• Korean journal of applied entomology
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• v.58 no.4
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• pp.341-345
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• 2019

Ethyl formate (EF) is a rapid kill, environmentally safe, and low mammalian toxicity fumigant, registered to disinfest quarantine insect pests from imported agricultural products. A new concept for controlling insect pests of agricultural crops was tested in a fumigation chamber with EF. Control efficacy of and phyto-toxicity due to EF fumigation were evaluated against four pests (Thrips palmi, Bemisia tabaci, Myzus persicae, and Tetranychus urticae) and on seedlings of four fruit vegetables (FVs; yellow melon, cucumber, tomato, and pepper). Ethyl formate fumigation at a dose of 1.5 g m^-3 for 12 h produced >93.3% mortality in T. palmi, B. tabaci, and M. persicae. However, T. urticae was tolerant to fumigation, showing only 20% mortality at 2.0 g m^-3. In terms of concentration × time (CT) products, at least 8.9 g·h m^-3 CT at 20 ± 1.5℃ was needed to achieve > 90% mortality against the three susceptible insect pests. Fumigation at 1.5 g m^-3 for 12 h caused no phyto-toxicity to any of the four FV seedlings. Ethyl formate application, as a new disinfestation method in greenhouses, could be an alternative to reduce the use of conventional insecticides. However, further studies are needed to determine the efficacy of this method at different pest developmental stages and in different greenhouse environments. Additionally, research is needed to elucidate the phyto-toxicity of EF application at different growing stages of a wide variety of crops.

• 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.33 no.4
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• pp.230-236
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• 1994

Dicofol susceptible two-spotted spider mite(S) which was selected by 150 times of dicofol treatment showed 27 5-fold increase in resistance as compared to S strain. Inheritance of resistance and crossresistance in selected strain($R_d$) were investigated. There were differences oi susceptibility in the dicofol concentmtion-moltaliity relationships between $F_1$ progenies (R♀, XS♂, R♂, XS♀) obtained from reciprocal cross with the S strain and $R_d$, strain. Degree of dominance of the $F_1$ progenies (R♀, XS♂, R♂, XS♀) were -0.29 and -0.72 in adult females and -0.42 and -0.93 in adult males, respectively. These results suggest that inheritance of dicofol resistance is controlled by an incomplete recessive. $R_d$ strain exhibited a high level of cross resistance to amitraz, and also showed cross resistance to pyrethrotd acaricides, acrinathrin and bifenthnn. $R_d$ strain showed non-cross reslstancz to abamectin, chlolfenson, clofentezine, cyhexatm, fenbutatin oxlde, fenpyroximate, hexythiazox, monocrotophos, propargite and tetradifon, but negatively correlated cross-resistance to azocyclotin and fenbutatin oxide belonging to tin acaricides.

• Korean journal of applied entomology
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• v.47 no.1
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• pp.59-64
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• 2008

Insecticidal activity of 20 plant species against adults of Myzus persicae, female adults of Tetranychus urticae, and $2^{nd}\;or\;3^{rd}$ instar larvae of Plutella xylostella was evaluated in this study. Thirteen plant extracts showed over 80% acaricidal activity to T. urticae at the concentration of 1 %, while Capsicum annuum (hot-pepper seed), Inula helenium, and Acorus calamus revealed 82.8-86.2% acaricidal activities at 0.5%. Insecticidal activities of the plant extracts to M. persicae and P. xylostella were relatively low compare to the mite. Among the plant extracts, C. anuum and Brassica juncea revealed 48.6% and 42.9% respectively insecticidal activities to the aphid at the concentration of 0.5%. Extracts of C. anuum and Jeffersonia dubia provided 55% and 50% insecticidal activity against P. xylostella at 1%. And, the highest antifeeding activity of the insect was observed in the J. dubia extract as 79.4%. Results indicated that some plant extracts including hot pepper seed could be used as potential botanical pesticides for organic farming.

• Korean journal of applied entomology
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• v.28 no.4
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• pp.237-243
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• 1989

These studies were conducted to investigate the development of chemical resistance in two-spotted spider mite (Tetranychus urticae Koch) through alternate selection for a given period of time with four acaricides including ethion of organophophours compound, dicofol of organo-chlorine compound, cyhexatin of organo-tin compound, and biphenthrin of synthetic pyrethroid compound; and to examine multiple-resistance among the acaricides to the selected populations. The development levels of chemical resistance in the two-spotted spider mite were greatly varied under alternate selection with the different chemical-group combination of four acaricides. Resistant levels of the ethion/dicofol-selected population at 13th-13th generation showed 49.4-fold resistance to ethion and 18.1-fold to dicofol; the ethion/cyhexatin-selected population at 9th-9th generation exhibited 28.1-fold to ethion and 5-fold to cyhexatin; the ethion/biphenthrin-selectd population at 10th-10th generation revealed 39.8-fold to ethion and 19.2-fold to biphenthrin. However, the dicofol/cyhexatin-selected population at 9th-9th generation showed 11.3-fold to dicofol and 4.9-fold to cyhexatin, and the dicofol/biphenthrin-selected population at 12th-12th generation exhibited 11.2-fold to dicofol and 9.4- fold to biphenthrin, while the cyhexatin/biphenthrin-selected population at 9th-9th generation revealed 3.7-fold to cyhexatin and 7.7-fold to biphenthrin. In case of alternate selection, the ehtion/dicofol-selected population revealed moderate multiple-resistance level to biphenthrin. The ethion/cyhexatin-selected and the ethion/biphenthrin-selected populations showed low mutiple-resistance level to biphenthrin and dicofol, respectively. However, the dicofol/cyhexatin-selected, the dicofol/biphenthrin-selected and the cyhexatin/biphenthrin-selected populations exhibited high multiple-resistance level to ethion.

• Korean Journal of Environmental Biology
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• v.34 no.1
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• pp.56-62
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• 2016

Pest population density models are very important to monitor the initial occurrence and to understand the continuous fluctuation pattern of pest in pest management. This is one of the major issues in agriculture because these predictions make pesticides more effective and environmental impact of pesticides less. In this study, we combined and predicted the mortality change of pest caused by pesticides with temperature change and population dynamic model. Sensitive strain of two-spotted spider mite (Tetranychus urticae Koch) with kidney bean leaf as host was exposed to mixed acaricide, Acrinathrin-Spiromesifen and organotin acaricide, Azocyclotin, at 20, 25, 30, and $35^{\circ}C$, respectively. There was significant difference in mortality of T. urticae among pesticides and temperatures. We used DYMEX to simulate population density of T. urticae and predicted that the initial management time and number of chemical control would be changed in the future with climate change. There would be implications for strategies for pest management and selection process of pesticide in the future corresponding climate change.

• 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.49 no.4
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• pp.401-407
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• 2010

Daily predation of female/male O. sauteri during nymphal development were 4.2/3.9, 11.4/9.5, 14.3/10.8, and 14.7/12.5 at 17,22,27, and $32^{\circ}C$, respectively, and consumed 14.3/10.8 thrips, 7.5/7.2 aphids, 45.9/38.8 mites at $27^{\circ}C$, respectively. Adult females ate 42.8 thrips daily during preoviposition period and 63.2 thrips during oviposition period at $27^{\circ}C$. Predation by O. sauteri on F. occidentalis increased as the density of F. occidentalis increased. However, the rate of increase gradually lessened, resembling a Holling's type II functional response. The attack rate of adult female is higher than that of the 5th nymph. Adult female and 5th nymph of O. sauteri appeared to prefer 2nd larva of F. occidentalis.

• The Korean Journal of Pesticide Science
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• v.9 no.4
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• pp.380-390
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• 2005

This study was carried out for looking into the status of susceptibility of vinyl house insect pests to insecticides. The Thrips (Thrips palmi and Frankliniela occidentalis), Mites (Tetranychus urticae), Aphids (Aphis gossypii) and Whitefly (Trialeurodes vaporariorum) were captured at various areas where the host crop was being cultivated and the susceptibility level of each pest insect was investigated. The susceptibility of each pest insect varied by insect species and areas where they were caught. The tested insecticides showed good control effect to palm thrips in 2000, but in 2003 showed decrease of effect to them. Western flower thrips showed low susceptibility to neonicotinoids, imidacloprid and thiamethoxam, but high to chlorfenapyr, spinosad, emamectinbenzoate and fipronil. Antibiotic insecticides, abamectin and milbemectin, and chlorfenapyr were very effective on mite control and dicofol still had good effectiveness to it despite of long year use. No aphid species showed resistance to pyrethroid and carbamate insecticides. Relatively new insecticides such as imidacloprid, spinosad, pymetrozine were effective to whitefly, but not were organophosphates, carbamates and pyrethroids.

• Journal of Practical Agriculture & Fisheries Research
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• v.22 no.2
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• pp.135-146
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• 2020

In the strawberry cultivation areas and domestic farms, two-spotted spider mites are the most serious pests. It decreases the product yield due to the direct feeding of chlorophyll by the mites resulting in reduced photosynthetic ability of host plant. In this study, a simplified acaricidal effect evaluation system (SAEES) was employed to choose the effective acaricidal products among 10 items based on leaf-dipping bioassay methods. SAEES had the advantage of being able to screen four commercial products with three replications at the same time in the recommended concentration. The susceptible strains (SL_YS) showed a high mortality rate of about 90-100%, whereas the mortality of local strains was differed by each acaricides. It suggests that the acaricide responses of field populations might differ due to spray frequencies and acaricide product. An efficacy index (0.8-1.0) was determined based on the mortality of susceptible strain, which would allow the most effective commercial products to be selected by the range of this index. In summary, SAEES will enable the selection of effective commercial products and contribute to increasing control against T. urticae in strawberries.