• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.395-402
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• 2014

BACKGROUND: Azadirachta indica Extract(AIE) containing azadirachtin as active ingredient have been used worldwide as environment-friendly organic material having pest control properties. However, the extracts prepared with different solvent and from different plant site is very diverse and have different toxicity. METHODS AND RESULTS: In this study, the four week repeated oral dose toxicity test of aqueous AIE in Sprague-Dawley rats was carried out to investigate the toxic effect of liver, main toxicity target organ of AIE. The male and female rats were divided into 4 groups, respectively; control(0 g/Kg bw), low-dose group(0.5 g/Kg bw), middle-dose(1.0 g/Kg bw) and high-dose group(2.0 g/Kg bw). As a results, relative liver weight increased with dose-dependent of AIE(p<0.05). Serum LDH in all AIE-treated groups were significantly lower than the control in male rats(p<0.05). However, serum GOT and GPT were significantly increased in all male AIE-treated groups in male rats(p<0.05) and, in particular, increase of serum GPT in dose-dependent manner raise the possibility of liver damage. Even through serum GLU was increased significantly in high-dose group in male rats compared to control, there were no significant differences of urinary GLU among all groups(p<0.05). In addition, histopathological examination of the liver did not reveal any lesions in all AIE-treated groups. CONCLUSION: In conclusion, 4 weeks of the repeated oral administration of AIE 2.0 g/Kg to rats has resulted no toxic response in liver. Therefore, AIE was no indicated to have any toxic effect in the SD rats, when it was orally administrated below the dosage 2.0 g/Kg/day for 4weeks.

• The Korean Journal of Pesticide Science
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• v.6 no.4
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• pp.250-256
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• 2002

The objective was to know if chinese cabbage growers in Gangwon alpine farmland control agricultural pests including weeds effectively and use pesticide properly. Examiners visited 185 farmers at Taebaek, Pyongchang, and Jeongseon and surveyed 33 questions on pest control methods pesticide use. Chinese cabbage farmers have noxious plant diseases such as clubroot, bacterial soft rot, downy mildew, anthracnose, and mosaic disease, and also noxious insects such as diamondback moth, aphid, beet armyworm, common cabbage worm, and Japanese native slug. In addition, farmers have noxious weeds such as common chickweed, marsh pepper, hairy crabgrass, common purslane, and horseweed. To control diseases and insects, 51.3% of farmers used many chemical agents, while 20.7% of farmers used chemical agents with too much emphasis on paraquat and glyphosate to control weeds: 87.2% of the answered farmers have a preference of the both non-selective herbicides. Farmers in the survey area selected pesticides on the basis of their own experience and sales managers' recommendation (84.2%) which results in the use of inappropriate pesticides such diniconazole. Many farmers have experienced phytotoxicities (46.7%) and pesticide poisoning (51.2%). We conclude that a systematic educational program for the proper selection and use of pesticides should be conducted for chinese cabbage growers in Gangwon alpine farmland.

• Korean journal of applied entomology
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• v.53 no.2
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• pp.193-197
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• 2014

Transgenic crops that produce insecticidal toxins have a great potential for controlling target pest insects, but there is a growing concern about unintended influences on non-target species. In the present study, the preferences and performance of non-target green peach aphid, Myzus persicae (Sulzer), on transgenic cabbages (Brassica oleracea) that produce Bt toxin (Cry1Ac1) and untransformed control plants were investigated as a part of risk assessment. In a free-choice situation, the number of nymphs larviposited by 10 winged adults over 3 days was $21.9{\pm}1.8$ and $22.5{\pm}2.2$ on transgenic and the control plants, respectively, indicating that the aphids did not discriminate between the two types of plants. In a performance assay, the development time (D) and intrinsic rate of increase (rm) of wingless aphids reared on transgenic and control plants were also similar (D, $5.8{\pm}0.2$ and $5.9{\pm}0.1$ (days) and rm, $0.7{\pm}0.1$ and $0.8{\pm}0.1$, for transgenic and control plants, respectively). These results suggest that M. persicae is not significantly affected by transgenic Bt cabbage.

• Korean journal of applied entomology
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• v.43 no.1
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• pp.61-70
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• 2004

Environmentally sound control of Japanese lawngrass cutworm, Spodoptera depravata with Korean entomopathogenic nematodes (Heterorhabditis sp. Gyeongsan, Steinernema carpocapsae GSNI , S. glaseri Dongrae, S. longicaudum Nonsan, and S. monticolum Jiri) was evaluated in the laboratory and field. In addition, effect of turf height on the pathogenicity of entomopathogenic nematodes and density of ant (Formica japonica) and spine-tailed earwigs (Forficula scudderi) were investigated in the field. The corrected mortality of 3rd instar of S. depravata larvae was 53.3% to 66.7% 5 days later after treatment of entomopathogenic nematodes. $LC_{50}$ value of S. carpocapsae GSN1 and S. monticolum Jiri against 3rd instar of S. depravata was 6.9 and 3.9, respectively. Pathogenicity of S. carpocapsae GSN1 was different depending on larval stages, i.e., mortality of 2nd instar was the highest representing 73.3% but decreased from 3rd instar. Turf height affected pathogenicity of entomopathogenic nematodes. Mortality of 4th instar of S. depravata was 40.0% by S. carpocapsae GSN1 and 33.3% by S. monticolum Jiri, and 83.3% by fenitrothion, respectively, in the turf height of 14mm, but those were lower in 45mm. The corrected mortality of S. depravata larvae was lower at the entomopathgenic nematode plots than fenitrothion plot in the distribution field of Formica japonica. However, reduction rate of F japonica was higher in fenitrothion by 56.7% compared with 0% in S. carpocapsae GSN1 and 6.7% in S. monticolum Jiri. Turf height influenced control of S. depravate in S. carpocapsae GSN1 and fenitrothion. Control value of S. carpocapsae GSN1 was 62.2% in the turf height of 3-4cm, but not effective at all in 6-8cm and 12-14cm. However, there was not significantly different in fenitrothion plots. Forficula Scudderi was also reduced only in fenitrothion plots. Reduction rate was 100% in 3-4cm, 41.7% in 6-8cm, and 16.7% in 12-14cm, respectively.

• Korean Journal of Organic Agriculture
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• v.13 no.3
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• pp.301-314
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• 2005

Insect pests were surveyed in 5 Rice paddy field areas of Organic paddy field and conventional paddy field. At the each rice-growth period, the occurrence rate of 'Small brawn plant hopper was high at the case of duck raising and rice bran farming on middle stage of rice paddy field in Gang-Hwa region. The occurrence rate of Rice water weevil was high at the conventional paddy field on the early stage of rice paddy field in Yeo-Ju region. In the Hong-Seong region, the occurrence rate of 'Rice water weevil' and 'Green rice leafhopper' was high at the 'duck raising compare to the conventional farming on the early stage of rice paddy field. According to each period, the occurrence rate of insect was high at late stage of rice paddy field, and there was no difference between each region. It showed high-occurrence tendency at duck pasture farming rice paddy field. The major natural enemies were spiders and parasites. Theridiidae and Linyphiidae were highly occurred on the conventional farming rice paddy field in Hong-Seong. Web builders containing Theridiidae, Linyphiidae and Tetragnathidae was occurred more than wandering spiders containing Lycosidae, Clubionidae and Pisauridae at various regions, and then occurrence of spiders was different at the various regions but was not different at each farming system.

• Korean Journal of Environmental Agriculture
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• v.15 no.1
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• pp.86-90
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• 1996

This study was to provide the basic information for the development of thermal weeder which uses LPG as fuel. Weed seeds of Digitaria sanguinalis S. and Portulaca oleracea L. mainly developed in fram and forestry nurseries were used as experimental samples. At different irradiation temperature(60, 80, 100, 150, $200^{\circ}C$), the dffects of weed seed species(digitalis, purslane), condition of seed(dry, soaked), and irradiation time(2, 5, 10, 20, 30, 60, 180, 300 sec) on seed viability were investigated was investigated by examining interaction and main effect of experimental factors. The results showed that viability of weed seed was significantly affected by all irradiation temperature tested. Irradiation time significantly affected on viability of weed seed on all levels of irradiation temperature. also, there were interactions between condition of weed seed and irradiation time on seed viability at each irradiation temperature.

• Journal of the Korean Chemical Society
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• v.63 no.6
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• pp.415-419
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• 2019

Fipronil is an insecticide that belongs to the N-phenylpytazole and has been used mainly for an insect pest control. However, it is known that acute poisoning of the human body causes various symptoms such as dizziness, muscle weakness, dyspnea, skin irritation, and increased heart rate. Lately, eggs containing fipronil have been distributed and toxic problems are spreading around the world. In this study, we tried to develop analytical methods to evaluate the exposure of fipronil and fipronil sulfone in animal serum samples. The differences according to mobile phase and the results of liquid - liquid extraction and solid phase extraction pretreatment method were compared. Distilled water (A) and acetonitrile (B) were selected for the mobile phase, and the pretreatment method was determined by solid phase extraction. As a result of the method validation, the intra-day / inter-day accuracies were 82.2~114.1% and the precisions were less than 20%. The detection limit was 0.027 ng/ml for fipronil and 0.087 ng/ml for fipronil sulfone. The linearity obtained was satisfying, with a coefficient of determination (r²) higher than 0.99. The concentrations in some animal sera were determined using the methods of analysis for fipronil and fipronil sulfone in animal sera developed in this study. Using the method developed in this study, it could be used as an analytical method for human bio-monitoring of fipronil and fipronil sulfone as well as animal serum.

• Korean journal of applied entomology
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• v.42 no.3
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• pp.269-277
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• 2003

Some species of true bugs have become serious problems in rice, upland crops, and tree fruits. It would be meaningful to understand research status by reviewing articles on those true bugs in Korea. Articles on those bugs published in several scientific Korean journals were reviewed, except articles on true bugs on rice plants; CD Part 1 included classification and morphological studies on eggs and larvae of Piesma spp., on external genitalia of Gonopsis affinis, and on spermathecae of some Podopinae and Asopinae species. $\circled2$ Development and growth analysis of Piesma sp., P. maculata, and 2 species of Coreidae were reviewed in part 2. $\circled3$ In part 3 we reviewed with major pest bug species on soybean, sweet persimmon, yuzu, citrus, chrysanthemum, and Cynanchum wilfordii, and insect fauna in mountain areas. $\circled4$ In part 4, damage levels in soybean, sweet persimmon, yuzu, grapes were reviewed. $\circled5$ ID In part 5 we reviewed seasonal occurrence patterns of Halyomorpha halys, Plautia stali, Riptortus clavatus in sweet persimmon orchards, of some species in soybean fields, of Nysius plebejus on chrysanthemum, and of Tropidothorax cruciger on Cynanchum wilfordii. $\circled6$ Chemical control methods in a sweet persimmon orchard, in grapevine yards, in a soybean field, and in a chrythansemum field were introduced in part 6. Some laboratory bioassay on insecticides against R. clavatus were mentioned, too. $\circled7$ Finally in part 7, researches on transmission by Halyomorpha halys and Cyrtopeltis tenuis of micoplasma-like organism which is a pathogen of paulownia withces' -broom to Catharanthus roseus were reviewed.

• Korean Journal of Environmental Agriculture
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• v.37 no.2
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• pp.135-140
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• 2018

BACKGROUND: The Asian hornet (Vespa velutina nigrithorax), a wasp species, has attacked honey bee populations and affected the beekeeping industry in Korea over the past 15 years. However, little research has been done with this invasive species. In this study, we investigated the intestine bacterial microbiota of Asian hornets and honey bees to design an attractive trap for Asian hornets. METHODS AND RESULTS: Genomic DNAs isolated from the intestine microorganisms of Asian hornets and honey bees were utilized to amplify bacterial 16S rDNA for the comparative sequence analysis. The next generation sequencing analysis identified that the orders Flavobacteriales as the most abundant intestinal microorganisms in Asian hornets, showing a clear difference compared to honey bees in which Aeromonadales are dominant. We also report five newly identified 16S rDNA sequences of Asian hornet intestinal bacteria. According to the sequence blast search, these five bacteria belong to the genera Thalassomonas, Caedobacter, Vampirovibrio, Alkaliphilus and Calothrix. CONCLUSION: While Asian hornets and honey bees show similar intestine bacterial diversity, the relative ratio of bacterial populations is different. providing useful information to design pest control agents specifically targeting Asian hornets.

• Applied Biological Chemistry
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• v.48 no.2
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• pp.150-154
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• 2005

To overcome the problems associated with chemical pesticides, biological pest controls agent extracted from Ginkgo biloba was studied. Insecticidal activities components in Ginkgo biloba extracts were analyzed using high performance liquid chromatography (HPLC). This results of HPLC analysis, GG-W80 were included bilobalide $611\;{\mu}g/kg$, ginkgolide A $37\;{\mu}g/kg$ and ginkgolide B $243\;{\mu}g/kg$, while YG-W80 were included bilobalide $214\;{\mu}g/kg$ and ginkgolide B $46\;{\mu}g/kg$. The biological activity of Ginkgo biloba extracts were conducted to repellent and pesticidial effect of Tetranichus urticae, Aphis gossypii and Myzus persicae treated with Ginkgo biloba leaves extracts. Mortalities of adult T. urticae to green Ginkgo biloba extracts (GG-W80) and yellow Ginkgo biloba extracts (YG-W80) were shown 98.3% and 20.0%, respectively. From these results, terpenes components in Ginkgo biloba extracts could be use for biological controls for T. urticae.