• Korean journal of applied entomology
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• v.61 no.1
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• pp.255-266
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• 2022

This study was conducted to examine the effects of grass vegetation (W: manual weeding, NW: herbicide sprays) and pyrethroid spray (P: pyrethroid spray, NP: no pyrethroid spray) on the population dynamics of Panonychus citri and natural enemies in citrus orchards. Two essential hypothesis were made to test the population dynamics: 1) weed planting promotes natural enemies by offering habitat and alternative food sources, resulting in the reduction of P. citri populations, and 2) pyrethroid spray removes natural enemies by its non-selective toxicity, resulting in the increasement of P. citri populations. The observed natural enemy populations (mainly Phytoseiids and Agistemus sp.) were not different largely from the expected values in the hypothesis, which assumes more abundant natural enemies in weeds and no pyrethroid plots. Although some discrepancy was occurred in NW+NP and W+NP plots in 2011, the observed values were almost same with expected values in 2012. In overall, pesticide effect was strongly significant and pyrthroids removed largely natural enemies. Although habitat (weeds) effect showed a conflict result, natural enemy population increased in plots allowing weed growth, when considering the increased autumn population relatively compared to that of spring-summer population. The decreased abnormal P. citri populations in pyrethroid plots could be explained under the assumption of a strong repellent behavior of P. citri to the pyrethroids.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.229-238
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• 2022

Animal pollination is an important ecosystem service provided mostly by diverse insect groups such as bees and hover flies. Maintaining agricultural productivity and securing the nutritional balance are closely tied to human wellbeing. This study aimed to estimate the pollination dependent food production in Korean agricultural system. Crop production data were obtained from Korean statistical information service (KOSIS) data of 2015. By implementing pollination dependency, crop production and market price, contribution of insect pollination to crop production increase were estimated from total 71 crops including 12 cereals, 19 fruits, 18 field vegetables, 13 greenhouse vegetables and 9 specialty crops. Mean pollination dependency of all crops were 29.2% and it was higher on fruits, specialty crops and greenhouse vegetables as well, but low (7.5%) in cereal crops. Pollination dependent (PD) production was estimated as 17.8% of total agricultural crop production with the economic value of 6,850 (6,508-7,193) billion won. Especially, PD production of greenhouse vegetables accounted 49.2% followed by fruits of 42.9%. Even specialty crop also showed higher PD production (35.9%). It was obvious that pollination is the vital service for agricultural production as well as nutritional security in Korea. Further protection and enhancing the pollination service were discussed with integrated pollinator-pest management (IPPM) strategies.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.173-195
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• 2022

Like vertebrates, insects synthesize various eicosanoids after the committed catalytic step of phospholipase A₂ (PLA₂). However, the subsequent biosynthetic steps exhibit some deviation from those of vertebrates. Due to little composition of arachidonic acid in insect phospholipids, PLA₂ releases linoleic acid, which is another polyunsaturated fatty acid and relatively rich in insect phospholipids, to synthesize arachidonic acid via chain extension and desaturation. Resulting arachidonic acid is then oxygenated into a prostaglandin (PG), PGH₂, by a specific peroxidase called peroxynectin, but not by cyclooxygenase. PGH₂ is then isomerized to various PGs such as PGA₂, PGD₂, PGE₂, PGI₂, and a thromboxane (TXB₂). All four epoxyeicosatrienoic acids such as 5,6-EET, 8,9-EET, 11,12-EET, and 14,15-EET are also synthesized from arachidonic acid by oxygenation of vertebrate types of monooxygenases. However, the other type of eicosanoids called leukotrienes are found in insect tissues but their synthetic pathway is unclear. Eicosanoids mediate various insect physiological processes such as metabolism, excretion, immunity, and reproduction. Thus, identification of novel compounds interrupting eicosanoid biosynthesis would be a novel approach to develop insecticides. This review focuses on PGs and their immune mediation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.5
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• pp.383-393
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• 1991

Lodging of rice plant is the most important damage by unfavourable weather conditions in rice cultivation. High levels of nitrogen application and growing of Japonica rice variety is one factor to increase the lodging damage. Lodging of rice plant decreasing grain yield; 34% at milky. 21% at dough. 20% at yellow stage. decreasing grain Quality. increasing green rice. and increasing labor cost to harvest. To decrease lodging damage. the lodging resistant varieties will be selected and cultural practices such as amount and time of nitrogen application. planting density. water management. and disease and pest control methods have to be study for the short and strong culm. and good rooting system. Also. application methods such amount and time of plant growth regulators and new types of chemicals will be develop for the reducing lodging of rice plant. To decrease the lodging damage in direct seeding cultivation. first identifying the differences of lodging mechanisms between hand transplanting and direct seeding, second establish the suitable direct seeding methods such as seedling establishement. fertilization. and water menagement.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.3
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• pp.180-183
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• 2001

This study was conducted to find out the effect of ripened grain and rice quality by the breeding of rice dust mite (Steneotarsonemus spinki). Growth temperature of sample (Suwon 441 and Ilpumbyeo) was maintained from 22$^{\circ}C$ (during night) to 26$^{\circ}C$ (during day) in a controlled phytotron. Plant hight and number of panicle could not showed the difference by the discoloration degree of leaf sheath. But number of spikelet was reduced affected by discoloration degree of leaf sheath. Ratio discoloration of grain was increased according to circumstances more discoloration degree of leaf sheath in Suwon 441 then Ilpumbyeo. The perfect rice grain was observed to similar Suwon 441 and Ilpumbyeo in the IV degree of ratio discoloration of grain, but less Suwon 441 than Ilpumbyeo in III and II, in such a case comparison between coloration and discoloration.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.2
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• pp.243-249
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• 1996

To formalize the mechanization technique so as to build up competitiveness on the international market, a detail survey of a 104ha size rice farm, was made. And calculated to find out how many machine of each calibre are needed. It was found that he needed : 3 farm tractors, 3 combines, 4 grain dryers, 1 speed sprayer, 100 man days of labor for sowing, application of fertilizer and herbicide, respectively. And also needed 150 man days for combine harvesting and 60 man days for disease and pest control. It was found also that well timed harvesting is critically needed to keep rice quality. Because, in case when harvesting machine was beakdown to make harvesting time extended, then the quality drops down very much and also the farm income fall very much. Therefore, it is recommended that the amount of machine needed should be prepared and they should be well maintained so that harvest be completed in time.

• Korean journal of applied entomology
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• v.61 no.4
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• pp.529-537
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• 2022

The susceptibilities of five insecticides to the larvae of Spoladea recurvalis, a major pest of spinach, were evaluated. Lufenuron EC, chromafenozide EC, chlorantraniliprole WP, tebufenozide WP, and pyridalyl EW showed 90% or more insecticidal activity at dilution concentrations of 2 (12.5 ppm), 4 (12.5 ppm), 8 (2.5 ppm), 4 (20.0 ppm), and 8 (12.5 ppm), respectively. At their recommended concentrations, Chromafenozide EC, chlorantraniliprole WP, tebufenozide WP, and pyridalyl EW showed very high insecticidal activity of 98.3%, 100%, 95.0%, and 100%, respectively, after 72 h on S. recurvalis larvae exposed after 7 days of treatment. Field tests at two spinach greenhouses in Hwaseong and Yeoncheon showed a high control effect of over 90% after 7 days of treatment in both areas. In addition, the insecticides can be used as exclusive agents for S. recurvalis that occurs in spinach, as there is no phytotoxicity even at double doses.

• Korean journal of applied entomology
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• v.61 no.4
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• pp.563-575
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• 2022

Maruca vitrata is one of important pests in leguminous crops, especially red bean. We investigated the effects of temperature on development of each life stage, adult longevity and fecundity of M. vitrata for understanding the biological characteristics of the insect species at eight constant temperatures of 13, 16, 19, 22, 25, 28, 31, and 34℃. Eggs hatched successfully at all temperature subjected and larvae successfully developed to the adult stage from 16℃ to 31℃. The developmental period of egg decreased up to 31℃ and after then increased. The developmental period of larva and pupa, and adult longevity of M. vitrata decreased with increasing temperature. Lower and higher threshold temperature (TL and TH) were calculated by the Lobry-Rosso-Flandrois (LRF) and Sharpe-Schoolfield-Ikemoto (SSI) models. The lower developmental threshold (LDT) and thermal constant (K) from egg hatching to adult emergence of M. vitrata were estimated by linear regression as 12.8℃ and 280.8DD, respectively. TL and TH from egg hatching to adult emergence using SSI model were 14.2℃ and 31.9℃. Thermal windows, i.e., the range in temperature between the minimum and maximum rate of development, of M. vitrata was 17.7℃. In addition, we constructed the oviposition models of adult, using the investigated adult traits including survival, longevity, oviposition period and fecundity. Temperature-dependent development models and adult oviposition models will be helpful to understand the population dynamics of M vitrata and to establish the strategy of integrated pest management in legume crops.

• Korean journal of applied entomology
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• v.61 no.4
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• pp.577-590
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• 2022

Ostrinia scapulalis is one of important pests in leguminous crops, especially red bean. In order to understand the biological characteristics of the insect, we investigated the effects of temperature on development of each life stage, adult longevity and fecundity of O. scapulalis at eleven constant temperatures of 7, 10, 13, 16, 19, 22, 25, 28, 31, 34, and 36℃. Eggs and larvae successfully developed next life stage at most temperature subjected except 7, 10 and 13℃. The developmental period of egg, larva and pupa decreased as temperature increased. Lower and higher threshold temperature (TL and TH) were calculated by the Lobry-Rosso-Flandrois (LRF) and Sharpe-Schoolfield-Ikemoto (SSI) models. The lower developmental threshold (LDT) and thermal constant (K) from egg hatching to adult emergence of O. scapulalis were estimated by linear regression as 13.5℃ and 384.5DD, respectively. TL and TH from egg hatching to adult emergence using SSI model were 19.4℃ and 39.8℃. Thermal windows, i.e., the range in temperature between the minimum and maximum rate of development, of O. scapulalis was 20.4℃. Adults produced viable eggs at the temperature range between 16℃ and 34℃, and showed a maximum number, ca. 416 offsprings, at 25℃. Adult models including aging rate, age-specific survival rate, age-specific cumulative oviposition, and temperature-dependent fecundity were constructed, using the temperature-dependent adult traits. Temperature-dependent development models and adult oviposition models will be useful components to understand the population dynamics of O. scapulalis and will be expected using a basic data for establishing the strategy of integrated pest management in leguminous crops.

• Korean journal of applied entomology
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• v.61 no.3
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• pp.435-447
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• 2022

The soybean podborer, Matsumuraeses falcana (Lepidoptera: Tortricidae), is one of important pests in soybean crop. In the purpose of forecasting population dynamics of M. falcana, we investigated the effects of temperature on development of each life stage, adult longevity and fecundity of Matsumuraeses falcana at seven constant temperatures of 10, 13, 19, 22, 25, 28, and 31℃. Eggs hatched successfully at all temperature subjected. M. falcana developed from egg hatching to adult emergence at the tested temperatures except 10, 13, and 31℃. The developmental period of each life stage and adult longevity of M. falcana decreased as temperature increased. The lower developmental threshold (LDT) and thermal constant (K) from egg hatching to adult emergence of M. falcana were estimated by linear regression as 10.2℃ and 492.04DD, respectively. Lower and higher threshold temperature (TL and TH) were calculated by the Lobry-Rosso-Flandrois (LRF) and Sharpe-Schoolfield-Ikemoto (SSI) models. TL and TH from egg hatching to adult emergence using SSI model were 16.7℃ and 29.1℃. Thermal windows, i.e., the range in temperature between the minimum and maximum rate of development, of M. falcana was 12.4℃. We constructed the adult oviposition model of M. falcana using adult survivorship and fecundity. Temperature-dependent immature development and adult oviposition models will help constructing the population model of M. falcana and developing the strategies of integrated pest management in soybean fields.