• The Korean Journal of Pesticide Science
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• v.2 no.1
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• pp.85-90
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• 1998

A series of experiments were carried out to determine the effect of seed dressing application of chemicals on the early occurring rice insect pests. The number of small brown planthopper adults per 3hills in seed-dressing plot of Imidacloprid WS (Im WS) was 1.6 and its control efficacy was over 90%, compared with that of untreated plot. Rice water weevil was observed in the density of 8.8 larvae per 5 hills seed-dressed Im WS plots(showing 95.5% of control efficacy). Control efficacy of Im WS and Im GR against adult weevils lasted for 26 days after treatment and was higher than that of Carbofuran GR. Rates of injured stems by rice stem maggot and injured leaves by rice leaf miner were 3% and 3.7% in Im WS treatment plot respectively. Seed germination rate after seed dressing with recommended dosage (3 g/seed kg) of Im WS was 71 % on the 1st day and increased on 5th day up to that of untreated seed. The residual amount of Im in seed dressing plot was 0.11 ppm in rice roots and 0.05 ppm in leaves on the 40th day after treatment. Residual effect of Im WSI sustained for 50 days with over 95% insecticidal effect for the rice water weevil and over 90% for the brown planthopper. Quantity of the chemical applied in the field was calculated as 0.084 kg a.i./ha in seed dressing and 0.3 kg a.i./ha in seed box treatment, respectively It took 1 hour to treat insecticide by seed dressing, 2.5 hours by seed box applying, and 3.6 hours by water surface releasing per 990 $m^2$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.1
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• pp.74-80
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• 1988

Seasonal population changes in Laodelphax striatellus Fallen (small brown planthopper), percentage of rice black-streaked dwarf virus (RBSDV) viruliferous L. striatellus, and RBSDV infection of 11 corn hybrids were observed at various locations and years. The population size of L. striatellus was relatively small in the middle parts of Korea, but it was much greater in the southern areas. The population size of the first generation of adult L. striatellus emerged from late April to early May was similar or smaller compared with that of the second generation emerged in middle June in the middle parts of Korea. However, in the southern areas the population size of second generation was much greater than the first generation. The percentage of RBSDV viruliferous L. striatellus differed depending on the years, locations, and testing methods. The percentage of viruliferous vector was highest in southern plain areas and it tended to decrease with distance from the areas. The percentage of viruliferous vectors tested by enzyme-linked immunosorbent assay was higher than that tested by rice seedling test. The RBSDV infection rate of corn hybrids was highest at Daegu and ranged from 9 to 39% probably due to both a higher L. striatellus population and a higher percentage of viruliferous vectors. However, it was significantly lower in other areas and ranged from 0 to 13%.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.2
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• pp.129-133
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• 2007

To breed virus resistant rice variety, developing an efficient screening method is the most important. Two screening methods such as field screening and tray screening method have been used, but the efficiency of the field screening method is too low because of environment factors and the that of the tray screening method is good but screening capability is limited with only $200{\sim}300$ lines per year. To overcome those problems, mass screening method using screen house was developed. Barely as host plant of vector insect was grown in screen house in winter season. Then viruliferous insects are spread in the first spring of the initiation year and sustain them annually. Screening of virus resistance was tested two times in a year, the first screening was from April to June and the second from July to September. The virus infected rate of each susceptible varieties was increased to 92% for RSV and 100% for RDV from the second year. Also, this method can evaluate as many as $1,500{\sim}2,000$ pedigree lines in one time compared with the tray screening method. The result indicates that the mass screening method using screen house, which combines the advantages of the field and tray screening methods, is proven to be more efficient and reliable.

• Korean journal of applied entomology
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• v.16 no.2 s.31
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• pp.79-86
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• 1977

Four experiments were carried out under farmer's field conditions to determine economic threshold levels of major rice pests aad attempt a reduction in the number of insecticide applications. In the experiments were included check treatments, insecticide schedules representing the official recommendations to farmers, and several corrective treatments. A careful record was kept of insect pest densities and disease incidence. i) In the north at Suweon and Icheon where Chilo suppresalis. (Walk.), the striped rice borer, was active in the first generation, no significant yield differences were obtained between plots receiving several insecticide applications and those left totally unprotected. The mean yields were high (5.2-7.6t/ha). ii) First generation borer activity rising to $8.6\%$ injured tillers was below the economic threshold since no yield reduction was recorded in either japonica varieties or the high-yielding Tongil variety. iii) Evidence was obtained thst berer damage was made good by replacement of infested tillers (compensatory growth), C. suppressalis populations were always low in the second generation. iv) The experimental results obtained at Suweon and Icheon do not justify the present official recommendations of 6-7 pesticide applications. v) further south at Iri a substantial yield reduction occurred due to an early outbreak of stripe disease transmitted by Laodelphax striatellus (Fallen), the small brown planthopper; a mean of 1-2 individuals/hill was recorded immediately after transplanting. C. suppressalis probably contributed to this yield reduction. vi) Several applications against the vector failed to prevent the rapid spread of stripe to the susceptible variety in the Iri experiment: in surrounding fields the resistant Tonsil varivety was ralatively unaffected. vii) Pests of lesser importance were Nephotettix cinctieps (Uhler), Nilaparvata lugens (Stil), Sogatella furcifera (Horv..), and leaf miners.

• Korean journal of applied entomology
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• v.20 no.2 s.47
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• pp.117-121
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• 1981

The screening method of varietal resistance on the plant hoppers has generally been evaluated as a reaction of plant after infesting insects. However, feeding amount of insects to the varieties was investigated in this experiment. The new method using isotope $^{32}P$ for rice varietal resistance to plant hoppers was carried out through the following method. Insects tested were caged for a few hours on the plants which had absorbed $^{32}P$ solution in small vials for $24\~48\;hours$. After feeding, insects were killed in the refrigerator with formalin solution, and then were measured by the feeding amount as a count per minute (CPM) with the G.M. Counter. The results obtained were summarized as follows; 1. The apparatus of Type D(Fig. 2) was most effective and the safest among four others. 2. The optimum amount of $H_3PO_4$ solution was found to be $2\~3m1$. 3. Radioactivity of $0.7\mu\;Ci.\;^{32}P$ was sufficient to check varietal difference of feeding amount by the brown planthopper. 4. Radioisotope was found from the body of insects but not in the cuticular layer nymphs cast off.

• Research in Plant Disease
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• v.15 no.2
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• pp.63-67
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• 2009

Rice stripe virus (RSV) is one of Tenuivirus Group, which is carried by small brown planthopper. There is an outbreak of RSV in South Korea at 20Ot, and 2007. The infection caused by RSV had been investigated on weeds around the rice cultivated areas 13 region and 26 site including Jeonbuk Buan and Chungnam Seocheon. There have a doubt as to alternate host of RSV is total 15 Family and 50 Species including Gramineae 24 species of Duksaepul (Alopecurus aequalis), H. sativum var. vulgare etc.. There is identified the infected RSV in Festuca myuros, Alopecurus aequalis, Hordeum sativum var. vulgare, Trisetum bifidum, Echinochloa crus-galli var. crus-galli, Digitaria ciliaris among this species. Deulmuksae is the overwintering exotic weed which sprout in Autumn and wither in Spring and commonly growed as green manure crop or cover crop. In order to identify the infection rate furthermore, 111 samples which were collected at Buan Gyehwa-myeon region, and 50 samples from Seocheon Maseo-myeon in June, 2008, were ELISA tested. The results are 32 positives from Buan, 28.8% infection rate, 8 positives from Seocheon 16.0% infection rate. RSV infection of Deulmuksae is not reported currently, and follow report first describes the Deulmuksae as an alternate host of RSV.

• Korean journal of applied entomology
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• v.14 no.4 s.25
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• pp.193-198
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• 1975

This experiment was performed to clarify the concentration of rice stripe virus in the rice Plant leaves by serological test, and was attempted to inspect the virus carrier among small brown planthopper by antibody-sensitized hemagglutination test. The antiserum was prepared by injecting intervenously into the external marginal vein of the ear of a rabbit. The precipitin titer of it was 1 : 16. The rough virus fluid prepared from diseased leaves was centrifuged at 10.000 rpm, and then the supernatant solution was treated at $55^{\circ}C$ for 5 minutes and the solution clarified by removing the agglutinate was used as the antigen solution. Antibody-sensitized erythrocyte solution was prepared from sheep erythrocytes sensitized by rice stripe virus with tannic acid, and its agglutination titer was 1 : 512. The virus concentrations in flag leaves or first leaves just below them showing different symptoms was high with progressing the severity of symptoms. And the concentrations of the virus in leaves of varieties of the rice plant showing same degree symptom were lower in suscetible varieties, Sadominori, Palgoeng, Mangyong and Nihonbare, than in the resistant one, Tongil, but in Yooshin which was known as the resistant, lower rather than in Tongil. The reacton of antibody-sensitized hemagglutination test to inspect the virus carrier, was so highly sensitive that this reaction was recognized as a method which is able to Identify the carrier accurately in short time.

• Korean journal of applied entomology
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• v.36 no.4
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• pp.311-316
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• 1997

This study was conducted to evaluate the effect of temperatures on the egg and nymphal development andadult longevity of green mirid bug, Cvrtorhinus lividipennis Reuter. In addition, predation on eggs of brownplanthopper, Nilupurvurcz lugens ~t:l and small brown planthopper, L~orlelphux .striatellus Fallen by C.lividipennis were studied at different temperatures. Hatchability of C. lividipennis was about 96% at 23"C,88% at 26"C, 75% at 29$^{\circ}$C and 64% at 32$^{\circ}$C. Egg duration of C. lividipmnis was 1 1.0 days at 23"C, 10.0 at26"C, 6.7 days at 29$^{\circ}$C and 5.6 days at 32$^{\circ}$C. Nymphal duration of C. 1i1~idiperzni.ws as 13.7 days at 23"C,12.7 days at 26$^{\circ}$C. 10.2 days at 29$^{\circ}$C and 9.1 days at 32$^{\circ}$C regardless of food sources. Nymphaldevelopment was the shortest at 4th instar and the longest at 1st instar irrespective of temperatures and foodsources. Adult longevity of C. livirlipennis was was about 22.0 to 23.5 days at 23$^{\circ}$C. 19.0 to 20.0 days at26"C, 16.0 to 17.0 days at 2Y0C, and 1 1.0 to 12.0 days at 32$^{\circ}$C. There was no significant difference in adultlongevities on food sources. Number of eggs comsumed by adult C. lividipennis were about 56 to 61 and 56to 57,56 to 60 and 47 to 49,43 to 46 and 40 to 42, and 28 to 30 and 26 to 27 at 23'C. 20$^{\circ}$C. 29$^{\circ}$C and 32"C,respectively. Egg consumption by adult C. lividiprrznis was slightly higher at female and on N. lugens eggthan at male and on L. striatellus egg. Dail 2.0 to 3.0 eggs were consumed by adult C. lividipc,nni.s.ail 2.0 to 3.0 eggs were consumed by adult C. lividipc,nni.s.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.2
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• pp.81-86
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• 2013

'Mogwoo', a new high yield and whole crop silage rice (Oryza sativa L.) cultivar, was developed by the rice breeding team of the National Institute of Crop Science, RDA, Suwon, Korea, from 1999 to 2009, and was released in 2010. It was derived in 1999 from a cross between Dasanbyeo, having a high yield, and Suweon431/IR71190-45-2-1. A promising line, SR25848-C99-1-2-1, selected by the pedigree breeding method, was designated the name of 'Suweon 519' in 2007. This cultivar has about 155 days of growth period from seeding to heading, and is tolerance to lodging, with erect pubescent leaves as well as a long and thick culm. This cultivar has the same number of tillers per hill and higher spikelet numbers per panicle compared to Nokyang. 'Mogwoo' has longer leaves compared with other Tongil-type varieties. This new variety is resistant to grain shattering, leaf blast, bacterial leaf blight, and small brown planthopper. The biomass yield of 'Mogwoo' was 1,956 kg/10a in a regional test over three years. The result shows that 'Mogwoo' is adaptable to central and south-east plain areas of Korea.

• Korean journal of applied entomology
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• v.50 no.4
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• pp.343-352
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• 2011

The developmental period of Laodelphax striatellus Fallen, a vector of rice stripe virus (RSV), was investigated at ten constant temperatures from 12.5 to $35{\pm}1^{\circ}C$ at 30 to 40% RH, and a photoperiod of 14:10 (L:D) h. Eggs developed successfully at each temperature tested and their developmental time decreased as temperature increased. Egg development was fasted at $35^{\circ}C$(5.8 days), and slowest at $12.5^{\circ}C$ (44.5 days). Nymphs could not develop to the adult stage at 32.5 or $35^{\circ}C$. The mean total developmental time of nymphal stages at 12.5, 15, 17.5, 20, 22.5, 25, 27.5 and $30^{\circ}C$ were 132.7, 55.9, 37.7, 26.9, 20.2, 15.8, 14.9 and 17.4 days, respectively. One linear model and four nonlinear models (Briere 1, Lactin 2, Logan 6 and Poikilotherm rate) were used to determine the response of developmental rate to temperature. The lower threshold temperatures of egg and total nymphal stage of L. striatellus were $10.2^{\circ}C$ and $10.7^{\circ}C$, respectively. The thermal constants (degree-days) for eggs and nymphs were 122.0 and 238.1DD, respectively. Among the four nonlinear models, the Poikilotherm rate model had the best fit for all developmental stages ($r^2$=0.98~0.99). The distribution of completion of each development stage was well described by the two-parameter Weibull function ($r^2$=0.84~0.94). The emergence rate of L. striatellus adults using DYMEX$^{(R)}$ was predicted under the assumption that the physiological age of over-wintered nymphs was 0.2 and that the Poikilotherm rate model was applied to describe temperature-dependent development. The result presented higher predictability than other conditions.