• Korean journal of applied entomology
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• v.31 no.2
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• pp.174-181
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• 1992

Early, mid, and late maturing soybean varieties were artificially infested with larvae of Delia platura at seeding, and then later development and productivity of soybeans were studied. In addition, in hope to utilize as possible tactics in the management of D. platura in soybeans, cultural factors such as contents of organic matter in soil, soil types, and the use of plastic mulching on the degree of damage to soybean plants by D. platura were examined. Primary leaf damage by the larva delayed the forthcoming vegetative growth but not the blooming which is initiated by the change in day length. Degree of delay in growth was more severe where leaf damage was induced by insect infestation than where artificially excised, apparently owing to simultaneous damage in stems and roots besides primary leaves. Productivity of soybeans also dropped significantly in plants with 25 % or more loss in the primary leaf area by the larva. Both transparent and black plastic mulchings shortened the period from seeding to emergence of soybean thus reducing the chance of possible attack by the larva. Soybean seedlings grown in clay loam or clay were attacked less by the larva than those in other types of soil. High organic matter content in the soil enhanced speed of emergence resulting in less larval damage to the seedling.

• Journal of Microbiology and Biotechnology
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• v.31 no.4
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• pp.529-539
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• 2021

The beet armyworm, Spodoptera exigua, is a serious insect pest infesting various vegetable crops. Two infectious insect viruses, baculovirus and iflavirus, are known to induce epizootics in S. exigua populations. Indeed, some laboratory colonies have appeared to be covertly infected by these viruses. Diagnostic PCR tests detected two different viruses: Spodoptera exigua multiple nucleopolyhedrosis virus (SeMNPV) and iflaviruses (SeIfV1 and SeIfV2). Viral extract from dead larvae of S. exigua could infect Sf9 cells and produce occlusion bodies (OBs). Feeding OBs to asymptomatic larvae of S. exigua caused significant viral disease. Interestingly, both SeIfV1 and SeIfV2 increased their titers at late larval stages. Sterilization of laid eggs with 1% sodium hypochloride significantly reduced SeMNPV titers and increased larval survival rate. Double-stranded RNA (dsRNA) specific to SeIfV1 or SeIfV2 significantly reduced viral titers and increased larval survival rate. To continuously feed dsRNA, a recombinant Escherichia coli HT115 expressing SeIfV1-dsRNA was constructed with an L4440 expression vector. Adding this recombinant E. coli to the artificial diet significantly reduced the SeIfV1 titer and increased larval survival. These results indicate that laboratory colony collapse of S. exigua is induced by multiple viral infections. In addition, either suppression of SeMNPV or SeIfV infection significantly increased larval survival, suggesting a cooperative pathogenicity between baculovirus and iflavirus against S. exigua.

• Korean journal of applied entomology
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• v.58 no.2
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• pp.101-109
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• 2019

An entomopathogenic bacterium, Xenorhabdus ehlersii KSY, is symbiotic to a nematode, Steinernema longicaudum, and exhibits high entomopathogenic virulence against lepidopteran insects. This study showed that the bacterial pathogenicity is induced by its inhibitory activity against eicosanoid biosynthesis of target insects, resulting in immunosuppression. To be applied for insect pest control, the bacteria should be infected to insect hemocoel. To deliver X. ehlersii to inset hemocoel, Bacillus thuringiensis (Bt) was mixed with the bacteria to breakdown the physical barrier (= midgut epithelium) from midgut lumen to hemocoel. The bacterial mixture significantly enhanced insecticidal activity of Bt only against larvae of Plutella xylostella and Maruca vitrata. For formulation, X. ehlersii cells were freeze-dried and mixed with sporulated Bt cells. The formulated bacterial mixture was applied to semi-field cultivating cabbage crop infested by P. xylostella. The bacterial mixture treatment showed over 95% control efficacy, while Bt alone gave 80% control efficacy. These results suggest that X. ehlersii can be applied to develop a novel insect control agent.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.117-128
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• 2022

In this study, we have examined pyrethroid actions on sodium channels in the pest insect Heliothis virescens. The synthetic pyrethroid permethrin increased steady-state sodium current in H. virescens central neurons and prolonged tail currents (I_Na-tail) due to extreme slowing of sodium channel deactivation. Prolongation of I_Na-tail was evident at permethrin concentrations as low as 60 nM, which modified ~1.7% of sodium channels and 10 μM permethrin modified about 30% of channels. The average time constant (τ₁) of tail current decay was ~335 ms for permethrin-modified channels. These modified channels activated at more negative potentials and showed slower activation kinetics, and failed to inactivate. Permethrin modification of sodium channels was dramatically potentiated by the α scorpion toxin LqhαIT, showing positive cooperativity between two binding sites. The amplitude of the tail current induced by 0.3 μM permethrin was enhanced ~8-fold by LqhαIT (200 pM). Positive cooperativity was also observed between permethrin and the insect-specific scorpion toxin AaIT as 10 nM permethrin potentiated the shift of voltage dependence caused by AaIT (~2-fold).

• Korean journal of applied entomology
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• v.62 no.4
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• pp.371-384
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• 2023

We investigated the occurrence of insect pests on street trees that were planted or naturally grew in a total of six urban and suburban parks (two sites in Iksan, one site in Gimje and three sites in Gwangju) in Honam region, South Korea from May to September, 2022. The six survey sites are divided into three characters, two 'nearby forest (NF)', two 'nearby river (NR)' and two 'nearby downtown (ND)' according to the created location of sites and the results on fauna of insect pests compared with street tree species for each character of survey sites. As results, we could discover 51 species of 49 genera in 27 families belonging to five insect orders from a total of 21 tree species belonging to 13 families in six survey sites. Among the insect taxa, hemipteran pests are most diverse with 22 species of 20 genera in 12 families and it is confirmed that Prunus × yedoensis Matsum. (Rosaceae) is damaged by most diverse 25 insect pests. With regard to character of survey sites, trees in 'nearby river' were affected by most diverse 34 insect pests, even though tree species were few compare to sites of 'nearby forest' and 'nearby downtown. Among the affected area of tree parts, leaf-feeding insect pests are most diverse with 22 species. From the present study, we provided a checklist of insect pests from the street trees and selected six most concerned species. Indeed, it is needed to conduct sustainable surveys and monitoring on occurrence of insect pests from street trees in urban and suburban parks because the species of planted street trees in parks can be extremely diverse with occurrence of unexpected insect pests.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.4
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• pp.368-383
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• 2014

Climate change is expected to affect population density, phenology, distribution, morphological traits, reproduction and genetics of insects, and even in the extinction of insects. To develop novel research subjects for predicting climate change effect, basic information about biological and ecological data on insect species should be compiled and reviewed. For this reason, this study was conducted to collect the biological information on insect pests that are essential for predicting potential damage caused by insect pests in future environment. In addition, we compared domestic and foreign research trends regarding climate change effect and suggested future research subjects. Domestic researchers were rather narrow in the subject, and were mostly conducted based on short-term monitoring data to determine relationship between insects and environmental variables. On the other hand, foreign researches studied on various subjects to analyze the effect of climate change, such as changes in distribution of insect using long-term monitoring data or their prediction using population parameters and models, and monitoring of the change of the insect community structure. To determine change of the phenology, distribution, overwintering characteristics, and genetic structures of insects under climate change through development of monitoring technique, in conclusion, further researches are needed. Also, development of population models for major or potential pests is important for prediction of climate change effects.

• The Korean Journal of Soil Zoology
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• v.9 no.1_2
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• pp.1-5
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• 2004

Insect pests and their natural enemies of Hibiscus Linne (Malvaceae) were investigated from March 2002 to November 2004. Fourteen insect pest species of 9 families in 5 orders were collected from Hibiscus syriacus: 5 species in Homoptera, 3 species in Lepidoptera, 2 species in Coleoptera, 1 species in Orthoprera, 1species in Hemiptera, 1 spedies in Acarina, and 1 species in Stylommatophora. Especially, Aphis gossypii Glover (Aphididae), Anomis megogona Walker(Noctuidae) and Tetranychus urticae Koch (Tetranychidae) were very important species because of their increasing daminge. The highest donsities were observed from May to June in August in Tetranychus urticae. As the enemies and ento-mopathogens of insect pests on Hibiscus syriacus, 1 species of bacteria, 3 species of fungi, 1 species of fungi, 1 species of Hemiptera, 1 species of Coleoptera, 2 species of Hymenopetera, 2 species of Diptera, and 1 species of Acarina were investigated. As the predators and parasitoids of Aphis gossypii, Aphidoletes aphidoletes aphidimyza Rondani (Cecidomyiidae), Meliscaeva cinctella Zetterstedt (Syrphidae), Harmonia axyridis Pallas (Coccinellidae), and Aphidius gifuensis Ashmead (Braconidae), entomopathogenic fungi, Vericillium lecani naturalis strain (Moniliaceae) and Beauveria bassiana naturalis strain strain (Hypocreaceae) were observed and Bacillus thuringiensis naturalis strain (Bacillaceae), B. bassiana, Metarhizium anisopliae naturalis strain (Hypocreaceae), predators of Tetranychus urticae, Amblyseius sp. (Phytoseiidae), and Orius sp. (Anthocoridae) were observed.

• The Korean Journal of Pesticide Science
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• v.20 no.4
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• pp.361-368
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• 2016

Japanese pine sawyer (JPS), Monochamus alternatus is a vector insect of pine wood nematode, Bersaphlenchus xylophilus in Korea and Japanese pine forest. This study was to evaluate the possibility of biological control of JPS with Korean entomopathogenic nematodes (EPNs). Korean EPNs (Heterorhabditis sp. Gyeongsan, Steinernema carpocapsae GSN1, S. glaseri Dongrae and S. longicaudum Nonsan strain) were infested bate insect, Galleria mellonella in log of dead pine tree. Result showed that, S. carpocapsae GSN1 strain has the highest pathogenicity. Heterorhabditis sp. Gyeongsan and S. carpocapsae GSN1 had infested bate insect, which located in 7.5 cm depth of pine log. EPN has pathogenicity against larva and adult of JPS. Spray application of EPNs against adult of JPS, Heterorhabditis sp. Gyeongsan strain showed higher pathogenicity than S. carpocapsae GSN1 strain. EPN infested larva of JPS was detected on bark spray treatment with S. carpocapsae GSN1 strain in dead pine log that naturally infested larva of JPS however, no EPN infested JPS was detected on soaking of pine log with suspension of S. carpocapsae GSN1 strain. Though EPN had found with low efficacy against JPS but still possible to apply to control the boring insect pest as they can control log dwelling insect.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.371-373
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• 2006

Life history of Ivela auripes (Lepidoptera: Lymantriidae), a pest of Cornus controversa, was investigated both in laboratory and field condition. At $24{\pm}1^{\circ}C$, developmental period from larvae to adult and adult life span was $26.3{\pm}0.3$ and $4.4{\pm}0.2$ days, respectively. Developmental period of pupae reared in the laboratory was not significantly different from those collected in the field. Female moths reared in the laboratory laid significantly less eggs than those emerged from the pupae collected in the field. Light trap catches was less effective than direct monitoring in the field. The two monitoring results showed that adult moth emerged from early June to late June, and the time of 50% cumulative emergence was 17 June.

• Korean journal of applied entomology
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• v.46 no.2
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• pp.275-280
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• 2007

This survey was conducted to illustrate insect pests and their natural enemies in soybean fields in Honam area. A total of 23 pest species in 13 families and 13 species of natural enemy were observed during 2002 to 2003. Delia platura, Medythia nigrobilineata, Spodoptera exigua and Aphis glycines occurred relatively with high population densities during the early growth stage of soybean. Dolycoris baccarum, Riptortus clavatus, Nezara antennata, Piezodorus hybneri and Halyomorpha halys began to occur between mid July to early August and lasted until the harvest time. Lepidopteran insect pests, Leguminivora glycinivorella, Pleuroptya ruralis, Scopula missaria, Macdunnoughia purissima and Spodoptera litura occurred significantly in late August in soybean field. Natural enemies of soybean insect pests observed in this survey were seven parasitoids, five predators, and an entomopahogenic fungus. Two egg parasitoid species for R. clavatus, two parasitoid species for P. ruralis, and five natural enemy species (including parasite, predator and entomopathogenic fungi) for either S. litura or A. glycines were identified, respectively. Among them two egg parasitoid species, Gryon japonicum and Ooenyrtus nezarae for R. clavatus, for and one parasitoid species for P. ruralis, that belong to Bethylidae, were new to Korea.