• The Korean Journal of Pesticide Science
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• v.8 no.1
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• pp.54-62
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• 2004

The selective toxicity of spirodiclofen and fluacrypyrim+tetradifon to the predatory mite, Phytoseiulus persimilis and the tea red spider mite, Tetranychus kanzawai was evaluated. The bean leaf discs with adult females or eggs of both species were sprayed with several concentrations of spirodiclofen or fluacrypyrim+tetradifon. Spirodiclofen and fluacrypyrim+tetradifon were much less toxic to P. persimilis than to T. kanzawai. Although the survival rate of adult females of P. persimilis tended to decrease with increasing concentrations of spirodiclofen, 92-68% of predators survived at concentrations of 22.5-180 ppm. Likewise, reproduction was reduced with increasing spirodiclofen concentration. Spirodiclofen did not affect the hatch of P. persimilis eggs. Survival of immature predators decreased with increasing spirodiclofen concentration, however, 88-20% of immature predators reached adulthood at 22.5-90 ppm. In the case of fluacrypyrim+tetradifon, the survival rate of adult females of P. persimilis tended to decrease with increasing concentrations of fluacrypyrim+tetradifon. However, 94-72% of predators remained alive at concentrations of 22.5-180 ppm. Likewise, reproduction was reduced with increasing fluacrypyrim+tetradifon concentration. Fluracypyrim+tetradifon did not affect the hatch of P. persimilis eggs. Survival of immature predators decreased with increasing fluacrypyrim+tetradifon concentration, however, 100-86% of immature predators reached adulthood at 22.5-180 ppm. Based on the results, spirodiclofen and fluacrypyrim+tetradifon appeared to be promising candidates for use in integrated mite management programs where P. persimilis is the major natural enemy.

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.448-453
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• 2013

We investigated the occurrence of major pests, 4 species of moths (Grapholita dimorpha Busck, Carposina sasakii Matsumura, Archips breviplicanus Walsingham, Adoxophyes orana Fischer von Roslerstamm), apple aphid (Aphis spiraecola Patch), two spotted spider mite (Tetranychus urticae Koch) and parasitoids in pear orchard with hairy vetch and cutting weeds in Yesan, Chungnam province during the flowering season and summer depression season of hairy vetch, in 2012 and 2013. The occurrence of 4 species of moths in hairy vetch plot and cutting weeds (major is finger grass, Digitaria sanguinalis, 80%) were little different but in case of apple aphid, the density in hairy vetch plot was just 95 aphids per stem at 20th June but low after then. The density of two spotted spider mite on pear leaf in hairy vetch plot was lower than in cutting weeds plot significantly. The number of parasitoids collected in hairy vetch plot during flowering season (May and June) were 398 and 798 in 2012 and 2013, respectively. The number of parasitoids collected in hairy vetch plot during summer depression season (July and August) were 114 and 172, respectively. But in cutting weeds plot, 9 and 22 in May and June, 8 and 5 in July and August. We didn't know either hairy vetch in pear orchard affected the occurrence of 4 species of moths, apple aphid and two spotted spider mite or not but was acted to be favorable for wasps, the natural enemies on the contrary. The improvement of chemical control systems through the selection of low chemicals to natural enemies with cover and green manure plants would turn effective pest management into a possibility.

• Korean journal of applied entomology
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• v.35 no.3
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• pp.232-237
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• 1996

Toxicity of 5 acaricides, 4 insecticides. and 6 fungicides to the twospotted spider mite, Tetranychus urticae Koch, and its predator Amblyseius womersleyi Schicha was assessed in a laboratory using a leaf disk bioassay. Dicofol was equally very toxic to aduly females of T. urticae and A. womersleyi, and caused 46% and 40% mortality of eggs of those two species, respectively. Adult females of A. womersleyi dipped in Abamectin solution showed low mortality(16.6%), while all T. urticae females died within 24 hours after dipping. Three ovicidal acaricides (Tetradifon, Clofentezine, and Hexythiazox) showed no mortality of predator eggs, but more than 90% mortality of T. urticae eggs. Four insecticides (Teflubenzuron, Triflumuron, Diflubenzuron, and Imidacloprid) and three fungicides (Propineb, Fenarimol, and Polyoxin-B captan) were non toxic to the A. womersleyi adult females. The other fungicides (Chlorothalonil, Nuarimol.Mancozeb, and Folpet) were a little toxic to adult females of the predator, showing$\leq$23.3% mortality, It may be suggested from these results that 4 insecticides, 4 acaricides, and 6 fungicides described could be incorporated into the integrated pest management system with A. womersleyi in apple orchard.

• Journal of Bio-Environment Control
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• v.9 no.3
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• pp.179-184
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• 2000

This study was conducted to improve control system of insect pests, especially western flower thrips, Frankliniella occidentalis, and two-spotted spider mites, Tetreanychus urticae, of rose greenhouses. Density of thrips was relatively higher in yellow flowers than in pink or redflowers, while there was no difference in density of two-spotted spider mites by flower colors. In pest control by an automatic monorail sprayer, 89% labor and 18.2% chemical savings, as compared to the conventional high pressure spray method, were achieved without lowering the pest control effectiveness. By using an adhesive agent in combination with acaricide, adhesion of chemical to crops increased by 25% and control effect on two-spotted spider mites increased by 20.5% as compared acaricide spray alone.

• Proceedings of the Korean Statistical Society Conference
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• 2003.05a
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• pp.69-74
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• 2003

The estimation of pest density is a prime concern of Integrated Pest Management (IPM) because the success of artificial intervention such as spraying pestcides or natural enemies depends on pest density. Also, the spatial pattern of pest population within plants or plots has been studies in various ways. In this study, we applied generalized linear mixed model to Tetranychus urticae Koch , two-spotted spider mite count in glasshouse grown roses. For this analysis, the subject-specific as well as pupulation-averaged approaches are used.

• 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.

• Korean journal of applied entomology
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• v.42 no.3
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• pp.249-255
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• 2003

These studies were carried out to investigate fumigant, contact toxicity and repellency effects of 34 terpenes against acaricide susceptible the two-spotted spider mite, Tetranychus urticae. In addition, the efficacy was also tested against two acaricide-resistant strains. Two terpenes, isosafrole and safrole showed fumigant toxicity of 98.4%, at 10${\mu}\ell$/1 (air) concentration. LD$\_$50/ values of these two terpenes were 2.6${\mu}\ell$/1 and 4.3${\mu}\ell$l/1, respectively. Most terpenes showed low or no contact toxicity, except isosafrole showing 60.2% mortality against eggs. Hexanoic acid and limonene showed repellency effects of 79.1%, 87.8%, respectively, to the susceptible strain at concentration of 1,000 ppm in the lab conditions. Hexanoic acid (1,000 ppm) showed repellency effected of 77.8% and 83.3% to fenpropathrin and pyridaben resistant strains, respectively. However, limonene showed no repellency to the two resistant strains.

• Korean journal of applied entomology
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• v.34 no.1
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• pp.61-64
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• 1995

Stability of resistance of the two-spotted spider mite (Tetranychus urticae) to dicofol was investigated. Resistance level (23.0-fold) of adult females to dicofol was kept up to 1 year without selection by dicofol, but was decreased to 15.8-, 10.7-fold after 2 and 3 years, respectively. Susceptibility of adult females obtained from reciprocal crosses $(R_{female}\timesS_{male},R_{male}\times S_{female})$ of the R and S stains to dicofol was declined by the success of generation.

• Korean journal of applied entomology
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• v.31 no.4
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• pp.452-460
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• 1992

To establish the economical and reliable routine bioassay system for developing new insecticidal compounds, effects of leaf-dipping time, application methods, insect species and their developmental stages on susceptibilities of insects to insecticides were studied. The stable insecticidal activity appeared at the dipping time for 30-60 seconds in leaf-dipping method, and the most effective application methods were leaf-dipping method for apterous green peach aphid adults, and third instars of diamond-back moth and tobacco cutworm, whereas seedling+insect spray method for adults or third instars of brown planthoppers. For two-spotted spider mite, leaf-dipping or intact plant spray method was favorable. In the bioassay for chitin synthesis inhibitors, the inoculation of third instars of brown planthopper, diamond-back moth, tobacco cutworm and green peach aphid, and larvae of two-spotted spider mite to the young host plants treated by spray method were adequate bioassay methods.