• The Korean Journal of Soil Zoology
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• v.6 no.1_2
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• pp.17-20
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• 2001

The preference ratio of spider mites (Tetranychus urticae and T. kanrawai) on the chrysanthemum, Gypsophila paniculata, Carnation and Rose was high, but Lilium, Calla, Startis and Gladiolus was low. Field adaptability of Tetranychus kanzawai on the chrysanthemum variety was high in Yellowment variety but low in five other varieties. That of T. urticae line was high on 9818-1, 9819-5, 9820-6 chrysanthemum lines but low on other six lines . Preference ratio of T. urticae was 82.8% higher on upper than on lower surfaces in the field.

• Korean journal of applied entomology
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• v.36 no.3
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• pp.237-242
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• 1997

Comparative studies on suppression possibility with three phytoseiid mite species (An.thly,seiu,sw omersleyi Schicha. A. ,fidIrrc~i.Gs arman and T\ulcornerphlorlrotiiu.s oc~c~idetitaliNs esbit) to the two-spotted spider mite (Te~trrrt~yc.Iir~l~l\ulcorner.i\c .(re Kwh) on kidney bean leaves in field and greenhouse were carried out. In the field experiments with the initial prey -predator ratio of 4 : 1. I0 : I and 20: I . A. ,firllrrcis suppressed successfully the prey populations at all three ratios 17 days after the initial infestation. A. wornc,r-;leyi \uppressed the prey population only at the ratio of 4 : 1, while T. oc~c~ideritcr1iw.s as unable to suppress the prey population at all tested ratios. In the greenhouse experiments with the initial prey-predator ratio of 10: 1, A. jil1ltrci.s could suppress the prey population continuously during the infestation period. A. ~~otnc~r,slceoyuil d suppress the prey population for 13 days after the initial infestation, while T. occie1mttrli.s could suppress the prey population for 8 - 23 days after the initial infestation.

• Korean journal of applied entomology
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• v.43 no.1
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• pp.71-79
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• 2004

Toxicities of 42 pesticides (13 acaricides, 13 insecticides, 13 fungicides and 3 adjuvants) commonly used to control rose insect, mite, and disease pests were evaluated to the two-spotted spider mite, Tetranychus urticae egg and adult, and its predator Phytoseiulus persimilis egg, nymph and adult at the recommended concentration. The effect of density suppression of T urticae by predatory mite and pesticide mixture on the rose in the greenhouses was also investigated. Among 13 acaricides tested, acequinocyl, bifenazate, fenbutatin oxide and spirodiclofen showed much less toxicity to P. persimilis than to T urticae. Among insecticides, acetamiprid, imidacloprid, spinosad, thiamethoxam and acetamiprid＋etofenprox showed low toxicity to P. persimilis. and T ruticae. Among 13 fungicides, azoxystrobin, kresoxim-methyl, myclobutanil, nuarimol, triadimefon, triflumizole and oxadixyl＋mancozeb had a negligible effect on P. persimilis and T. urticae. Among three adjuvants, cover and siloxane expressed high toxicity, while spreader showed very low toxicity to P. Persimilis. In the greenhouses experiments, the density of T urticae before treatment was 65.3 mites per leaf. However, their density after release about 30 predatory mites per rose abruptly decreased from 3.8 mites at 11th day to zero mite at 20th day. During survey periods, four treatments of fungicides (kresoxim-methyl, myclobutanil, nuarimol, triflumizole) for the control of Sphaerotheca pannosa and one treatment of insecticide (spinosad) the control of Frankliniella occidentalis were applied, and these treatments had no the pesticides had no effect on the predatory mite density. It may be suggested from these results that four acaricides, five insecticides, seven fungicides, and one adjuvant could be incorporated into the integrated T. urticae management system with P. persimilis on rose cultivation.

• Korean journal of applied entomology
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• v.45 no.2 s.143
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• pp.173-177
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• 2006

Biological control of Tetranychus urticae by Phytoseiulus persimilis was observed in eggp1ant greenhouse fur spring and autumn season culture. Tetranychus urticae was controlled to low density of less than 1 mite from June 24 after p. persimilis were released 3 times at rate of 10 per plant on June 1, 11, and 18, 2004 in spring season experiment. The population of Tetranychus urticae was also less than 1 mite per eggp1ant leaf from September 1 to October 22 after three times releases of 10 P. persimilis in autumn season experiment. In Phytoseiulus persimilis released plot, the percentage of leaves with T. urticae adults and nymphs were 8.6$\sim$13.3% and 5% or less in spring and autumn season experiment. The density of T urticae was from 1 to 2 on leaves with T urticae adults and nymphs.

• 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.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.35 no.2
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• pp.164-172
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• 1996

The comparative toxicity of abamectin to the predatory mite, Amblyseius womersleyi Schicha and the spider mites, Tetranychus urticae Koch and T. kanzawai Kishida was evaluated by leaf disc method. Abamectin was much less toxic to A. womersleyi than to the spider mites. Although survival rate of adult females of A. womersleyi tended to decrease with increasing abamectin concentration, 8-78% of predators remained alive at concentrations of 0.38-6 ppm. Likewise, reproduction was significantly reduced with increasing abamectin concentration. Abamectin neither affect the hatch of A. womersleyi eggs nor the development of surviving immature predators. Survival of immature predators decreased with increasing abamectin concentration. However, 42-90% of immature predators reached adulthood at 0.38-3 ppm. Adult female predators survived on a diet of spider mites intoxicated with abamectin, although their fecundity and the sex-ratio of the progeny were significantly affected. Abamectin at selective sublethal concentrations (0.38-0.75 ppm) could he of value in adjusting predatorlprey ratios in integrated management of T. urticae and T. kanzawai.

• Korean journal of applied entomology
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• v.35 no.3
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• pp.266-272
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• 1996

The selective tox\ulcornercity of fenpyroximate to the predatory mite Amblyseius womersleyi and the twospotted spider mite Tetranychus urticae was evaluated. Adult females and eggs of both species were placed on bean leaf dis~sd ipped in several concentrations of fenpyroximate. Fenpyroximate was much less toxic to A. womersleyi than to T. urticae. Although the survival of adult females of A. womersleyi tended to decrease with increasing fenpyroximate concentration, 58-74% of predators remained alive at concentrations of 6.25-50 ppm. However, reproduction of predators was not significantly reduced at any of the concentrations tested. At 6.25-50 ppm, 32-40% of twospotted spider mite adult females survived but all survivors were immobilized. Moreover, reproduction of twospotted spider mites was reduced with increasing fenpyroximate concentration. Fenpyroximate did not affect the hatch of A. womersleyi eggs or the development of immature predators. Although survival of immature predators decreased with increasing fenpyroximate concentration, 16-48% of immature predators reached adulthood at 6.25-50 ppm. However, all immature spider mites failed to develop to adulthood at 6.25-50 ppm. Adult female predators survived on a diet of twospotted spider mites intoxicated with fenpyroximate, and their fecundity and sex-ratio of the progeny were not substantially affected. Fenpyroximate at selective sublethal concentrations (6.25-12.5 ppm), therefore, could be of value in adjusting predatorlprey ratio in integrated management of twospotted spider mites.

• Journal of Sericultural and Entomological Science
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• v.52 no.2
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• pp.155-158
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• 2014

Biological control of Tetranychus urticae by Phytoseiulus persimilis was carried out on tropical plant (Erythrina caffra, Phytolacca dioica) from April to July. Experiments were conducted at Tropical Plant Resources Research Center of Korea National Arboretum. Phytoseiulus persimilis (200 individual/tree) was released once (12. May) to control Tetranychus urticae. We measured the density of leaf-feeding T. urticae at intervals of approximately 2weeks after introducing P. persimilis. The densities of T. urticae were suppressed 10%, in Erythrina caffra and 49% in Phytolacca dioicas after 2 weeks introducing them.

• Korean Journal of Organic Agriculture
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• v.14 no.3
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• pp.315-323
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• 2006

The potential of the predatory mite Phytoseiulus persimilis (Acarina : Phytoseiidae) to control two spotted spider mite Tetranychus urticae (Acarina : Tetranychidae) was investigated on sustainable strawberry fields in Jeonnam area. The density of T. urticae increased from 4th and 7th weeks after single and two timings release P. persimilis, respectively. On the three timings of release plot, number(density) of T. urticae on a leaf maintained fewer than 10 during the 15 weeks after release. In the 1,000 release of P. persimilis per $100m^2$ plot, P. persimilis could not suppress T. urticae. In the 2,000 release plot, P. persimilis could suppress T. urticae with low density which was the similar in the 3,000 release plot. Two-spotted spider mite, T. urticae, occurred from late March and increased density in Hampyeong area. In the P. persimilis released field, T. urticae inhibited continuously after release. In Boseong area, density of P. persimilis increased 50 per 10 leaves through increasing of T. urticae. Percent of occurrence of T. urticae showed high $10.5{\sim}75.5%$ in none-release predatory mite but not high in release treatment. T. urticae on sustainable strawberry field could be inhibited by P. persimilis.