• Korean journal of applied entomology
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• v.48 no.1
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• pp.101-108
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• 2009

For biological control of larva of Cnaphalocrocis medinalis and Naranga aenescens do considerable damage to crops by folding and scraping the leaf tissue of rice, a large number of Bacillus thuringiensis isolates have been obtained from soil samples in Korea and the pesticidal activity was assayed against two insect pest species described above. Among 53 Bt isolates tested in bioassay, 18 and 13 isolates showed over 90% mortality against C. medinalis and N. aenescens, respectively. Some isolates (11 isolates including CAB141) presented dual activity against C. medinalis and N. aenescens. These isolates showed over 96% control effect in pest control in laboratory against larvae of C. medinalis. Also, it was investigated that pupation, pupal length, and adult emergence of larvae exposed to Bt suspension decreased. Especially, the pupal length of C. medinalis after being fed corn seedling leaves treated Bt suspension for 10 days, were much smaller than that of control.

• Journal of Microbiology and Biotechnology
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• v.13 no.1
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• pp.50-56
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• 2003

A freshwater bloom-forming cyanobacterium, Microcystis aeruginosa, and local soil isolate Scytonema sp. strain BT 23 were demonstrated to contain biotoxic secondary metabolites with pesticidal and mosquito larvicidal activities. A purified toxic constituent from M aeruginosa showed an absorption maximum at 230 nm and its toxicity symptoms, Rf value on TLC, and retention time observed ill an HPLC analysis were similar to those of the hepatotoxic heptapeptide microcystin-LR. The bioactive constituent of the Scytonema sp. was less polar in nature and exhibited two peaks at 240 and 285 m. When applied to two cruciffrous pests, Pieris brassicae and Plutella flostella, the crude extracts and toxic principles from the two cyanobacteria showed significant antifeedant activity in a no-choice bioassay, and at higher concenuations exhibited contact toxicity to the insect larvae. The purified toxin from M. aeruginosa was found to be more effective and produced 97.5 and $92.8\%$ larval mortality in the two pests, fo11owing 2 h of toxin treatment at a concentration of $25{\mu}g$ Per leaf disc (2.5 cm dia.). Meanwhile, similar treatment with the purified toxin from Sytonema sp. stain BT 23 only produced 73 and $78\%$ mortality in the two pests. The cyanobacterial constituents also showed significant activity against Culex and Anopheles larvae. The M. aeruginosa toxin ($20{\mu}g\;ml^-1$) caused 98.2 and $88.1\%$ mortality in the Culex and Anopheles larvae, respectively, while the purified toxin from the Sytonema sp. was less toxic and only produced a 96.3 and $91.2\%$ mortality, respectively, at a much higher concentration ($40{\mu}g\;ml^-1$). Accordingly, the current results point to certain hitherto unknown biological properties of cyanobacterial biotoxins.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.287-290
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• 2011

Environment friendly agricultural material products (EFAMs) in current market were evaluated for their insecticidal or acaricidal activities. EFAMs were evaluated against Tetranychus urticae, Plutella xylostella, Myzus persicae and Nilaparvata lugens in spray method. Several EFAMs indicated high control value in spray method. Hatchability of T. urticae was relatively high after EFAM treatment. some materials show high insecticidal activities against P. xylostella larvae but not against eggs. Few mete rials showed more than 80% insecticidal activities against M. persicae and N. lugen. The control value of more than half the materials for pest control was lower than 60%. EFAMs containing S. flavescens, neem oil and Rape showed higher control value.

• The Korean Journal of Pesticide Science
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• v.2 no.1
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• pp.24-31
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• 1998

Chemical derivative synthesis of ricinine, an active compound of Ricinus communis which showed high mortality against brown planthopper (Nilaparvata lugens), was performed to improve its pesticidal activity and the toxicity of 12 synthetic derivatives against major insect pests and phytopathogenic fungi were examined. Carbamate derivatives of ricinine could be synthesized from the precursor of ricinine, chloronorricinine and norricinine, whereas the derivatives were not synthesized from chlororicinic acid and ricinic acid having ketone group of pyridine ring. In organophosphates, reaction with oxon type of phosphate gave better yield than thiono type. Among the organophosphate derivatives of ricinine, thiono type of derivative structure gave $96.3%{\sim}100%$ mortality of the brown planthopper and the two-spotted spider mite (Tetranychus urticae) at 500 ${\mu}g/ml$ level. On the other hand, carbamate derivatives did not show insecticidal activity. In the fungicidal activity of ricinine derivatives, the derivative having amino radical at the 2 position of ricinine gave 85 to 100% of mycelium growth inhibition effect against ten major plant pathogens at the 200 ${\mu}g/ml$ level. In particular, the control value of the derivative on the rice blast (Pyricularia grisea) and barley powdery mildew (Erysiphe graminis) at the 250 ${\mu}g/ml$ level in vivo under greenhouse conditions was 92% and 96%, respectively.

• Korean Journal of Environmental Biology
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• v.22 no.4
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• pp.487-493
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• 2004

To investigate the antifungal activity related protein in pesticidal bacteria, a bacterial strain LTD was isolated from soil collected at Gimje in Jeonbuk province, Korea, and identified as Bacillus subtilis LTD based on a API50 CHB kit and 168 rDNA sequencing. It has an antifungal activity against 9 plant pathogenic fungi in a paper disc assay. The antifungal activity- deficient mutant, B. subtilis mLTD was induced at a 5 kGy dose of $^{60}Co$ gamma radiation. Using the two-dimensional electrophoresis and the matrix assisted laser desorption ionization time-of-flight mass spectrometry, the comparison analysis of proteins between the wild and mutant were performed. A major intracellular serine proteinase IspA (MW: 32.5 kDa), a NAD (P) H dehydrogenase (MW: 20.0 kDa), and a stage II sporulation protein AA, SpoIIAA (MW: 14.3kDa) were detected only in the B. subtilis LTD. These results suggested that the functions of these proteins found only in the B. subtilis LTD could. be closely related to the antifungal activity against plant pathogenic fungi.

• The Journal of the Korea Contents Association
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• v.9 no.2
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• pp.339-349
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• 2009

Garlic (Allium sativum, L.) has a long history of reputed value and actual use for its medicinal, antimicrobial, and pesticidal properties. This study was conducted to find possible developments to natural food preservatives from garlic extracts. Garlic extracts were prepared from fresh crushed garlic and diluted with sterilize distilled water. The sensitivity test was conducted to investigate the antimicrobial effect of garlic extract against six strains of food poisoning bacteria such as Staphylococcus aureus, Escherichea coli, Salmonella typhimurium, Vibrio parahemolyticus, Bacillus subtilis, and Listeria monocytogenes. The results of sensitivity test were then compared with those of Vancomycin and Imipenem which were used as treatment for G. (+) bacteria and G. (-) bacteria, respectively. All of the 6 tested strains exhibited strong or moderate activity. V. parahemolyticus exhibited susceptible only in undiluted solution, but not in diluted garlic extracts.

• Journal of Applied Biological Chemistry
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• v.48 no.2
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• pp.65-74
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• 2005

Fungicidal, insecticidal, and mosquito larvicidal activities of piperidine alkaloids, pipernonaline and piperoctadecalidine, and isobutylamide alkaloids, pellitorine, guineensine, pipercide, and retrofractaminde A, derived from Piperaceae fruits were studied. Pipernonaline and piperoctadecalidine showed potent fungicidal activities against Puccinia recondita with 91 and 80% control values at 500 ppm. Against Phytophthora infestans, pipernonaline showed strong fungicidal activity with 91 and 80% control values at 1,000 and 500 ppm. $LD_{50}$ values of pipernonaline and piperoctadecalidine against Plutella xylostella were 125 and 95.5 ppm, respectively, and that of piperoctadecalidine against Tetranychus urticae was 246 ppm. Against larvae of Aedes aegypti and Culex pipiens pallens, $LD_{50}$ values of pipernonaline were 0.35 and 0.21 ppm, respectively. Highest larvicidal activities of pipercide and retrofractamide A were found against A. aegypti, A. togoi, and C. pipiens pallens. $LD_{50}$ values of pipercide and retrofractamide A were 0.10 and 0.039 ppm against A. aegypti, 0.26 and 0.01 ppm against A. togoi, and 0.004 and 0.028 ppm against C. pipiens pallens, respectively. Based upon these results and earlier findings, bioactive components derived from Piperaceae fruits may be valuable for development of useful lead product of possibly safer fungicidal, insecticidal, and mosquito larvicidal agents.

• Applied Biological Chemistry
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• v.48 no.2
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• pp.150-154
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• 2005

To overcome the problems associated with chemical pesticides, biological pest controls agent extracted from Ginkgo biloba was studied. Insecticidal activities components in Ginkgo biloba extracts were analyzed using high performance liquid chromatography (HPLC). This results of HPLC analysis, GG-W80 were included bilobalide $611\;{\mu}g/kg$, ginkgolide A $37\;{\mu}g/kg$ and ginkgolide B $243\;{\mu}g/kg$, while YG-W80 were included bilobalide $214\;{\mu}g/kg$ and ginkgolide B $46\;{\mu}g/kg$. The biological activity of Ginkgo biloba extracts were conducted to repellent and pesticidial effect of Tetranichus urticae, Aphis gossypii and Myzus persicae treated with Ginkgo biloba leaves extracts. Mortalities of adult T. urticae to green Ginkgo biloba extracts (GG-W80) and yellow Ginkgo biloba extracts (YG-W80) were shown 98.3% and 20.0%, respectively. From these results, terpenes components in Ginkgo biloba extracts could be use for biological controls for T. urticae.

• Korean Journal of Environmental Agriculture
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• v.16 no.4
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• pp.347-355
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• 1997

For the selection of plants contained pesticidal active conpounds, 31 families 59 species of native plants were collected and biological activites of their crude extracts against brown planthopper (Nilaparvata lugens), Xanthomonas oryzae pv. oryzae and allelopathy were examined. Among the screened plants, the crude extracts from the leaves of Ricinus communis and Sophora angustifolia showed 100% and 82% of mortality on brown planthopper at the concentration of 1% (w/v) respectively. Mixed crude extracts of Sophora angustifolia root and Melia azedarach seed exhibited 128${\sim}$155% of synergistic effects on the mortality of brown planthopper. In case of fungicidal activity, the crude extracts from the leaves of 8 plants including Chrysanthemum indicum were inhibitory of the growth of Xanthomonas oryzae pv. oryzae at 1%(w/v) soluction. Seed germination of radish (Raphanus sativas) and barnyardgrass (Echinochloa crus-galli) was inhibited by 0.5%(w/v) leaf extracts of Pinus densiflora and Quercus acutissima. MeOH extracts of Pinus denislora leaves gave 100% inhibition in seed germintion of radish at 2%(w/v) soluction and showed a complete inhibition in seedling growth of barnyardgrass as well as radish at 5% solution.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.381-387
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• 2014

BACKGROUND: Garlic (Allium sativum) extract has been allowed as commercial biopesticide material for pesticidal activity in the Environmentally-friendly Agriculture Promotion Act. Nine commercial biopesticides containing A. sativum extract have been marketed in Korea. However, the analytical method of the active substances in these materials has not been studied. METHODS AND RESULTS: Cartridge clean-up method for the determination of dimethyl disulfide(DMDS), diallyl disulfide(DADS), and diallyl trisulfide(DATS) in biopesticides containing A. sativum extract was developed and validated by gas chromatography(GC). The clean-up method was optimized using hydrophilic lipophilic balance (HLB) solid phase extraction(SPE) cartridges for the bioactive sulfides in biopesticides containing A. sativum extract, and the eluate was analyzed to quantify the DMDS, DADS, and DATS using the GC. The developed method was validated, and the LOQ and recovery rates of DMDS, DADS, and DATS were 0.226, 0.063, and $0.051mg\;L^{-1}$ and 80.6, 84.8, and 73.1%, respectively. From the nine commercial biopesticide samples, contents of DMDS, DADS, and DATS were analyzed using the developed method and results showed $2.3mg\;L^{-1}$, respectively. CONCLUSION: The developed method could be used in determining the quality of biopesticides for the manufacture of commercial biopesticides containing A. sativum extract.