• Korean journal of applied entomology
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• v.59 no.2
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• pp.93-107
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• 2020

Adults of seven noctuid potential pests (Spodoptera frugiperda, S. litura, S. exigua, Ctenoplusia agnata, Mythimna loreyi, Athetis dissimilis, and A. lepigone) of soybean and maize in Suwon, Korea were identified by their morphological characteristics in the wing pattern and male genitalia and partial mitochondrial DNA sequences of cytochrome c oxidase subunit 1 gene. The generation number of adults that emerge annually in six species (except A. lepigone) was estimated from the data on density fluctuations of adults caught in sex pheromone traps in 2019 and the forecasted data using temperature-associated development and reproduction models for those species. S. frugiperda adults were caught from July 27th to October 31st in 2019, and hence were initially estimated to emerge three times per year. But, it was finally expected that S. frugiperda adults could possibly emerge a total of four times per year in Suwon, considering larval emergence observed during mid- and late June in other areas. Adult emergence of S. litura, S. exigua, C. agnata, and M. loreyi in 2019 was observed from May 29th to November 6th, from May 14th to November 6th, from May 26th to October 25th, and from May 31st to November 23rd, respectively. Annual adult emergence of these four species was estimated as at least four times. Adults of A. dissimilis were caught from May 26th to September 11th in 2019, and adult emergence was estimated at only twice per annum. It was postulated that the first adult populations of five species except the two Athetis species were probably migrated from other areas.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.44-50
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• 2001

Metal oxide semiconductor (MOS) structures containing nanocrystals are fabricated by using rapid thermal oxidations of amorphous silicon films. The amorphous films are deposited either by electron beam deposition method or by electron beam deposition assisted by Ar ion beam during deposition. Post oxidation of e-beam deposited film results in relatively small hysteresis of capacitance-voltage (C-V) and the flat band voltage shift, $\DeltaV_{FB}$ is less than 1V indicative of the formation of low density nanocrystals in $SiO_2$ near $SiO_2$/Si interface. By contrast, we observe very large hysteresis in C-V characteristics for oxidized ion-beam assisted e-beam deposited sample. The flat band voltage shift is larger than 22V and the hysteresis becomes even broader as increasing injection times of holes at accumulation condition and electrons at inversion condition. The result indicates the formation of slow traps in $SiO_2$ near $SiO_2$/Si interface which might be related to large density nanocrystals. Roughly estimated trap density is $1{\times}10^{13}cm^{-2}$. Such a large hysteresis may be explained in terms of the activation of adatom migration by Ar ion during deposition. The activated migration may increase nucleation rate of Si nuclei in amorphous Si matrix. During post oxidation process, nuclei grow into nanocrystals. Therefore, ion beam assistance during deposition may be very feasible for MOS structure containing nanocrystals with large density which is a basic building block for single electron memory device.

• Korean journal of applied entomology
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• v.30 no.4
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• pp.249-257
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• 1991

Chronological changes in the occurrence pattern of the striped rice borer(SRB), Chilo suppressalis Walker, were investigated by analyzing the data collected by 33 light traps of the countrywide monitoring units during the period of 1968-1989. And also relation of incidences between larval and adult populations, emergence time and percent emergence of overwintered larvae were observed in relation to the time of different rice transplantations. Spring moths of SRB in 1985-'89 generally emerged earlier than in 1968-'72 : 30 days earlier at Kwangju, 20 -25 days earlier at Sangju and Naju, 10-15 days earlier at Uljin, Jinju, Goyang, Milyang, Kimhae, etc., 5 days earlier at Suweon, Jinchun, Daejeon, Namweon, Haenam, etc. There was no change in the time of spring moth emergance at Weonseong, Chungju, Seosan, Yongju, and Nonsan. Summer moths of SRB in 1985- '89 also emerged earlier than 1968- '72: 20 days earlier at Uljin, 15 days earlier at Chungju, Yeongdug, and Habchun, 5-10 days earlier at the other areas except Yeongju. There was an overall countrywide decrease in the population of the 1st generation of SRB during the last two decades. The population of the 2nd generation also decreased in 19 areas during the same period, but increased in 14 areas including over 3-fold increases in Kwangju, Naju and Daegu, and double increase in Jinju, Milyang and Gongju. The higher larval population density of 1st genration was taken place in the earlier transplanted fields, whereas the population of 2nd generation were higher at mid-season transplanted (May 30), followed by May 15, June 15, and April 30. The peak of larval population appeared generally 15 days after moth peak in 1st generation, and 10 days after moth-peak in 2nd generation. The earlier transplanted fields were the higher percent damage due to 1st off-springs of spring moths, whereas the fields transplanted in mid-season were higher damage due to 2nd off-springs of summer moths. Average body weights of SRB larvae before overwintering were 65.6 mg, 61.2 mg, and 55.5 mg in early, mid-season, and late transplantations, respectively. In field cage experiments, emergence rate of the overwintered larvae ranged from 28.3-39.8%. In other words, body weights of overwintering larvae were heavier in fields by earlier transplantation, and heavier larvae showed higher percentage of adult emergence. The period from overwintered larvae to adult emergence was longer in the fields of the later transplantations; namely, 44, 49, and 51 days for early, mid-season, and late transplantations, respectively.

• Korean journal of applied entomology
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• v.54 no.4
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• pp.383-392
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• 2015

We investigated the induction of pupal diapause and number of generation for H. armigera using outdoor rearing and sex pheromone trapping in Suwon, Korea. Over-wintering pupae were induced when neonate larvae were reared in the outdoors from late Aug. to early Oct. in 2013 and 2014. H. armigera adults emerged from late May to early Jun. for 2013 colonies and from late May to late Jun. for 2014 colonies. The colonies placed after mid September produced only diapause pupae, to show environmental conditions that day-lengths on the rearing start date were 11 h 49 min~12 h 24 min, and mean temperatures before pupation were $14.8{\sim}20.7^{\circ}C$. Summer diapause was not observed in all colonies. The peak occurrence of H. armigera adults from sex pheromone trap in Suwon and Hwaseong were pooled and showed four generations (1st: from late Apr. to mid Jun., 2nd: from mid Jun. to late Jul., 3rd: from mid Jul. to late Aug., 4th: from late Aug. to mid Oct.). A degree-day model for development of H. armigera developed by Mironidis and Savopoulou-Soultani (2008) was used to validate the number of generation from field observations using pheromone traps. The 3rd and over-wintering generations were mainly overlapped. It was decided that H. armigera has one over-wintering and three complete generations in a year, and diapause is induced from offsprings of the 3rd and 4th generations adults. It is expected that larvae of the 1st and 2nd generations give a damage to ear zone in maize fields in which have been planted during April.

• Korean journal of applied entomology
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• v.56 no.4
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• pp.319-329
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• 2017

We investigated the host preference of Ricania app. at different developmental stages to select the effective control methods. Ricania spp. at different developmental stages preferred different host plants. During the nymphal period, individuals moved to the bottom due to environmental factors such as wind and rain, rather than inhabiting trees, and fed on various plants ranging from 1 year-old herbaceous plants to shrubs. Especially, at Palbong Mt. in Gonju, Ricania spp. nymphs preferred Symplocos chinensis f. pilosa, Celastrus orbiculatus, Euonymus alatus, Kalopanax septemlobus, Aralia elata, Styrax japonicas, Rubus parvifolius, Ru. coreanus, Ru. crataegifolius, Quercus acutissima, Cornus officinalis, Lespedeza bicolor, Albizia julibrissin, L. maximowiczii, Rhododendron schlippenbachii and Rh. indicum. At Yongbong Mt. in Hongseong, Ricania spp. adults preferred herbaceous plants, such as Helianthus annuus, Solanum nigrum, and Oenothera biennis rather than trees during the pre-oviposition stage. Subsequently, as the oviposition season began, Ricania spp. adults were rarely found in H. annuus, S. nigrum, or O. biennis and appeared to migrate to the perennial trees and shrubs hosts to lay eggs. At Palbong Mt., the main laying hosts of Ricania spp. adults were Weigela subsessilis, Ailanthus altissima, Q. aliena, Boehmeria platanifolia, Diospyros lotus, Ziziphus jujubae var. inermis, St. japonicus, Prunus mume, P. serrulata var. spontanea, Spiraea prunifolia f. simpliciflora, Ru. crataegifolius, Salix koreensis, Ru. yedoense f. poukhanense, and Co. controversa. The degree of egg laying, number of egg masses and adult Ricania spp. were significantly higher in sunlit areas than in shaded areas, in addition, the lower the altitude, the more adults were present. This study contributes toward the development of traps that can attract and control Ricania spp. and reduce the density of Ricania spp. that disturb the ecosystem.

• Korean Journal of Environment and Ecology
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• v.33 no.5
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• pp.506-514
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• 2019

Unlike natural ecosystems, the urban ecosystem proVides an interdependent enVironment in which wild organisms and urban people co-exist. Hornets (genus Vespa) appearing in urban green and parks haVe a positiVe effect on urban ecosystems, but they also cause ecosystem disserVices that cause physical and psychological discomforts to the urban people. Children's parks, for example, are Very popular among children and residents for easy accessibility, and hornets also use them as bases and habitats. HoweVer, there is still a lack of spatial analysis of habitats and appearance characteristics of hornets in children's parks. This study installed hornet traps in 27 children's parks in Cheonan from April to NoVember 2018 in consideration of the life cycle of hornets. We captured a total of fiVe Vespa species (Vespa crabro, V. analis, V. mandarinia, V. ducalis, and V. Velutina) for 32 weeks and analyzed the emergence of hornets in relation to the composition of seasonal characteristics, species characteristics, and enVironmental spatial information. We captured a total of 818 hornets during the study period. They included 290 V. analis (35.4%), 260 V. crabro (31.8%), 100 V. ducalis (12.1%), 87 V. mandaninia (10.6%), and 81 V. Velutina(9.9%). Most of the hornets showed a common feature that queen hornets were largely captured in May through June after they awake from hibernation, and the number of caught hornets decreased sharply beginning in mid-June, which was the cooperatiVe period. HoweVer, V. Velutina showed a seasonal specificity that more than 80% were captured beginning in the third week of October when other hornet species had already entered a decline phase. The analysis of the number of hornets caught in each spot in children's parks showed significant difference among the spots as 363 hornets (44.3%) were captured in top children's parks, and 35 hornets (4%) were captured in bottom children's parks. In particular, the mean NDVI (Normalized difference Vegetation index) of the top six children's parks was 0.79, and that of the bottom six children's parks was 0.38 (t=2.67*, *=p<0.05), indicating a significant difference. The frequency of capturing hornets was high when the ground around the children's parks was grass or bare land. This study is meaningful as a reference study that confirms the ecological characteristics of hornets appearing in green and parks in the city. We expect it to be a foundation for effectiVe urban green area management in the future.

• Korean journal of applied entomology
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• v.58 no.3
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• pp.183-187
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• 2019

To establish the cooperative monitoring network which can investigate introductions or outbreaks of high risk insect pests into Korea, seven universities, Gyeongsang National University, Kunsan National University, Seoul National University, Sunchon National University, Andong National University, Jeju National University, and Chungbuk National University, carried out seven regions' monitoring about nine high risk insect pests, Aceria diospyri, Bactrocera dorsalis, Bactrocera minax, Bactrocera tsuneonis, Cydia pomonella, Lobesia botrana, Proeulia sp., Solenopsis invicta, Stephanitis takeyai, from June to October in 2018. A total of 7,560 traps/visual scouting were investigated in 315 points of 105 local sites of seven regions, resulting the nine species, A. diospyri, B. dorsalis, B. minax, B. tsuneonis, C. pomonella, L. botrana, Proeulia sp., S. invicta, and S. takeyai, were not detected. From this study, we established the nationwide monitoring system which can early detect high risk insect pests and secured a bridgehead for monitoring invasive insect pests passing the border.

• Korean journal of applied entomology
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• v.58 no.2
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• pp.89-99
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• 2019

In total, 654,362 adult mosquitoes were captured using black light traps in Gangwon-do Province of the Republic of Korea from 2012 to 2017. The collected mosquitoes were identified to the species level, placed in pools of up to 50 mosquitoes each, by species and date of collection, and screened for flaviviruses using a reverse transcription-polymerase chain reaction assay. A total of 276,224 adult mosquitoes were grouped in 7,721 pools for virus testing, and 68 flavivirus positive pools (0.9%) were detected. Flavivirus-positive products were confirmed by DNA sequencing. Japanese encephalitis viruses were detected in single pools collected from Chuncheon (2012, 2017: Culex pipiens, 2,728 and 1,111 mosquitoes, respectively), Hoengseong (2013: Culex orientalis, 19), and Gangneung (2017: C. pipiens, 724). All the Japanese encephalitis viruses detected were revealed as genotype V. Chaoyang viruses were detected in 63 pools of 5,055 Aedes vexans nipponii and a single pool of 585 C. pipiens collected in Gangwon-do Province from 2012 to 2017. Chuncheon was the region with the highest minimum infection rates (MIR, 0.32) and maximum likehood estimate (MLE, 0.33; confidence interval (CI) 95%, 0.23-0.46) of A. vexans nipponii for Chaoyang virus, followed by Hoengseong (MIR 0.30, MLE 0.30, CI 0.16-0.52) and Gangneung (MIR 0.21, MLE 0.21, CI 0.13-0.31). Monthly MIR and MLE values of A. vexans nipponii for Chaoyang virus were the highest in October (MIR 0.38, MLE 0.38, CI 0.07-1.25).

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.3
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• pp.208-220
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• 2019

The seasonality of leaf fall has important implications for understanding the response of trees' phenology to climate change. In this study, we quantified the leaf fall pattern with a model to estimate the timing and speed of leaf litter according to species and considered the nutrient use strategy of canopy species. In the autumns of 2015 and 2016, leaf litter was collected periodically using 36 litter-traps from the deciduous forests in Gwangneung and sorted by species. The seasonal leaf fall pattern was estimated using the non-linear regression model of Dixon. Additionally, the resorption rate was calculated by analyzing the nitrogen concentration of the leaf litter at each collection time. The leaf litter generally began in early October and ended in mid-November depending on the species. At the peak time (T50) of leaf fall, on average, Carpinus laxiflora was first, and Quercus serrata was last. The rate of leaf fall was fastest (18.6 days) for Sorbus alnifolia in 2016 and slowest (40.8 days) for C. cordata in 2015. The nitrogen resorption rates at T50 were 0.45% for Q. serrata and 0.48% for C. laxiflora, and the resorption rate in 2015 with less precipitation was higher than in 2016. Since falling of leaf litter is affected by environmental factors such as temperature, precipitation, photoperiod, and $CO_2$ during the period attached foliage, the leaf fall pattern and nitrogen resorption differed year by year depending on the species. If we quantify the fall phenomena of deciduous trees and analyze them according to various conditions, we can predict whether the changes in leaf fall timing and speed due to climate change will prolong or shorten the growth period of trees. In addition, it may be possible to consider how this affects their nutrient use strategy.

• Korean Journal of Environmental Biology
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• v.39 no.3
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• pp.362-373
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• 2021

This study was conducted to establish mosquito distribution density and habitat in Sejong city for the prevention of mosquito-borne infectious diseases. The overall distribution of mosquitoes in the Sejong City was investigated, and the population density of mosquitoes in the old and new city was analyzed. Mosquito populations were determined using MOSHOLE and Blacklight traps once a week overnight. We also compared the mosquito population density of the old city and the new city, and the daily mosquito population was calculated using the data from the smart mosquito trap(DMS). Of all the study sites, Geumnam-myeon had the highest number of mosquitoes captured, and the dominant species were Armigeres subalbatus and Culex pipienspallens. Mosquito species with the potential for transmitting diseases were mainly found in Yeonseo-myeon (106 individual), and Geumnam-myeon (101). Mosquito collection rates by MOSHOLE trap and Blacklight trap were 58.49% and 41.51%, respectively. We concluded that using CO₂ would be the most suitable approach for collecting mosquitoes. The mosquito population density in the old city (92.05±7.04) was approximately twice that of the new city(51.50±4.05). Since Sejong City is divided into old city and new city, it is difficult to spot remarkable effects in a standardized way. For effective quarantine, differentiation of quarantine must be established. This study results provide a basis for Sejong City's integrated mosquito control guidelines, and therefore effective control of which we believe will help control the spread of mosquito-borne diseases and reduce damage from mosquitoes.