-195, Tyr-201 and Tyr-202) residues in the ${\alpha}4-{\alpha}5$ loop were performed. Like the wild-type, all of the mutant toxins were over-expressed as inclusion bodies in Escherichia coli. When E. coli cells expressing each mutant toxin were bioassayed against Aedes aegypti larvae, larvicidal activity was completely abolished for the substitution of only Tyr-202, while replacements at the other positions still retained a high level of toxicity. Further replacement of Tyr-202 with an aromatic side chain, phenylalanine, did not affect the toxicity. These results revealed a crucial role in toxin activity for the conserved aromatic residue at the 202 position within the ${\alpha}4-{\alpha}5$ loop of the Cry4A toxin.

• The Korean Journal of Pesticide Science
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• v.10 no.1
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• pp.43-49
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• 2006

Larvicidal activity of 34 plant essential oils were tested against the 4th instar larvae of Culex pipiens pallens. Among them, six oils (basil, fennel, caraway seed, lime, thyme red, and thyme white) showed more than 80% mortality at 100 mg $litre^{-1}$ concentration. GC and GC-MS analyses of the six essential oils and bioassay of their components revealed that anethole (a major component of fennel and basil oil) and (+)-limonene (a major component of caraway seed and lime oil) showed higher larvicidal activities than others. In addition to the above two components, ${\alpha}$-phellandrene, p-cymene, $\gamma$-terpinene, ${\beta}$-pinene, and thymol showed higher larvicidal activity than Bt product.