• Korean journal of applied entomology
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• v.47 no.4
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• pp.457-465
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• 2008

Eight Bacillus thuringiensis strains activated against mosquito larva were compared their characterization. Spherical-shaped parasporal inclusion of B. thuringiensis subsp. tohokuensis CAB167 was observed by phase-contrast microscopy and scanning electron microscopy. $LC_{50}$ values of B. thuringiensis subsp. tohokuensis CAB167 against Culex pipiens molestus, Culex pipiens pallens, and Aedes aegyti were 173, 190 and 580 ng/ml, respectively. B. thuringiensis subsp. tohokuensis CAB167 had a parasporal inclusion containing 4 major protein components, for example, 135, 80, 49 and 28-kDa by SDS-PAGE. Otherwise, after trypsin digestion of parasporal inclusion, SDS-PAGE was showed new protease-resistant peptides at 72 and 63-kDa. Activated toxins of isolated CAB167 were different from other reference strains on a serological by immuno-diffusion test.

• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.446-455
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• 2010

The characteristics of parasporal inclusion body from Bacillus thuringiensis subsp. kurstaki KB099 isolate which is high bioactive to the tobacco cutworm, Spodoptera litura, were examined. Parasporal inclusion of B. thuringiensis subsp. kurstaki KB099 isolate showed only 1 band at 130 kDa compared with B. thuringiensis subsp. kurstaki HD-l isolate producing 2 protein bands at 130 kDa and 60 kDa from by SDS-PAGE analysis without any enzyme treatment. Also, we confirmed that gut extract of sensitive S. litura KB099 isolate had digested only 60 kDa ${\delta}$-endotoxin protein. When the digestive enzyme of sensitive insect responsible for parasporal inclusion from KB099 and HD-l isolate was treated to each of them, protein band 60 KDa of KB099 was maintained up to 12 hours but all bands of HD-l were disappeared within 6 hours. In KB099 isolate, 6 genes (Cry1Aa, Cry1Ab, Cry1Ac, Cry1C, Cry1D and Cry1I) were identified by PCR analysis. Also, $Cry^-$ mutant of KB099 isolate was investigated by phase- contrast microscope, SDS-PAGE and PCR.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.363-370
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• 2013

Susceptibility of each developmental stage of Phthorimaea operculella (Lepidoptera: Gelechiidae) were investigated using 16 insecticides which are available in the market in Korea. For the eggs and pupae, only spinosad showed a 71.1% inhibition rate for egg hatchability and a 66.7% inhibition rate for emergence. For the 3rd instar larvae, the feeding toxicities were over 90% for fenitrothion ($LC_{50}$ 336.6 ppm), esfenvalerate ($LC_{50}$ 8.6 ppm), ethofenprox ($LC_{50}$ 35.7 ppm), and emamectin benzoate ($LC_{50}$ 0.05 ppm). Furthermore, the contact toxicities were over 90% for esfenvalerate ($LC_{50}$ 0.87 ppm), ethofenprox ($LC_{50}$ 16.5 ppm), emamectin benzoate ($LC_{50}$ 0.53 ppm), and spinosad ($LC_{50}$ 2.48 ppm) at the recommended concentrations. Deltamethrin and spinosad yielded 100% mortality for adult P. operculella 48 h after treatment. The adult female fecundity was inhibited by deltamethrin, esfenvalerate, emamectin benzoate, spinosad and dinotefuran, which were significantly different from the control. The adult longevities (7.3-8.3 days) were reduced by approximately 1-2 days compared with the control (9.3 day). The emamectin benzoate maintained 100% insecticidal activity 14 days after treatment and ethofenprox maintained over 90% activity 7 days after treatment.

• Korean journal of applied entomology
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• v.48 no.4
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• pp.493-501
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• 2009

To investigate resistance of Myzus persicae, which is resistant to etofenprox belonging to pyrethriods, to other insecticides, fenpropathrin and thiamethoxam, mortality and $LC_{50}$ values for these two insecticides against the etofenprox-resistant and -susceptible populations were obtained and EPG analysis for feeding behaviors of thiamethoxam or fenpropathrin treated and non-treated M. persicae was conducted. For fenpropathrin, mortality after 48 h treatment was 28 and 29%, respectively for the resistant and susceptible population. The $LC_{50}$ value was 193.15 and 93.46 ppm, respectively. For thiamethoxam, mortality after 48 h treatment was 87 and 57%, respectively for the resistant and susceptible population. The $LC_{50}$ value was 3.17 and 30.34 ppm, respectively. There was no significant difference in feeding behavior between fenprorpathrin treated and non-treated M. persicae. They showed a continuous feeding pattern. However, contact signal frequency increased in the thiamethoxam treated M. persicae 1 hour after treatment and significant difference was shown.

• Korean journal of applied entomology
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• v.56 no.2
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• pp.147-152
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• 2017

Heart contraction is essential for insect hemolymph circulation, in which various physiological changes need control of the heart contraction. Thus, interruption of heartbeats intimidate insect survival. Chlorine dioxide induces release of reactive oxygen species (ROS), which has been regarded as the main insecticidal agent. This study analyzed the effect of chlorine dioxide on heartbeats of the Indianmeal moth, Plodia interpunctella. The larvae have the dorsal vessel on the medial dorsal region in a form of an extending tube from the first thorax to 10th abdominal segment. Dorsal vessel contraction was noticeable between 3rd and 10th abdominal segments, where five heart chambers were observed. Average heartbeat rate was 118.6 beats per min at $25^{\circ}C$. However, the heartbeats varied with ambient temperature. Injection of chlorine dioxide to hemocoel suppressed the heartbeats in a dose-dependent manner. The suppressive effect of chlorine dioxide also increased with exposure time to gas form of the chemical at 100 ppm. However, vitamin E (an antioxidant against ROS) treatment significantly rescued the larvae treated with chlorine dioxide in the heart contraction activity. These results suggest that chlorine dioxide negatively influences on the heart contraction of P. interpunctella via its production of ROS.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.357-362
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• 2006

Bacillus thuringiensis strains were isolated from the domestic soil and a strain was selected that had a new host range and high toxicity against agriculture insect pest. The 142 samples of soil were sampled from the mountains, paddy fields and patches, in Daejon, Chungnam, Chungbuk and Jeonbuk and used for the investigation. Sixteen B. t strains were isolated from 12 samples among collected samples. There were 11 strains that showed toxical activity on Plutella xylostella (Lepidoptera: Yponomeutidae), 7 steins on Spodoptera litura (Lepidoptera: Noctuidae), 5 strains on Arete coerulea (Lepidoptera: Noctuidae), 5 strains on Culex pipiens pallens (Diptera: Culicidae) among the 16 isolated B. t strains. But there were not any strains that showed activity against Hyphanria cunea (Lepidoptera: Arctiidae) and Sitophilus oryzae (Coleoptera: Rhynchophoridae). And also some of B. thuringiensis strains showed insecticidal activity with 2, 3 or 4 kinds of insects. But there were also 3 strains that did not show any activities to the 6 insects which were used in the experiment. When examined with a phase-contrast microscope, the insecticidal crystal protein produced from 16 selected strains had 13 bipyramidal and 3 spherical shapes. The insecticidal bioactivity of the S. litura showed 100% mortality when there were $1.3{\times}10^{7}\;(cfu/ml)$ of CAB109 isolates.

• Korean journal of applied entomology
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• v.55 no.1
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• pp.27-33
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• 2016

Chlorine dioxide has been used as a disinfectant against microbial pathogens. Recently, its insecticidal activity has been known against stored insect pests by oxidative stress. However, any molecular target of the oxidative stress induced by chlorine dioxide has been not known in insects. This study assessed an enzyme activity of acetylcholinesterase (AChE) as a molecular target of chlorine dioxide in the Indianmeal moth, Plodia interpunctella. AChE activities were varied among developmental stages of P. interpunctella. Injection of chlorine dioxide with lethality-causing doses significantly increased AChE activity of the fifth instar larvae of P. interpunctella. Exposure of the larvae to chlorine dioxide fumigant also significantly increased AChE activity. The fifth instar larvae of P. interpunctella exhibited a negative phototaxis. However, chlorine dioxide treatment significantly interrupted the innate behavior. These results suggest that AChE is one of molecular targets of oxidative stress due to chlorine dioxide in P. interpunctella.

• Research in Plant Disease
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• v.15 no.3
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• pp.222-229
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• 2009

A Pseudomonas strain SG3 producing biosurfactant and showing antifungal and insecticidal activities was isolated from agricultural soil severely contaminated with machine oils. The antagonistic bacterium inhibited mycelial growth of all of the tested fungal pathogens. The fermentation broth of SG3 also effectively suppressed the development of various plant diseases including rice blast, tomato gray mold, tomato late blight, wheat leaf rust, barley powdery mildew and red pepper anthracnose. An antifungal substance was isolated from the fermentation broth of SG3 by ethyl acetate partitioning, silica gel column chromatography and preparative HPLC under the guide of bioassay. The chemical structure of the antifungal substance was determined to be rhamnolipid B by mass and NMR spectral analyses. The antifungal biosurfactant showed a potent in vivo antifungal activity against gray mold and late blight on tomato plants. In addition, rhamnolipid B inhibited mycelial growth of B. cinerea causing tomato gray mold and zoospore germination and mycelial growth of P. infestans causing tomato late blight. Pseudomonas sp. SG3 producing rhamnolipid B could be used as a new biocontrol agent for the control of plant diseases occurring on tomato plants.

• 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.

• Journal of Life Science
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• v.31 no.12
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• pp.1100-1109
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• 2021

The halophyte Artemisia scoparia is an edible medicinal plant, with insecticidal, anti-inflammatory, anticholesterol, antipyretic, and antibacterial effects. The aim of this study was to assess the inhibitory effect of crude extract and solvent-partitioned fractions obtained from A. scoparia on MMP-2 and MMP-9 activity in phorbol-12-myristate-13-acetate (PMA)-stimulated human fibrosarcoma HT-1080 cells using four different activity tests: gelatin zymography, MMP enzyme-linked immunosorbent assay (ELISA), wound healing assay, reverse transcription-polymerase chain reaction (RT-PCR), and Western blot assay. A. scoparia samples were extracted twice with methylene chloride (MC) and twice with methanol (MeOH). After the MC and MeOH crude extracts were combined, the combined crude extracts showed a significant inhibitory effect against MMP-2 and MMP-9 enzymes. They were then fractionated into n-hexane, 85% (v/v) aqueous methanol (85% (v/v) aq.MeOH), n-butanol, and water according to solvent polarity. Among the four solvent-partitioned fractions, n-hexane and 85% (v/v) aq. MeOH fractions significantly inhibited MMP-2 and MMP-9 activity and cell mobility. In addition, the n-hexane and 85% (v/v) aq.MeOH fractions effectively inhibited MMP-2 and -9 activity in the gelatin zymography and MMP ELISA assay. In the wound healing assay, RT-PCR, and Western blot assay, all solvent-partitioned fractions, except the H₂O fraction, significantly suppressed cell migration, as well as the expression levels of MMP-2 and -9 mRNA and proteins.