• Research in Plant Disease
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• v.9 no.2
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• pp.99-103
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• 2003

Bioactivities of Korean ginkgo (Ginkgo biloba L.) extract were investigated against several fungi, general bacteria and insect pests. Crude methanolic extracts of different parts of Korean ginkgo showed different bioactivities depending on the target organisms. The methanolic extract showed in vitro antimicrobial activity at dose of 200 ug per paper disc. The extract of ginkgo stalk was some higher than seed coat and root. The extract also showed a remarkable in vivo antifungal activity against green mold (Trichoderma harzianum) on compost surface of spawn bags and in vivo insecticidal activity to Nilaparvata lugens, Plutella xylostella and Tetranychus urticae. This study suggests that Korean ginkgo extracts have a potential as a natural pesticide.

• Microbiology and Biotechnology Letters
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• v.26 no.4
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• pp.358-364
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• 1998

New microbial-control agents were prepared with B. thuringiensis strain NT0423 having unique properties which are different with other B. thuringiensis strains belonging to serotype 7[Kor. J. Appl. Entomol. 32: 426-432.]. Three B. thuringiensis formulations designated as BioBact 10%, 20% and 40%, were made with various combinations of adjuvants. These formulations showed good physical properties in wettability, suspensibility, particle size and adherence. In addition the result of SDS-PAGE analysis indicated that $\delta$-endotoxins remain stably in all formulations. Among the tested formulations, two wettable powder formulations, BioBact 20% and 40%, comprising 20% and 40% of B. thuringiensis technical powder showed the effective control against diamondback moth larvae (Plutella xylostella) in laboratory and field tests. Especially, when compared with commercial B. thuringiensis formulations (A and B commercial formulations) in field evaluation, BioBact 20% and 40% formulations showed equal activity up to 80% lethality and a good persistence effect which remain on leaves at least 7 days.

• The Korean Journal of Pesticide Science
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• v.8 no.4
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• pp.258-264
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• 2004

The pyrazole family was discovered as effective insecticides/acaricides, and fenpyroximate and tebufenpyrad were introduced in the market. In this study, new series of pyrazole oxime ethers were designed and synthesized. The pyrazolone 1 was prepared by the condensation of ethyl acetoacetate with methylhydrazine, and then subsequently subjected to the Vilsmeier-Haack chloroformylation yielding 4-formyl-5-chloro-pyrazole 2. The nucleophilic aromatic substitution of 2 generally allowed the introduction of a wide range of heterocycles into the pyrazole ring. The resulting pyrazole aldehydes 3a-i were readily converted to the corresponding pyrazole oxime derivatives 4a-i, and subsequently to 5-substituted pyrazole oxime ether derivatives 6a-i. The screening assay results clearly show that the activities of 6d were comparable to those of fenpyroximate (6a) against BPH, DBM, and TSSM. It indicates that 6d has a potential to be developed as an insecticidal agent.

• Korean journal of applied entomology
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• v.31 no.2
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• pp.182-189
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• 1992

The influnces of 9 kinds of solvents on the toxicities against several insect species, phytotoxicity and solubility of compounds were evaluated by means of leaf dipping and spray methods. In case of the spray application, density and vapor pressure seemed to be a contributing factor to lethal toxicity against brown planthopper and diamond-back moth, respectively; the bigger the property of density and the smaller the vapor pressure gave the stronger toxicity. It appeared that the toxicity of solvents was not correlated with anyone of physical properties such as boiling point, dipole moment, dielectric constant, surface tension and viscosity. Spray treatment gave more toxicity to insects than leaf dipping treatment. Although dielectric constant and dipole moment seemed to be contributing factors to phytotoxic damage to rice seedling and bean plants, respectively, no general correlation between phytoxicity and the other physical properties was found. Leaf dipping application caused stronger phytotoxicity than spray application. It is concluded that 5% acetone solution may be most suitable to test chemicals because of its favorable solubility of compounds, lower toxicity to insects, and lower phytotoxicity.

• Korean journal of applied entomology
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• v.32 no.4
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• pp.426-432
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• 1993

Thirteen isolates of Bacillus thunngiensls producing parasporal mclusions, obtained from 45 samples of dust and soil of sericultural tarms in Kyeong-ki province, were exammed for their toxicity against larvae of Lepidoptera, Dipwra and Coleoptera. Of these isolates, Bacillus f thuringiensis NT0423 was toxic to bath Lepidoptera, and Dipteran larvae. NT0423 showed that the $LC_{50}$ values against the Lepldaptora, Plutella macuhpennis and the Diptera, Culex pipiens were $1.30\times10^6$ CFU/ml, $2.88\times10^5$ CFU/ml, respectively. The tYPlcal bipyramldal crystals produced by NT0423 composed of protoxms of 130-140kDa encoded by one or more plasm mid-horne genes. Also, plasmid DNA analysis indicated Lhat this isolate has 9 plasmids which d differ with reported several B. thuringiensis strains.

• Korean Journal of Environmental Agriculture
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• v.40 no.1
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• pp.1-12
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• 2021

BACKGROUND: G protein-coupled receptors (GPCRs) are widely distributed in various organisms. Insect GPCRs shown as in vertebrate GPCRs are membrane receptors that coordinate or involve in various physiological processes such as learning/memory, development, locomotion, circadian rhythm, reproduction, etc. This study aimed to identify GPCRs expressed in fat body and compare the expression pattern of GPCRs in different temperature conditions. METHODS AND RESULTS: To identify GPCRs genes and compare their expression in different temperature conditions, total RNAs of fat body in Plutella xylostella larva were extracted and the transcriptomes have been analyzed via next generation sequencing method. From the fat body transcriptomes, genes that belong to GPCR Family A, B, and F were identified such as opsin, gonadotropin-releasing hormone receptor, neuropeptide F (NPF) receptor, muthuselah (Mth), diuretic hormone receptor, frizzled, etc. Under low temperature, expressions of GPCRs such as C-C chemokine receptor (CCR), opsin, prolactin-releasing peptide receptor, substance K receptor, Mth-like receptor, diuretic hormone receptor, frizzled and stan were higher than those at 25℃. They are involved in immunity, feeding, movement, odorant recognition, diuresis, and development. In contrast to the control (25℃), at high temperature GPCRs including CCR, gonadotropin-releasing hormone receptor, moody, NPF receptor, neuropeptide B1 receptor, frizzled and stan revealed higher expression whose biological functions are related to immunity, blood-brain barrier formation, feeding, learning, and reproduction. CONCLUSION: Transcriptome of fat body can provide understanding the pools of GPCRs. Identifications of fat body GPCRs may contribute to develop new targets for the control of insect pests.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.343-349
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• 2013

Environment-friendly agro-materials tend to be preferred to chemical insecticides recently. For this reason, many studies are conducted to develop environment-friendly insecticides containing natural materials. The purpose of this study was to assess ecotoxicity for pepper extract and cassia oil (11.5+46%, A), pepper extract and cassia oil (23+34%, B), and pepper extract and lavender oil (40+10%, C). They are expected to prevent from pests especially diamondback moth, and can be used for agro-materials. Their formulation was emusifiable concentration (EC). Target species used to assess acute toxicity were aquatic invertebrate (Daphina magna), fish (Cyprinus carpio), honeybee (Apis mellifera L.) and earthworm (Eisenia fetida). The $EC_{50}$ value of A, B, and C to aquatic invertebrate were 0.46, 1.9, 0.25 mg $L^{-1}$ respectively and these values were moderately toxic according to standard of USEPA. In case of acute toxicity test to fish, the $LC_{50}$ of A, B, and C were 1.9, 2.9, 3.8 mg $L^{-1}$ respectively. A was category II in acute toxicity of fish and not acceptable to evaluation criteria of environment-friendly agro-materials. B and C were category III and acceptable. Acute contact and oral toxicity test to honeybee were conducted and the $LD_{50}$ of A, B, and C were > 100 ${\mu}g$ a.i. $bee^{-1}$ in both of tests. It indicated they were low toxic to honeybee. In case of acute toxicity test to earthworm, $LC_{50}$ of A, B, and C were 695, 988, and 564 mg $kg^{-1}$. In conclusion, pepper extract+cassia oil 57% EC and pepper extract+lavender oil 50% EC were expected to be used for environment-friendly insecticide materials with low risk against ecosystem and contribute to developing environment-friendly agro-materials.

• The Korean Journal of Pesticide Science
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• v.8 no.4
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• pp.338-346
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• 2004

The methanol extract of Chloranthus japonicus roots effectively controlled the development of rice blast(Magnaporthe grisea), rice sheath blight(Corticium sasaki), tomato pay mold(Btrytis cinerea), tomato late blight(Phytophthora infestans), and wheat leaf rust(Puccinia recondita). From the methanol extract of C. japonicus roots, three antifungal substances were isolated. Their chemical structures were determined to be shizukanols B, C, and D mainly by mass and NMR spectral data. Among the three substances, shizukanol C showed the strongest inhibitory activity against mycelial growth of the plant pathogenic fungi tested; it completely inhibited mycelial growth of M. grisea. Colletotrichum gloeosporioides, and C. acutatum at concentrations of more than $12.5{\mu}g$/ and P. infestans at concentrations of more than $3.13{\mu}g/m\ell$. They also controlled effectively the development of rice blast and wheat leaf rust. On the other hand, they caused phytotoxic symptoms on barley leaves and inhibited the growth of duckweed (Lemna paucicostata) with $EC_{50}$ values of $30.0{\mu}g/m\ell$ for shizukanol B, $49.9{\mu}g/m\ell$ for shizukanol C, and $154{\mu}g/m\ell$ for shizukanol D. In addition, shizukanol C showed an insecticidal activity against brown planthopper (Nilaparavata lugens), peen peach aphid (Myzus persicae), diamond-back moth (Plutella xylostella), and tobacco cutworm (Spodoptera litura) of the 5 arthropod pests tested with mortality values of more than 60% at a concentration of $1,000{\mu}g/m\ell$.

• Korean journal of applied entomology
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• v.51 no.1
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• pp.47-58
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• 2012

Effect of a new crop protectant 'Bt-Plus' on natural enemies was analyzed in this study. Tested natural enemies included two parasitic species of $Aphidius$ $colemani$ and $Eretmocerus$ $eremicus$, and four predatory species of $Harmonia$ $axyridis$, $Orius$ $laevigatus$, $Amblyseius$ $swirskii$, and $Phytoseiulus$ $persimilis$. 'Bt-Plus' was formulated by combination of three entomopathogenic bacteria ($Xenorhabdus$ $nematophila$ (Xn), $Photorhabdus$ $temperata$ subsp. $temperata$ (Ptt), $Bacillus$ $thuringiensis$ (Bt)) and bacterial metabolite (BM). All three types of 'Bt-Plus' showed significantly higher toxicities against fourth instar $Plutella$ $xylostella$ larvae than Bt single treatment. Two types of bacterial mixtures ('Xn+Bt' and 'Ptt+Bt') showed little toxicity to all natural enemies in both contact and oral feeding assays. However, 'BM+Bt' showed significant toxicities especially to two predatory mites of $A.$ $swirskii$ and $P.$ $persimilis$. The acaricidal effects of different bacterial metabolites were evaluated against two spotted spider mite, $Tetranychus$ $urticae$. All six BM chemicals showed significant acaricidal effects. The BM mixture used to prepare 'Bt-Plus' showed a high acaricidal activity with a median lethal concentration at 218.7 ppm (95% confidence interval: 163.2 - 262.3). These toxic effects of bacterial metabolites were also proved by cytotoxicity test against Sf9 cells. Especially, benzylideneacetone, which was used as a main ingredient of 'BM+Bt', showed high cytotoxicity at its low micromolar concentration.

• The Korean Journal of Pesticide Science
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• v.4 no.3
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• pp.19-26
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• 2000

In order to select potent bioactive isolates, 70 Fusarium isolates obtained from soil and 21 plant species were screened by antifungal, insecticidal, herbicidal, and duckweed bioassays after culturing in potato dextrose broth and rice solid media. Eight (11.4%) of the 70 liquid broth cultures showed disease-controlling activities more than 80% against at least one of the 6 plant diseases tested. Fusarium sp. FO-68 isolate exhibited the most potent antifungal activity; it controlled rice blast, wheat leaf rust, and barley powdery mildew with control values more than 95%. Out of 70 solid cultures, 21 (30.0%) controlled at least one plant disease more than 80% and F. equiseti FO-68 isolate showed disease-controlling activities more than 95% against 3 plant diseases such as rice blast, tomato late blight, and wheat leaf rust. As for tile insecticidal activities, 2 liquid and 1 solid cultures showed potent insecticidal activities against pest insects more than 80%, Liquid cultures of F. oxysporum FO-61 and Fusarium sp. FO-80 isolates exhibited insecticidal activities more than 80% against green peach aphid and diamondback moth, respectively. The solid culture of Fusarium sp. FO-510 isolate had 80% insecticidal activity against green peach aphid. However, none of liquid and solid cultures of the 70 Fusarium isolates showed potent herbicidal activities against 10 upland weeds. As the results of duckweed assay, 3 liquid cultures showed 70% growth inhibitory activity at concentrations less than 1.25% of culture supernatants and 9 solid cultures had a potent inhibitory activity against duckweed growth. On the other hand, there was a significant correlation between antifungal activities and herbicidal activities against duckweed of both liquid and solid cultures of tile 70 Fusarium isolates.