• Korean journal of applied entomology
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• v.50 no.2
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• pp.131-139
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• 2011

This study investigated the adverse effects of sound treatment on physiological processes of the American leafminer, Liriomyza trifolii, during several developmental stages. Larval feeding activity was analyzed by measuring feeding tunnel length. It was significantly suppressed by sound treatment (5,000 Hz, 95 dB). Sound treatment delayed the pupal period at 315 - 5,000 Hz and prevented adult emergence at 1,000 - 5,000 Hz. Female oviposition was also inhibited by the stress sound treatments. However, phototactic adult movement was not affected by sound treatment. Pupae treated with 5,000 Hz showed marked changes in protein patterns analyzed by two dimensional electrophoresis. MALDI-TOF analysis of specific protein spots indicated that trafficking protein particle complex I, triosephosphate isomerase, hypothetical protein TcasGA2_TC013388, polycystin-2, paraneoplastic neuronal antigen MA1, and tropomyosin I (isoform M) were predicted in the control insects and disappeared in the insects treated with sound. By contrast, DOCK9, cytoskeletal keratin II, and F0F1-ATP synthase beta subunit were predicted only in the sound-treated insects. Furthermore, stress sound significantly increased the susceptibility of L. trifolii to insecticides. These results suggest that physiological processes of L. trifolii are altered by sound stress, which may be exploited to develop a novel physical control tactic against L. trifolii.

• Journal of Life Science
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• v.29 no.2
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• pp.164-172
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• 2019

In Korea, shiitake mushroom, Lentinula edodes, is cultivated on artificial medium containing oak sawdust and wheat bran. The annual production of spent mushroom substrate (SMS) of shiitake, a byproduct of the mushroom industry, is estimated to reach over 50,000 tons per year. This study aimed to improve the use of SMS as a novel bioresource. Hot water extracts of SMS after the first and third harvest were prepared and their bioactivities evaluated. Hot water extracts of uninoculated medium and shiitake were used as controls. Extracts of SMS showed higher radical scavenging of DPPH anions, ABTS cations, nitrites, and a higher reducing power than those of shiitake or medium extracts. After the first and third harvests at 0.5 mg/disc, SMS extracts showed no antibacterial or antifungal activities against the pathogenic and food-spoilage bacteria and fungi. However, they showed good inhibitory activities against ${\alpha}$-glucosidase at 0.5 mg/ml. In addition, SMS extracts had strong anti-coagulation activities via their inhibition of thrombin, prothrombin, and blood coagulation factors without platelet aggregation activity. Our results suggested SMS should no longer be perceived as a useless byproduct but should be understood as a novel bioresource, the extracts of which could be developed as antioxidant, antidiabetic, and antithrombosis agents.

• The Plant Pathology Journal
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• v.34 no.5
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• pp.445-450
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• 2018

Bacteriophages, bacteria-infecting viruses, have been recently reconsidered as a biological control tool for preventing bacterial pathogens. Erwinia amylovora and E. pyrifoliae cause fire blight and black shoot blight disease in apple and pear, respectively. In this study, the bacteriophage phiEaP-8 was isolated from apple orchard soil and could efficiently and specifically kill both E. amylovora and E. pyrifoliae. This bacteriophage belongs to the Podoviridae family. Whole genome analysis revealed that phiEaP-8 carries a 75,929 bp genomic DNA with 78 coding sequences and 5 tRNA genes. Genome comparison showed that phiEaP-8 has only 85% identity to known bacteriophages at the DNA level. PhiEaP-8 retained lytic activity up to $50^{\circ}C$, within a pH range from 5 to 10, and under 365 nm UV light. Based on these characteristics, the bacteriophage phiEaP-8 is novel and carries potential to control both E. amylovora and E. pyrifoliae in apple and pear.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.241-259
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• 2006

Polydnavirus is a mutualistic DNA virus found in some braconid and ichneumonid wasps. Its genome is integrated into host chromosome as a provirus. Its replication occurs at ovarian calyx epithelium during host pupal stage to form episomal viral particles. The viral particles are delivered into hemocoel of the parasitized insect along with eggs during wasp oviposition. Several polydnaviral genomes, which are isolated from the episomal virus particles, have been sequenced and exhibit some gene families with speculative physiological functions. This review presents the viral characteristics in terms of Its parasitic physiology. For developing new insect pest control tactics, it also discusses several application strategies exploiting the viral genome to manipulate insect physiology.

• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.279-286
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• 2015

Cotesia plutellae bracovirus (CpBV) is a polydnavirus symbiotic to C. plutellae parasitizing young larvae of the diamondback moth, Plutella xylostella. Several CpBV genes play important roles in suppressing immune responses of the parasitized larvae. This study tested a hypothesis that the CpBV genes inducing host immunosuppression could be applied to develop a potent recombinant baculovirus. Based on a previous study, a recombinant baculovirus expressing CpBV-ELP1 (AcMNPV-ELP1) was selected and multiplied using larvae of the beet armyworm, Spodoptera exigua. The recombinant viruses were produced in a yield of $5{\times}10^{10}$ polyhedral inclusion body (PIB)/larva. The cultured AcMNPV-ELP1 exhibited a much higher pathogenicity against S. exigua larvae. However, its insecticidal activity was varied among larval instars of S. exigua, in which first and late instars were high susceptible. Spray of the recombinant baculovirus ($5{\times}10^6PIB/mL$) exhibited higher control efficacy (${\approx}$ 88%) against S. exigua larvae infesting cabbage than a chemical insecticide, tebufenozide, at 7 days after treatment. These results indicate that AcMNPV-ELP1 mass-cultured using host insect system is highly pathogenic and can be applied to develop a novel microbial control agent.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.349-356
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• 2012

Eicosanoid mediates various cellular immune responses in insects. This study aimed to discover its novel action on the modulation of hemocyte populations in response to an immune challenge. Upon bacterial challenge, the last instar larvae of the beet armyworm, Spodoptera exigua, increased their total hemocyte density in 2 h, and then decreased it to a basal hemocyte density level. This rapid increase in total hemocyte density was explained by an increase of plasmatocyte and spherulocyte densities. When larvae were treated with dexamethasone (a specific phospholipase $A_2$ ($PLA_2$) inhibitor), they did not show any increase in hemocyte density in response to bacterial challenge. However, the addition of arachidonic acid (a catalytic product of $PLA_2$) to larvae treated with dexamethasone recovered the up-regulation of hemocyte density in response to bacterial infection. Among eicosanoid, cyclooxygenase (COX), but not lipoxygenase (LOX), products seemed to mediate the increase of hemocyte density in response to bacterial infection because naproxene (a COX inhibitor) inhibited the hemocyte density increase, though esculetin (a LOX inhibitor) did not. Prostaglandin $E_2$, a COX product, significantly increased the hemocyte density even without bacterial infection. These results suggest that eicosaniod mediates a rapid increase in total hemocyte density in response to immune challenge.

• The Korean Journal of Pesticide Science
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• v.11 no.3
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• pp.164-170
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• 2007

The concept of innate immunity in insects which refers to the first line of host defense constitutes the humoral and cellular components which are involved in recognition and actively participate in the elimination of the intruding foreign micro- or macro-organisms. Several recent studies suggest that juvenile hormone (JH) modulates the cellular immune reactions in response to pathogen. In this study, pyriproxyfen (a JH agonist as an insect growth regulator) was tested in its any inhibitory effect on the immune reactions of the beet armyworm, Spodoptera exigua. To this end, five different hemocyte morphotypes of final instar S. exigua were identified by phase contrast microscopy. Plasmatocytes and granular cells, which constitute about 90% of the total hemocyte count, were prominently distinguished based on their basophilic/acidophilic nature using Giemsa stain. The role of pyriproxyfen on the functional ability of hemocytes was analyzed using FITC-labeled Providencia vermicola for the phagocytic potential of the hemocytes. Both granular cells and plasmatocytes exhibited phagocytosis behavior. Pyriproxyfen significantly inhibited the phagocytosis of both cell types, proposing its novel action as an immunosuppressant.

• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.1023-1029
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• 2023

Biosurfactants reduce surface and interfacial tension due to their amphiphilic properties and are an eco-friendly alternative for chemical surfactants. In this study, a new yeast strain JAF-11 that produces a biosurfactant was selected using drop collapse method, and the properties of the extracts were investigated. The nucleotide sequences of the strain were compared with closely related strains and identified based on the D1/D2 domain of the large subunit ribosomal DNA (LSU) and internal transcribed spacer (ITS) regions. Neodothiora populina CPC 39399^T, the closest species with strain JAF-11, showed a sequence similarity of 97.75% for LSU and 94.27% for ITS, respectively. The result suggests that the strain JAF-11 represents a distinct species that cannot be assigned to any existing genus or species in the family Dothideaceae. Strain JAF-11 produced a biosurfactant reducing the surface tension of water from 72 mN/m to 34.5 mN/m on the sixth day of culture and the result of measuring the critical micelle concentration (CMC) by extracting the crude biosurfactant was found to be 24 mg/l. The molecular weight 502 of the purified biosurfactant was confirmed by measuring the fast atom bombardment mass spectrum. The chemical structure was analyzed by measuring ¹H nuclear magnetic resonance (NMR), ¹³C NMR, and two-dimensional NMRs of the compound. The molecular formula was C₂₆H₄₆O₉, and it was composed of one octanoyl group and two hexanoyl groups to myo-inositol moiety. The new biosurfactant is the first report of a compound produced by a new yeast strain, JAF-11.

• The Plant Pathology Journal
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• v.25 no.1
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• pp.38-46
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• 2009

Lichen-forming fungi (LEF) were isolated from 67 Hungarian lichen species from ascospores or thallus fragments. LFF were successfully isolated from 26 species with isolation rate of 38.8%. Of the total number of isolation from ascospores (27 species) and thallus fragments (40 species), 48% and 32.5% of the species were successfully isolated, respectively. Comparison of rDNA sequences of ITS regions between the isolated LFF and the original thallus confirmed that all the isolates originated from the thallus fragments were LEF. The following 14 species of LEF were newly isolated in this study; Acarospora cervina, Bacidia rubella, Cladonia pyxidata, Lasallia pustulata, Lecania hyaline, Lecanora argentata, Parmelina tiliacea, Parmotrema chinense, Physconia distorta, Protoparmeliopsis muralis, Ramalina pollinaria, Sarcogyne regularis, Umbilicaria hirsuta, Xanthoparmelia conspersa and X. stenophylla. Antifungal activity of the Hungarian LFF was evaluated against plant pathogenic fungi of Colletotrichum acutatum, C. coccodes and C. gloeosporioides, causal agent of anthracnose on hot pepper. Among the 26 isolates, 11 LFF showed more than 50% of inhibition rates of mycelial growth of at least one target pathogen. Especially, LFF of Evernia prunastri, Lecania hyalina and Lecanora argentata were remarkably effective in inhibition of mycelial growth of all the tested pathogens with antibiotic mode of action. On the other hands, five isolates of Cladonia furcata, Hypogymnia physodes, Lasallia pustulata, Ramalina fastigiata and Ramalina pollinaria exhibited fungal lytic activity against all the three pathogens. Among the tested fungal pathogens, C. coccodes seemed to be most sensitive to the LFF. The Hungarian LFF firstly isolated in this study can be served as novel bioresources to develop new biofungicides alternative to current fungicides to control hot pepper anthracnose pathogenic fungi.

• The Plant Pathology Journal
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• v.27 no.3
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• pp.207-224
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• 2011

Diseases caused by plant pathogenic bacteria constitute an emerging threat to global food security. Xanthomonas is a large genus of Gram-negative bacteria that cause disease in several host plants leading to considerable losses in productivity and quality of harvests. Despite the ranges of controlling techniques available, the microbiological safety of economically important crops and crop plants including fruits and vegetables continues to be a major concern to the agriculture industry. On the other hand, many of the currently available antimicrobial agents for agriculture are highly toxic, non-biodegradable and cause extended environmental pollution. Besides, the use of antibiotics has provoked an increased resistance among the bacterial pathogens and their pathovars. Thus, novel efficient and safe remedies for controlling plant bacterial diseases are necessary. There has been an increasing interest worldwide on therapeutic values of natural products such as essential oils, hence the purpose of this review is to provide an overview of the published data on the antibacterial efficacy of essential oils that could be considered suitable for application in agriculture as biocontrol measures against plant pathogenic bacteria of Xanthomonas species. The current knowledge on the use of essential oils to control Xanthomonas bacteria in vitro and in vivo models has been discussed. A brief description on the legal aspects on the use of essential oils against bacterial pathogens has also been presented. Through this review, a mode of antibacterial action of essential oils along with their chemical nature and the area for future research have been thoroughly discussed.