• Korean journal of applied entomology
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• v.49 no.4
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• pp.417-422
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• 2010

Cultural characteristics Lecanicillium lecani Btab01 and its insecticidal activity against tobacco whitefly (Bemisia tabaci) were investigated. On potato dextrose agar, tryptic soy agar and SDA+Y media, mycelial growth of L. lecani Btab01 was best at $20{\sim}25^{\circ}C$ and suppressed above $28^{\circ}C$. Both solid culture and liquid culture of L. lecani Btab01 showed high insecticidal activity, 93.9 and 98.3% respectively, against nymph of tobacco whitefly, but there is no significant difference. When culture of L. lecani Btab01 was treated at the concentration of $10^5$, $10^6$, $10^7$ and $10^8$ cfu/ml, their insecticidal activity were 5.8%, 33.8%, 77.3% and 98.5% respectively, and $LT_{50}$ values were 16.1 days, 7.3 days, 5.1 days and 3.5 days respectively. When nymphs were treated by the cultures of L. lecani Btab01 and maintained under saturated condition for zero hour, 24 hours and 168 hours, their control activities were 0%, 20.3% and 100% respectively. Spore germination of L. lecani Btab01 was increased about two times by adding edible oil. When L. lecani Btab01 was treated to control nymph with 0.1% edible oil, it showed high control activity(98.6%) compared to single treatment of L. lecani Btab01 (79.9%).

• Journal of Microbiology
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• v.42 no.4
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• pp.340-345
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• 2004

To investigate the co-expression and crystallization of a fusion gene between the Bacillus thuringiensis crystal protein and a foreign protein in B. thuringiensis, the expression of the Cry1Ac fused with green fluorescent protein (GFP) genes in a B. thuringiensis $Cry^-B$ strain was examined. The cry1Ac gene was cloned in the B. thuringiensis-E. coli shuttle vector, pHT3101, under the control of the native cry1Ac gene promoter, while the GFP gene was inserted into the XhoI site upstream of the proteolytic cleavage site, in the middle region of the crylAc gene (pProAc-GFP). The B. thuringiensis $Cry^-B$ strain carrying pProAc-GFP (ProAc-GFP/CB) did not produce any inclusion bodies. However, the transformed strain expressed fusion protein forms although the expression level was relatively low. Furthermore, an immu­noblot analysis using GFP and Cry1Ac antibodies showed that the fusion protein was not a single spe­cies, but rather multiple forms. In addition, the N-terminal fragment of Cry1Ac and a non-fused GFP were also found in the B. thuringiensis $Cry^-B$ strain after autolysis. The sporulated cells before autolysis and the spore-crystal mixture after autolysis of ProAc-GFP/CB exhibited insecticidal activities against Plutella xylostella larvae. Accordingly, the current results suggest that a fusion crystal protein produced by the transfomant, ProAc-GFP/CB, can be functionally expressed but easily degraded in B. thuring­iensis.

• Korean journal of applied entomology
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• v.54 no.2
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• pp.55-62
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• 2015

'Bt-Plus' has been developed by mixing spores of Bacillus thuringiensis (Bt) and culture broth of Xenorhabdus nematophila (Xn). Despite its high toxicity, it has some imitation to broaden its efficacy against diverse insect pest spectrum. This study focuses on enhancement of Bt-Plus toxicity against semi-susceptible insect, Spodoptera exitgua, by addition of Xn metabolites. Two main Xn metabolites, oxindole (OI) and benzylideneacetone (BZA), are known to enhance the Bt insecticidal activities. The addition of OI or BZA significantly increased Bt-Plus pathogenicity. However, when the freeze-dried Xn culture broth was added to Bt-Plus, much less amount was enough to enhance the toxicity compared to the amount of OI or BZA. An HPLC analysis indicated that there were more than 12 unidentifed bacterial metabolites in Xn culture broth. These suggest that there are potent biological response modifiers in Xn metabolites other than OI and BZA.

• Korean journal of applied entomology
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• v.33 no.2
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• pp.81-87
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• 1994

The experiments were canied out to investigate the toxicological characteristics of Insect Growth Regulators (IGRs) such as chlorfluazuron, diflubenzuron, pyriproxyfen and tebufenozide against the various stages of instars of fall webwom (Hyphantrio cuneo Dmy) and nce stem borer (Chiio suppressaiis Walker). In fall webwom, the tolerance ratio m) with the 2nd-6th instars, as cornpared with LCso of the 1st instar, ranged 107-358, 1.13-6.06, 1.02-3.23 and 1.05- 6.64, respectively. In the rice stern borer, the TR of the 3rd instar, as compared with LCso of the 1st instar, to chlorfluazuron, diflubenzuron, pyriproxyfen and tebufenoz~de were 2.86, 260, 19.80 and 15.30, respectively.

• Korean Journal of Pharmacognosy
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• v.35 no.2 s.137
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• pp.164-170
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• 2004

The flavonoids are a very large and important group of polyphenolic natural products, which are united by their derivatization from the heterocycle, flavone. They are distributed in higher plants and occur widely in the fruits and vegetables that make up the human diet. They exhibit a wide range of biological properties, including antitumor, antiinflammatory, hepatoprotective, antimicrobial, insecticidal and estrogenic activities. They are also major components of many plant drugs and it is possible that they contribute to the curative properties. For the purpose of developing anticancer agent of natural origin, we have evaluated forty four kinds of naturally occurring flavonoids for the inhibitory activity upon the proliferation of cultured human tumor cells such as A549 (non small cell lung), SK-OV-3 (ovary), SK-MEL-2 (melanoma), XF498 (central nerve system) and HCT-15 (colon) in vitro.

• Korean journal of applied entomology
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• v.49 no.3
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• pp.251-259
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• 2010

A bacterial colony was isolated from the gut of the bean bug, Riptortus clavatus. From morphological and biochemical tests, the bacterial isolate showed the highest similarity to Staphylococcus succinus. DNA sequence of 16S rRNA gene of the bacterium supported the identification. Oral administration of penicillin G to adults of R. clavatus gave a dose-dependent mortality of adults of R. clavatus to adults along with significant decrease of the bacterial population in the gut. Similarly, three metabolites (benzylideneacetone, proline-tyrosine, and acetylated phenylalanine-glycine-valine) derived from an entomopathogenic bacterium, Xenorhabdus nematophila, also inhibited growth of the gut bacterial population and gave significant mortalities to R. clavatus. These results suggest that a gut bacterial population classified as Staphylococcus sp. is required for survival of R. clavatus and that the three bacterial metabolites had toxic effects on the bugs due to their antibacterial properties.

• The Korean Journal of Pesticide Science
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• v.6 no.2
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• pp.80-86
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• 2002

The activities against Frankliniella occidentalis adults collected at rose greenhouse of 40 commerical insecticides were investigated. Among them 9 insecticides showed over 80% mortality to the adults; chlorfenapyr, chlorpyrifos- methyl, emamectin benzoate, fenthion, fipronil, phenthoate, spinosad, chlorpyrifos+diflubenzuron and furathiocarb+diflubenzuron. Susceptibility of field populations collected from greenhouse rose at 5 locations in 2001 was evaluated against the 9 insecticides selected. There was considerable difference in susceptibility depending on the treated insecticides and the regions from which the populations were collected. Goyang and Gimhae populations showed lower $LC_{50}$(ppm) values then Imsil, Jincheon and Gaangjin populations to all the tested insecticides. The adults of all field populations showed lower $LC_{50}$ values less than 1 ppm to emamectin benzoate, fipronil and spinosad. From these results, we could recommend 5 insecticides, such as emamectin benzoate, fipronil, spinosad, chlorpyrifos+diflubenzuron and furathiocarb+diflubenzuron as effective ones to control the Frankliniella occidentalis field populations.

• 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.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.325-329
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• 2012

In this study, 1, 2 and 4% aqueous extracts of common cocklebur (Xanthium strumarium) fruit were tested against pulse beetle (Callosobruchus chinensis) for development of an environmental friendly control methods of this pest. The common cocklebur fruit extracts showed effects on mortality, repellency, fecundity and adult emergence of C. chinensis and inhibited pulse grains from damage. The 4% extract showed the highest mortality (26%) and repellency rate (53.3%) at 2 day after treatment and 3 hours after treatment, respectively. The studied insects revealed lowest fecundity (113.7 female-1), highest percentage of adult emergence inhibition (37.0%) and lowest percentage (42.3%) of seed damage when they were reared on pulse grains mixed with 4% extract. This finding indicated that common cocklebur fruit extract may be used in the integrated management of pulse beetle for protecting stored grains.

• Korean Journal of Environmental Biology
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• v.34 no.3
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• pp.208-211
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• 2016

Essential oils (EOs) extracted from plants possess various biological activities and have been considered as natural insecticides due to their potent insecticidal activities. In regard to develop natural insecticides, EOs are formulated as an emulsifiable concentrate and their acute toxicity against to fishes were determined in a static condition using Cyprinus carpio. Coriander EO was used as an active ingredient mixed with ethanol for solvent and various surface active agents. The tested EOs were obtained from a commercial market, and three different extractions were also undertaken to produce EO using steam distillation, solvent extraction, and supercritical fluid extraction. Among the emulsifiable concentrate including a commercial coriander EO, surface active agents such as Tween 80, sodium dodecyl benzene sulfonate (SDBS), and mixture of SDBS and Nonidet showed acute toxicity to the fish. With the three different EO extraction, coriander EO obtained from supercritical fluids with Triton X-100 exhibited acute toxicity to C. carpio. Taken together, Tetgitol and Nondet are considered as surface active agents for the emulsifiable formulation of coriander EO.