• International Journal of Industrial Entomology and Biomaterials
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• v.12 no.2
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• pp.63-67
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• 2006

Suppressor of cytokine signaling (SOCS) is known to playa key role as a negative feedback regulator in JAK/STAT signaling cascade in innate immunity. Our laboratory has recently been interested in elucidating the interactions between Spodoptera exigua (Se) and SeNPV. This context leads us to clone and characterize SeSOCS that may have important functions in response to SeNPV infection. Using the RT-PCR and TA cloning approach, we found a partial fragment (416 bp) of SeSOCS. Blast search and multiple alignment data showed that it has a homology to various insects such as Anopheles gambiae (78%), Aedes aegypti (75%), Drosophila melanogastar (77%), Mus musculus (69%), and Homo sapiens (69%). Temporal induction patterns of SeSOCS were analysed after being immune-challenged with either NPV or laminarin. It showed that the level of SeSOCS mRNA was strongly induced in a biphasic manner in response to SeNPV and laminarin, respectively. It seems that SOCS, a negative regulator of JAK/STAT signaling system is also present in S. exigua and may playa role in innate immunity albeit its precise role should be further elucidated at the molecular and cellular level in the early phase of SeNPV infection in larvae.

• Mycobiology
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• v.42 no.4
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• pp.385-390
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• 2014

The beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae) is difficult to control using chemical insecticides because of the development of insecticide resistance. Several pest control agents are used to control the beet armyworm. Entomopathogenic fungi are one of the candidates for eco-friendly pest control instead of chemical control agents. In this study, among various entomopathogenic fungal strains isolated from soil two isolates were selected as high virulence pathogens against larva of beet armyworm. Control efficacy of fungal conidia was influenced by conidia concentration, temperature, and relative humidity (RH). The isolates Metarhizium anisopliae FT83 showed 100% cumulative mortality against second instar larvae of S. exigua 3 days after treatment at $1{\times}10^7$ conidia/mL and Paecilomyces fumosoroseus FG340 caused 100% mortality 6 days after treatment at $1{\times}10^4$ conidia/mL. Both M. anisopliae FT83 and P. fumosoroseus FG340 effectively controlled the moth at $20{\sim}30^{\circ}C$. M. anisopliae FT83 was significantly affected mortality by RH: mortality was 86.7% at 85% RH and 13.4% at 45% RH. P. fumosoroseus FG340 showed high mortality as 90% at 45% RH and 100% at 75% RH 6 days after conidia treatments. These results suggest that P. fumosoroseus FG340 and M. anisopliae FT83 have high potential to develop as a biocontrol agent against the beet armyworm.

• Journal of Life Science
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• v.10 no.1
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• pp.1-6
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• 2000

Larval development, adult longevity and oviposition of the beet armyworm, Spodoptera exigua H bner was studied at 16, 20, 25 and 3$0^{\circ}C$ with a 16L: 8D photoperiod. Egg hatchability of S. exigua was the highest at 3$0^{\circ}C$ and reduced with decreasing temperature. Egg period was the shortest at 3$0^{\circ}C$ and prolonged with decreasing temperature. Percent pupation was became higher at higher temperature form 23.2% to 94.0%. Developmental period of larva was the shortest at 3$0^{\circ}C$, but extended with decreasing temperature. Adult emergence ratio was the highest at 3$0^{\circ}C$ and reduced with decreasing temperature. The mean pupal period was 35.2, 14.4, 7.8 and 5.0 days at 16, 20, 25 and 3$0^{\circ}C$, respectively. Relationships between constant temperature and the developmental velocity of egg, larva and pupa were linear. Developmental threshold temperature seems to be 13.3 8$^{\circ}C$ for egg, 14.02$^{\circ}C$ for larva, 14.09$^{\circ}C$ for pupa, and 13.84$^{\circ}C$ for egg the adult. Estimated value of the total effective temperature for completing each stage was 36.89 day-degree for egg, 155.72 day-degree for larva, 79.20 day-degree for pupa, and 273.41 day-degree for egg to adult. Female longevity varied to temperature from 11.4 days at 16$^{\circ}C$ to 5.8 days at 3$0^{\circ}C$, and male longevity was longer than that of female. Preoviposition period was the shortest at 3$0^{\circ}C$, but prolonged with decreasing temperature. It was about 2.7 times longer at 16$^{\circ}C$ than that at 3$0^{\circ}C$. Number of eggs per female was the highest at $25^{\circ}C$, followed by 20, 30 and 16$^{\circ}C$.

• Korean journal of applied entomology
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• v.61 no.2
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• pp.299-305
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• 2022

We investigated the occurrence and damage information of 9 species (7 families) of insect pests in two places of rucola (Eruca sativa Mill.) cultivated houses in Gyeonggi Province from 2019 to 2021, and selected five insecticides that could efficiently control the beet armyworm, Spodoptera exigua. Five insecticides (spineram SC, fluxametamide EC, chlorantraniliprole WG, cyantraniliprole DC, and emamectin benzoate EC) showed high control effects over 95% against 3^rd instar larvae of S. exigua at the two places of rucola cultivation, and there was no phytotoxicity at double dose of concentration.

• Proceedings of the Korean Society of Soil Zoology Conference
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• 1998.03a
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• pp.4-4
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• 1998

• Animal cells and systems
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• v.13 no.3
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• pp.345-350
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• 2009

We have isolated and characterized a new insect chicken type (c-type) lysozyme gene from the common cutworm, Spodoptera litura. The full-length cDNA of Spodoptera lysozyme is cloned by rapid amplification of cDNA ends PCR (RACE-PCR). The isolated cDNA consists of 1039 bp including the coding region for a 142-amino acid residue polypeptide, which included a signal peptide of 21-amino acid residue and a mature protein of 121-amino acid residue. The predicted molecular weight of mature lysozyme and its theoretical isoelectric point from amino acid composition is 13964.8 Da and 9.05, respectively. The deduced amino acid sequence of Spodoptera lysozyme gene shows the highest similarity (96.7%) to Spodoptera exigua lysozyme among other lepidopteran species. Amino acid sequence comparison with other the c-type lysozymes, Spodoptera lysozyme has the completely conserved $Glu^{32}$ and $Asp^{50}$ of the active site and eight Cys residues are completely conserved in the same position as that of other lepidopteran lysozymes.

• Journal of Microbiology and Biotechnology
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• v.19 no.3
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• pp.314-322
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• 2009

Four different bacterial colonies were isolated from an old stock of an entomopathogenic nematode, Steinernema monticolum. They all showed entomopathogenicity to final instar larvae of beet armyworm, Spodoptera exigua, by hemocoelic injection. However, they varied in colony form, susceptibility to antibiotics, and postmortem change of the infected host insects. Biolog microbial identification and 16S rDNA sequence analyses indicate that these are four different species classified into different bacterial genera. Owing to high entomopathogenicity and a cadaver color of infected insect host, Serratia sp. was selected as a main symbiotic bacterial species and analyzed for its pathogenicity. Although no virulence of Serratia sp. was detected at oral administration, the bacteria gave significant synergistic pathogenicity to fifth instar S. exigua when it was treated along with a spore-forming entomopathogenic bacterium, Bacillus thuringiensis. The synergistic effect was explained by an immunosuppressive effect of Serratia sp. by its high cytotoxic effect on hemocytes of S. exigua, because Serratia sp. caused septicemia of S. exigua when the bacterial cells were injected into S. exigua hemocoel. The cytotoxic factor(s) was present in the culture medium because the sterilized culture broth possessed high potency in the cytotoxicity, which was specific to granular cells and plasmatocytes, two main immune-associated hemocytes in insects.

• Korean journal of applied entomology
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• v.52 no.4
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• pp.295-304
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• 2013

This study aimed to understand the physiological status of the beet armyworm, Spodoptera exigua at low developmental threshold temperature (LTT) through analysis of gene-expression patterns associated with different functions (metabolism, nervous system, immune, and stress). The estimated LTTs for egg, larval, and pupal developments varied with $5.5{\sim}11.6^{\circ}C$. Larvae were able to develop at the lower temperatures than eggs and pupae. However, the physiological LTT ($15^{\circ}C$) in the fifth instar was much higher than the estimated LTT ($10.3^{\circ}C$). Gene expression patterns estimated by a quantitative RT-PCR (qRT-PCR) indicate that most genes in different functional groups increased their expressions with increase of larval instars. In the same fifth instar, as the treatment temperatures increased, the gene expression levels increased. Moreover, the newly molted fifth instar larvae were different in their gene expression rates according to their previous culturing temperatures. Most gene expressions were suppressed in the fifth instar larvae at the physiological LTT ($15^{\circ}C$). However, the larvae at $15^{\circ}C$ gradually exhibited significant increase in the gene expression rates with rearing time just like those at the higher temperature. These results suggest that S. exigua at LTT exhibits a typical gene expression pattern with maintaining significantly suppressed levels.

• Korean journal of applied entomology
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• v.32 no.2
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• pp.134-138
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• 1993

Larval densities and spatial distribution patterns of beet armyWorm, Spodoptera exigua, were studied in the welsh onion field located in Asan from June to November, 1991. During the period, there were two denslty-peaks;mid August and mid~late September. The larvae showed clumped distribution patterns. but the patterns changed into random as larval density decreased in Oct.ober. Each larval instar showed clumped pattern expect 6th instar surveyed on September 25, which distributed in a random pattern. The larval distribution pattern were also influenced by the host plants;clumped pattern on such host. as red pepper and welsh onion, versus random pattern on such hosts as chrysanthemum, peanut and soybean.

• Korean journal of applied entomology
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• v.56 no.1
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• pp.19-28
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• 2017

Polydnaviruses (PDVs) are a group of double-stranded DNA viruses symbiotic to some endoparasitoid wasps. Cotesia plutellae bracovirus (CpBV) is a PDV symbiotic to an endoparasitoid wasp, C. plutellae, parasitizing young larvae of Plutella xylostella. An early expressed gene, CpBV-ELP1, plays an important role in the parasitism by suppressing host cellular immunity by its cytotoxic activity against hemocytes. This study aimed to test its oral toxicity against insect pest by expressing it in a recombinant tobacco plant. A recombinant CpBV-ELP1 protein was produced using a baculovirus expression system and secreted to cell culture medium. The cell cultured media were used to purify CpBV-ELP1 by a sequential array of purification steps: ammonium sulfate fractionation, size exclusion chromatography, and ion exchange chromatography. Purified rCpBV-ELP1 exhibited a significant cytotoxicity against Spodoptera exigua hemocytes. CpBV-ELP1 was highly toxic to the fifth instar larvae of S. exigua by injection to hemocoel. It also showed a significant oral toxicity to fifth instar larvae of S. exigua by a leaf-dipping assay. CpBV-ELP1 was cloned into pBI121 vector under CaMV 35S promoter with opaline synthase terminator. Resulting recombinant vector (pBI121-ELP1) was used to transform Agrobacterium tumefaciens LBA4404. The recombinant bacteria were then used to induce callus of a tobacco (Nicotiana tabacum Xanthi) leaves and subsequent generation (T1) plants were selected. T1 generation tobacco plants expressing CpBV-ELP1 gave significant insecticidal activities against S. exigua larvae. These results suggest that CpBV-ELP1 gene can be used to control insect pests by constructing transgenic crops.