• The Korean Journal of Pesticide Science
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• v.12 no.3
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• pp.249-255
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• 2008

The comparative toxicity of recommended rates of three acaricides, fluacrypyrim, cyflumetofen and spiromesifen to the predatory mite, Neoseiulus womersleyi and its prey, Tetranychus urticae was bioassayed in the laboratory. Fluacrypyrim and cyflumetofen were much less toxic to adult females of N. womersleyi than to those of T. urticae. Adult female predators treated with these two acaricides produced $88{\sim}93%$ as many eggs as did control females. Fluacrypyrim and cyflumetofen did not affect the hatch of N. womersleyi eggs or the development of surviving immature predators, and $92{\sim}96%$ of immature predators reached adulthood. Spiromesifen at its treated concentration did not significantly affect the survival and reproduction of adult female predators but caused 100% mortality in larvae of N. womersleyi. Adult female predators survived on a diet of spider mites treated with fluacrypyrim and cyflumetofen, and their fecundity was not significantly affected. Moreover, immature predators developed normally on prey treated with these two acaricides. The results indicate that fluacrypyrim and cyflumetofen are promising candidates for use in integrated mite management programs where N womersleyi is the major natural enemy.

• Korean journal of applied entomology
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• v.31 no.1
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• pp.1-6
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• 1992

These studies were carried out to compare toxicological test methods of two spotted spider mite, Tetranychus urticae Koch,; and to investigate relationship between in vivo resistant level of highly acaricide-selected population, and in vitro insensitivity of the AChE in the same population to carbophenothion and ethion. The slide dip method (CV = 8.7%) was of more accuracy and suitability than that of the leaf dip method(CV=12.2%) and leaf disc method (CV= 13.6 %) in determination of the resistant levels of twospotted spider mite to acaricides. The slide dip method also had the advantages of simple treatment with different populations on a slide at the same time, standardization of post-treatement conditions and living plants exclud¬ed from the test. Even though the topical application method(CV =8.1 %) showed high accuracy, it had the demerits of the much time consuming, need of expensive equipment and difficulty of test manipulation. For a limited time, the 22nd successive carbophenothion-selected population of two-spotted spider mite showed 156- and 128-fold resistant levels to carbophenothion and ethion(both alPs), respectively. However, the 24th successive ethion-selected population revealed 64.1- and 65-fold resistant levels to ethion and carbophenothion, respectively. In the inhibition of AChE activity, the carbophenothion-selected population showed 3.3- and 2.7-fold insensitivity in AChE activity to carbophenothion and ethion, respectively. Likewise, the ethion -selected population exhibited 3- and 2.6-fold insensitivity in AChE activity to carbophenothion and ethion, respectively, as compared with that of susceptible population. As a result, a good relation was recognized between in vivo resistance to organophosphorous acaricides and in vitro insensitivity of the AChE to corresponding inhibitors.

• Korean journal of applied entomology
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• v.34 no.4
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• pp.328-333
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• 1995

Susceptibilies of tow-spotted spider mite (Tetranychus urticae Koch) collected at 6 locations were assessed to 15 acaricides. The response to acaricides were almost similar in female adults and eggs. There were considerable difference in susceptibility depending on the acaricide treated and the region from which the population was collected. The population showing resistance ratio of more than 20 with respect to certain acaricide was regarded as a resistant population to the acaricide. The resistant populations in terms of female adult were as follows: Suwon population to azocyclotin, cyhexatin, and fenbutatin-oxide; Taejon population to dicofol and fenbutatin-oxide; Chongju population to dicofoll Chinju populatin to cyhexatin, dicofol, and fenbutatin-oxide. The resistant populations in terms of egg were as follows; Suwon population to bifenthrin, clofentezine, hexythiazox, and tetradifon; Kunwi, Chongju, and Kwangju populations to bifenthrin; Taejon population to amitraz and bifenthrin; Taejon populatin to amitraz and bifenthrin; Chinju population to amitraz, bifenthrin, clofentezine, dicofol, and tetradifon. However, the female adults and eggs of all field populations were susceptible to abamectin, chlorfenson, and fenpyroximate. This tendency was also reported previously in the susceptible strain from laboratory.

• Korean journal of applied entomology
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• v.34 no.3
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• pp.249-255
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• 1995

These experiments were conducted to investigate the life history and the seasonal fluctuation of population density of tea red spider mite, Tetranychus kanzawai Kishida and to observe its natural enemies in the southern area. Under field-cage conditions, tea red spider mite occurred 11~12 generations. The average periods from egg to adult emergence were 8.7~13.1 days in summer and 12.6~24.9 days in spring and autumn. The average longevities of adults were 15.5~21.9 days in summer and 25.1~31.6 days in spring and autumn. The average number of eggs laid per female were 45.1 in summer and 52.6 in spring and autumn. Tea red spider mite population showed two peaks during April-June, and appeared third or forth peak during October-November. The density of all the stages was the lowest in July through August. Tea red spider mites stayed at lower parts of tea plants in March but they moved to upper parts in April though June, and they again moved to lower parts after autumn. Tea red spider mite overwintered as all stages. Adults were the dominant overwintering stage during this stage. The surveyed natural enemies of the tea red spider mite were 7 species including Amblyseius longispinosus (Evans), A. eharai Amitei et Swirski, Anystis baccarun (L), Agistemus fleschneri Summers, Orius sauteri Poppius, Oligota yasumatsui Kistner and Scolothrips sp.

• Korean journal of applied entomology
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• v.35 no.3
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• pp.260-265
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• 1996

A field colony of the two-spotted spider mite, Tetranychus urticae Koch, was selected with tetradifon for 4 mousing whole-plant residual method. This strain showed 371-fold resistance to tetradifon. The log dosehatchability lines of $F_{1}$ eggs(RS cross; Td5female$\times$Smale, and SR cross; Sfemale$\times$Td5male) were closer to the line of the resistant colony than to that of the susceptible. These differences could be due to cytoplasmic inheritance or maternal effect. The estimate of dominance index (D) for the $F_{1}$ eggs of RS cross was 0.998 and that for $F_{1}$ eggs of SR cross was 0.262. This indicates that tetradifon resistance is completely dominant in RS cross and incompletely dominant in SR cross. Td5 strain exhibited high levels of resistance to clofentezine, benzoximate, and chlorfencon, and no cross resistance to fenazaquin, pyridaben, flufenoxuron, tebufenpyrad, and fenothiocarb.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.317-325
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• 2006

According to the preceding survey on insect pests of the green perilla, Perilla frutescens var. japonica HARA, The major pests were Aphis egomae Shinji, Pyrausta panopealis (Walker), Tetranychus urticae Koch, Polyphagotarsonemus lotus Banks, Tetranychus kanzawai Kishida at Guemsan, Chungnam, 2004. Aphis egomae causes nearly 100% injury of the green perilla in uncontrolled green houses. A field study was conducted to estimate economic injury levels (EILs) and control thresholds (CTs) for A. egomae injuring green perilla in green houses. Different densities of A. egomae ranged from 1 to 80 aphids per 100 plants in early inoculation. The mean injurying rate of plant was 2.4% to 40.5% at the end of June at differently inoculated levels. The economic loss time calculated by the ratio of cost managing aphid to market price (C/V) (C: cost managing aphid, V: Market price) in early season (from May to 13. June) was 5.8% and in peak season (from 13. June to 30. June) was 9.3%. Economic injury level in early and peak season was 5.3 aphids per plant and economic injury levels in peak season were 0.6 aphids per plant and 7.6% injured rate of plant. The control thresholds calculated by 80% level of economic injury level in peak season were 0.5aphids per plant and 6.1% injury rate of plant, respectively.

• Korean Journal of Organic Agriculture
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• v.18 no.4
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• pp.573-586
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• 2010

This study was carried out to evaluate characteristics of Chrysanthemum sp. and to bioassay Tetranychus urticae, Nilaparvata lugens, and Aphis gossypii by different extracts part and method. Flower type of Chrysanthemum sp. line was anemone except 0706 line which was pompon. The flowering date was from April to June but 0721 line kept up November. They could overwinter except 0706 line. The Ethanol extracts of 0718 line of flower was high mortality as 63.8% on Tetranychus urticae. Ethanol mixed emulsifier extracts were the highest mortality as 69.4% at 5 days after. Mortality in water extract was lower than in ethanol and ethanol mixed emulsifier extracts. Ethanol mixed emulsifier extracts were higher mortality as 69.4% at 5 days after in 0718 line on Nilaparvata lugens. Mortality in water extract was lower than in ethanol and ethanol mixed emulsifier extracts. On Aphis gossypii, Chrysanthemum flower extracts could decrease the density of aphids in early days but the density of that was increase as time goes by because aphids produce offspring.

• Korean journal of applied entomology
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• v.39 no.1
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• pp.53-58
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• 2000

The effect of NeemAzal-T/S was tested by leaf disk method on fecundity, egg mortality, and preference of twospotted spider mite, Tetranychus urticae and its predator mite, Amblyseius womersleyi in the laboratory. Mortalities of T. urticae and A. womersleyi adults were 97.7% and 20.0%, in 100ppm treatment at 72 h after application, respectively. The mean number of eggs laid per T. urticae female adult were 0.0 and 18.5, and those of A. womersleyi were 1.6 and 2.9 at 100 ppm and 0 ppm concentrations, respectively. Hatchability of T. urticae eggs treated with 50 and 100 ppm were 52.8%, and 2.5%, respectively, and those of A. womersleyi eggs were 100% and 91.3%, respectively. Choice and no-choice tests revealed that T. urticae female preferred to alight and oviposit on untreated bean leaf disk with 13.8 to 18.2 eggs per female. In contrast, A. womersleyi female preferred on treated or untreated bean leaf equally. There was no significant differences in the number of consumption of T. urticae eggs by A. womersleyi on treated and untreated bean leaves, except 200 ppm. These results indicate that NeemAzal-TIS is highly toxic to T. urticae, and is less toxic to A. womersleyi. It may be concluded with these results that NeemAzal-T/S could be incorporated into integrated T. urticae management system.

• Korean journal of applied entomology
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• v.54 no.4
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• pp.351-357
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• 2015

The two-spotted spider mite Tetranychus urticae Koch, overwinters in apple culture areas of apple orchards. The mite overwinters in various places on the apple trees, usually in groups of 5-15 females. Overwintering females were mostly found in bark crevices with the hibernation cocoons of the oriental fruit moth, Grapholita molesta Busck. They were also found in small crevices of the bark, and in pedicels left after fruit harvesting. Furthermore, overwintering females were found on rough bark at the bases of buds and spurs, on small limbs and twigs, and in limb crevices and forks. Empty scales of dead diaspidids and coccids, as well as cocoons of lacewings and mummies of parasitized aphids sporadically found on trees, were found to be less common overwintering sites for females of the two-spotted spider mite. In two successive years, the mortality of overwintering females was very high, reaching approximately 72 and 80%. This could be due to the low temperature of winter season in Korea and the low cold tolerance of the mite.

• Proceedings of the Korean Society of Applied Entomolohy Conference
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• 2001.05a
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• pp.140-140
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• 2001