• Korean journal of applied entomology
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• v.29 no.1
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• pp.20-24
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• 1990

Studies were carried out to investigate the overwintering densities of spider mites, hatching rate and time of P. ulmi eggs, and seasonal occurrences of spider mites (P. ulmi and T. urticae) in apple orchards of Kyungpook province from 1987 to 1989. Overwintering density of P. ulmi eggs was higher in Kunwi, Andong, Chilgok but lower in Kyungju. Overovintering densities of T. urticae were high in all the regions. With the hatching time and rate for P. ulmi eggs, the first hatching ate was April 14, and the last was May 3, and the average hatching rate was 89.3%. The density of P. ulmi was high from early May to middle July and T. urticae begin to increase rapidly from middle June and then was continuously high upto fruit harvesting time.

• Korean journal of applied entomology
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• v.44 no.2
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• pp.115-123
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• 2005

Historical changes of population abundances of European red mite (ERM), Panonychus ulmi (Koch), and two-spotted spider mite (TSSM), Tetranychus urticae (Koch) (Acari: Tetranychidae), were described in selected apple orchards in the National Horticultural Research Institute (NHRI, Suwon, Korea), based on research reports of the NHRI from 1958 to 1998. ERM was an abundant species up to 1970, and TSSM became a dominant species after 1980. The change occurred around mid 1970. Three hypotheses were made to explain the change: TSSM competitively replaces ERM, ground cover weeds are a major influencing factor on movement of TSSM (TSSM movement into trees is accelerated by destroying weeds), and ERM and TSSM populations are regulated by natural enemy complexes when the orchard system is not disrupted. And long-term results of the interaction between two species were projected according to the combination of different orchard management strategies: pesticide sprays (non-selective toxic pesticide spray : heavy pesticide pressure (HPP), and selective soft pesticide spray = low pesticide pressure (LPP)) and weed control methods (grass planting, and clean culture system with herbicides). In the HPP and grass planting system, ERMs are abundant because ERM can avoid competition with TSSM as movement of TSSM to trees are restricted, and natural enemy complexes are destroyed by toxic pesticides. In the HPP and clean culture system, TSSMs are abundant because TSSM moves to trees from early season and competitively replaces ERM. In the LPP and grass planting system, ERMs are abundant because movement of TSSM to trees is reduced, but they do not build up a high population density since their densities are regulated by natural enemy complexes. In the LPP and clean culture system, TSSM moves to trees and competes with ERM, but the competition pressure is reduced because population densities of mites are regulated in a lower level by natural enemy complexes. So, ERM can occurs in late season. Thus, two species can coexist temporarily with more ERM in early season and more TSSM in late season. TSSM abundant phenomenon presented in this study can be partially explained as a result of long-term interaction between ERM and TSSM under the HPP and clean culture system.

• Korean journal of applied entomology
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• v.53 no.4
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• pp.415-425
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• 2014

This study investigated population fluctuations in two mite species in apple orchards over 20-year period. The occurrence of two major mite pests infesting apple trees, two-spotted spider mite Tetranychus urticae and European red mite Panonychus ulmi (Acari: Tetranychidae), was investigated from 1992 to 2011 in major apple-producing districts, including four to eight cities, in the southern part of the Republic of Korea. The 20-year trend revealed that more orchards were infested by T. urticae from 1992 to 1999, but thereafter P. ulmi became dominant. The observed mean density of P. ulmi was consistent, whereas that of T. urticae fluctuated during this period. The analysis of occurrence in four time periods reveals that the density of T. urticae decreased after 2002. The monthly sampling, revealed that the density of P. ulmi was higher in April, whereas the density of T. urticae was higher from May to August. This change may be due to a change in the frequency of pesticide spraying, ground vegetation management, a decrease in nitrogen fertilization, and the overall orchard management practices. However, this projection should be examined in more detail. On the basis of the findings of this study, it can be concluded that cultural practices, including fertilization, and environmental changes, such as pesticide spray frequency and integrated pest management practices, affect species dominance and population densities of the two mite species in apple orchards.

• The Bimonthly Magazine for Agrochemicals and Plant Protection
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• v.6 no.6
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• pp.63-73
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• 1985

최근에 과수농가의 농민과 원예 및 능금조합의 지도기사들을 대상으로 과수해충 방제실태에 대한 설문조사를 한 결과, 사과원에서는 응애류가 심식충류나 진딧물보다 방제가 어려운 해충으로 지적되고 있다. 또한 필자가 전국 6개 지역의 15개 일반 농가의 사과원을 2년간 년 3회 이상 관찰한 결과에서도 심식충류의 피해를 받고 있는 농가는 거의 없었으며, 응애류는 그 발생정도에 차이는 있으나 대부분의 사과원에서 상존하고 있는 현상이었다. 이와 같이 응애류가 사과원에서 주요해충으로 등장하게 된 이유는 첫째, 시비$\cdot$농약살포 등 관리상태의 향상으로 사과나무 잎의 생리적 조건이 변화되어 응애류의 생식력을 자극시켰기 때문이라는 ''생식자극설''(生殖刺戟設)과 둘째, 1940년대 후반 이후 농약 사용의 급증으로 인하여 응애류의 발생을 억제하던 포식성 응애를 비롯한 천적류가 감소 또는 멸종되었기 때문에 응애류가 격발(激發)하게 되었다는 ''포식자억제설''(捕食者抑制設) 등이 있다.

• Korean journal of applied entomology
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• v.42 no.3
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• pp.185-195
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• 2003

Phytoseiid mites are important predators of spider mites, rust mites and many of insect pests as well. From two-year (2001-2002) survey of apple orchards in Kyoungbuk and Suwon area, 13 species of phytoseiids, 12 species of the genus Amblyseius and one species of the genus Typhlodromus were found. Among them, Amblyseius womersleyi was the most dominant followed by A. rademacheri, A. orientalis, and A. makuwa. Amblyseius rademacheri and A. makuwa were mainly found from ground vegetation. Keys to genera and species were presented with some pictorial details and ecological notes of each species. Further discussion on systematics of the family Phytoseiidae and use in apple IPM were suggested.

• Animal Systematics, Evolution and Diversity
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• v.2 no.2
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• pp.13-26
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• 1986

A Taxonomic investigation was carried out on the following seven spider mites (Family tetranychidae) by comparison of morphological characters, cuticular lobes and karyotypes. Materials used in this study were collected and reared at Jeonju, Jorea during October 1985-June 1986. Subfamily Bryobiinae ; Bryobia praetiosa Koch, 1836 ; Petrobia latens (Mller, 1776). Subfamily Tetranychinae ; Panonychus citri (McGregor , 1919) ; P.ulmi (Koch, 1836): T vienensis tranychus Zacher , 1920 ; T.urticae (Koch, 1836) ; T. kanzawai Kishida , 1927. Of them two species, P. latens and T. kanzawai , are newly recorded from Korea.

• Korean journal of applied entomology
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• v.60 no.1
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• pp.63-70
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• 2021

Two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae) is one of the major pests in apple orchards. TSSM was known to show different population dynamics depending on apple cultivars. We tested the host plant preference and fitness of TSSM on the leaves of 3 apple cultivars, Fuji, Tsugaru, and Hongro. TSSM showed higher behavioral preference to Fuji than Tsugaru and Hongro, and showed a higher fecundity in Fuji. The immature development of this mite was the shortest in Fuji and longest in Hongro. Total fecundities were not significantly different among cultivars, but daily fecundity was higher and longevity was lower in Fuji. Hongro was the less preferred cultivar for TSSM, and showed the lowest fitness by life table parameters. These results could explain the possible mechanisms of differential population dynamics among apple cultivars. Further study including diverse apple cultivars currently available in Korea could help to deploy time- and cultivar- specific IPM tactics.

• Korean journal of applied entomology
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• v.42 no.3
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• pp.257-262
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• 2003

Spider mites and their predacious mites were surveyed in an apple orchard where pesticides have not been applied for a long time, to understand the undisrupted predacious mite complex and their role in the controling spider mites. Spider mites occurring in the orchard were different to those in conventional orchards. A few Tetranychus urticae and Panonychus ulmi were observed, while T. kanzawai was abundant during growing season. Four species of phytoseiids, Amblyseius eharai, A. kokufuensis, A. womersleyi and Typhlodromus vulgaris, and one stigmaeid species of Agistemus terminalis were observed from leaf samples in the orchard. Among them, T. vulgaris occurred from early cool season with low T. kanzawai densities through to mid-and late-season. A. womersleyi was observed only during mid-season when T. kanzawai densities were high with hot weather. Amblyseius eharai and A. kokufuensis occured only in early season, but A. terminalis density increased from mid-season and lasted to late-season. The predacious mite complex regulated the density of T. kanzawai approximately under 8 mites per leaf. Tentatively concluding, T. vulgaris is an adaptable predator at lower prey density under cool weather condition, and A. womersleyi is effective predator at higher prey density under hot weather condition. Further, the biological control strategies of spider mites in Korean orchards were discussed based on the predacious mite complex.

• Korean journal of applied entomology
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• v.36 no.3
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• pp.231-236
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• 1997

Arthropods of 3 Classes, 19 Orders and 58 Families were collected by the enticing band from the trunk of apple trees in winter in Kyongbuk province. The two spotted spider mite, Tetranychu.v urricae Koch, was dominant species with 53.0%, followed by Eriosomtr lanigerutn Hausmann. 16.7%. Oribatida 13.3% and Collembola 9.3%. Of those, herbivores were majority, followed by some decomposers and few natural enemies. Arthropods of 2 Classes, 12 Orders and 17 Families were observed from the fallen leaves. T. urric,ae 63.1% was dominant, followed by Collembola 13.797~ and other Arthropods. While 2 Classes, 9 Orders and 18 Families were investigated from the soil of apple orchards. They were collembola 37.9%. Oribatida 34.476, T. urticae Ih.l% and others in few numbers. Decomposers were majority, followed by herbivores and few natural enemies.

• Korean journal of applied entomology
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• v.35 no.3
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• pp.243-248
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• 1996

This study was conducted to select the acaricides selective to H. axyridis and examine the effects on phytophagous mites and natural enemies after application of selected acaricides in the apple orchard. All the acaricides tested were more toxic to T. urticae and P. ulmi than to H. axyridis, and also were more toxic to egg than to the larva and adult of H. myridis. Azocyclotin and fenpropathrin were the highest and lowest selective acaricides to H. axyridk, respectively. The density of phytophagous mites was high affected by frequency of acaricide application. Significant difference in the changes of the density of natural enemies was not be observed according to frequency of acaricide application and kinds of acaricide. Acaricide treatment showed high effect on the population densities of A. womersleyi and Oriur spp., while less effect on Chrysopa spp.