• Korean journal of applied entomology
• /
• v.34 no.2
• /
• pp.147-153
• /
• 1995

The occurrence of Oriental Tobacco Budworm (OTB), Helicoverpa assulta (Guenee), larvae in early and late planted tobacco fields showed tow or three distinct peaks. The parasitoid, Campoletis chlorideae Uchida, occurred for a short period with one peak following th second peak of OTB in early planted fields. However, in late planted fields, the parasitoid occurred as long as the OTB larvae were abundant. The OTB larval density was higher in late planted fields than in early planted fields. Among four varieties of tobacco, the OBT larval occurrence was relatively high on NC-744 throughout the season. However, more parasitoid cocoons were found in Burleyf-21 and NC-82. The seasonal occurrence of the larval parasitoid, C. chlorideae, assessed by an OTB larval release and recovery method, continued from late June to early September and relatively higher abundance was noticed from early July to late August. In a field cage evaluation of C. chlorideae as a biological control agent of OTB larvae, higher rate of C. chlorideae release (4 females/2$\m^2$) resulted in higher larval parasitism (86.1%) and less leaf damage (8.7%) in tobacco. The leaf damage by OTB larvae was significantly high in the untreatment plot (23.2%) and the lowest damage (1.6%) was recorded in the chemical treatment plot.

• Korean journal of applied entomology
• /
• v.14 no.2 s.23
• /
• pp.53-58
• /
• 1975

The local variabilities of resistance to Malathion and NAC (Sevin) were studied during 1973 with the strains of small brown planthopper (Laodelphax striatellus Fallen) collected from Jinjoo, Sunsan, Milyang, Kwangjoo and Iri districts of southern part of Korea. The susceptible lab strain used for this study has been reared successively in the laboratory without exposure to any insecticide since 1970. The insecticides were applied topically in acetone to the thoracic sternum of the adult insects. $LD_{50}$ values of Malathion to the insect were varied with the locality of the planthoppers. Relatively high levels of resistance to Malathion were observed in the strains of Jinjoo and Suntan; showing 27.7 times in female and 24.9 times in male for Jinjoo stram and 18.4 times in female and 13.8 times in male for Sunsan strain as compared with the susceptible lab strain, and in other strains of Milyang, Kwangjoo and Iri the levels of resistance to Malathion were still less than 5 times. However, there was no any specific difference among the strains in susceptibility to NAC. The malathion-resistant strain of the small brown planthopper seemed to be still localized in some regions of· Korea. The susceptibility of the planthoppers to Malathion was varied with the sex; $LD_{50}$ values based on the individual (ug/insect) were higher in female than in male, while the values based on the body weight (ug/g) conversely higher in male than in female.

• Korean journal of applied entomology
• /
• v.14 no.2 s.23
• /
• pp.65-70
• /
• 1975

The study was planned to detect resistance levels of striped rice borers (Chilo suppressalis Walker) and green rice leafhoppers(Nephotettix cincticeps Uhler) from different localities to organophosphate and carbamate insecticides using topical application. Strains of overwintering striped rice borers were collected from 7 different areas in Gyeonggi Province and they were kept under conditions of about $25^{\circ}C$ for 10 days. Overwintered and reared larvae of striped rice borers were compared for response to insecticides. The strains of green rice leafhopper were collected from Iri, Milyang, Pyongtaek, Echeon and Suweon. Insects were multiplied in the lab. All insecticides tested were organphosphates(MPP, MEP and Diazinon) and carbamate (NAC), which have been used in control of rice insect pests for over past 10 years. The results obtained were as follows; a. With MPP compound, resistant levels of the Joam, Suweon, and Echeon strains of C. suppressalis were from 2 to 4 times as compared with the Yangpyong strain. b. With MEP insecticide, resistant levels of the Kimpo, Pyongtaek, Yongin, Echeon, Suweon, and Joam strains of C. suppressalis were from 2 to 6 times as compared with the Yangpyong strain. c. With Diazinon, resistant levels of the Suweon strain of C. suppressalis were 3 times greater than the Yangpyong strain; but the resistant levels of Kimpo, Pyongtaek, Yongin, and Echeon strains approximated the later. 4. The overwintered larvae of C. suppressalis were more tolerant to the insecticides than the larvae reared in the lab. e. With MEP, resistant levels of the Iri, Milyang, and Pyongtaek strains of N. cincticeps to the Suweon strain showed 13, 8, 7 and4 times, respectively. f. With MPP, resistant levels of the Iri and Pyongtaek strains of N. cincticeps were 7 and 4 times as compared with the Suweon strain, respectively. g. With NAC, resistant levels of the several strains of if. cincticeps showed no difference, and seemed not to have developed resistance yet.

• Korean journal of applied entomology
• /
• v.53 no.4
• /
• pp.415-425
• /
• 2014

This study investigated population fluctuations in two mite species in apple orchards over 20-year period. The occurrence of two major mite pests infesting apple trees, two-spotted spider mite Tetranychus urticae and European red mite Panonychus ulmi (Acari: Tetranychidae), was investigated from 1992 to 2011 in major apple-producing districts, including four to eight cities, in the southern part of the Republic of Korea. The 20-year trend revealed that more orchards were infested by T. urticae from 1992 to 1999, but thereafter P. ulmi became dominant. The observed mean density of P. ulmi was consistent, whereas that of T. urticae fluctuated during this period. The analysis of occurrence in four time periods reveals that the density of T. urticae decreased after 2002. The monthly sampling, revealed that the density of P. ulmi was higher in April, whereas the density of T. urticae was higher from May to August. This change may be due to a change in the frequency of pesticide spraying, ground vegetation management, a decrease in nitrogen fertilization, and the overall orchard management practices. However, this projection should be examined in more detail. On the basis of the findings of this study, it can be concluded that cultural practices, including fertilization, and environmental changes, such as pesticide spray frequency and integrated pest management practices, affect species dominance and population densities of the two mite species in apple orchards.

• Korean journal of applied entomology
• /
• v.53 no.4
• /
• pp.367-373
• /
• 2014

In order to investigate the impact of recycling agricultural wastes as feed for mealworm (Tenebrio molitor), we evaluated the replacing effect by the different level of tangerine shell, Chinese cabbage, king oyster mushroom (Pleurotus eryngii) and Enoki mushroom (Flammulina velutipes) substrates on wheat bran feed. Larval survival rate, larval weight, developmental period of larva, pupation rate and pupal weight were evaluated. In tangerine shell and Chinese cabbage replacement group, no replacing effects found. In all groups replacing by spent King oyster mushroom (Pleurotus eryngii) substrate, survival rate of larva was similar to that of control group but larvae weighed less than control group significantly. Developmental period of larva increases in the group of King oyster mushroom substrate replacement. Larval and pupal weight in Enoki mushroom (Flammulina velutipes) substrate by the level of 40 and 50%, replacement effect showed best results in successive breeding considering pupation rate. It is concluded that replacing 40 and 50% of Enoki mushroom (Flammulina velutipes) substrate is appropriate to substituted diet of Tenebrio molitor larvae.

• Korean journal of applied entomology
• /
• v.22 no.1 s.54
• /
• pp.1-6
• /
• 1983

The survey on the occurrence and distribution of barley stripe disease was conducted in the farmer's field of 19 gun (county) throughout Yeongmm area in May of 1982, in order to obtain a basic information on the breeding of resistant varieties, and for control of the disease. The percent of infected culms of barley stripe disease in Gyeongnam province (Southern Yeongnam) was higher $(13.7\%)$ them in Gyeong-bug $(6.9\%)$, northern Yeongnam, and especially, Ham-an, Milyang, Eui-chang and Weol-seong were severly occurred. The cultivar of Millyang 6 was slightly infected while the cultivars Olbori and Oweolbori were severely infected by the disease. Among soil conditions, the barley plant grown in the loam, clay and clay loam texture which have more availble moisture, and that of the plant cultivated in the poorly drained soils were shown to have severe infection. The barley plant grown in the soils in local valley $(18.8\%)$ where is frequently over saturated with water showed the more infection the barley plant grown in plains $(9.5\%)$. Generally, the poorer the soil drainage the more severeinfection occurred. Among cultivation conditions, the earlier the sowing dates of the barley, the less the percent of infected culms was observed. The heavier or lighter application of N fertilizer than the optimum to barley plant seemed to cause more infection.

• Korean journal of applied entomology
• /
• v.9 no.1
• /
• pp.7-13
• /
• 1970

1. Kum Nam Poong which is highly susceptible to bacterial leaf blight was used as the host plant throughout this experiment. Xanthomonas oryzae 6526 was inoculated on the top of upper leaves by single needle inoculation method. After 14 days, the enlarged spots were examined in the experimental pots. Each of 3 levels of nitrogen, phosphate and potassium pots were arranged at random with three replications. 2. The amounts of nitrogen fertilizer applied and the lesion development of bacterial leaf blight were positively correlated regardless of application of phosphate and potassium fertilizers. 3. The effect of phosphate fertilizer on the lesion development was not significantly different from standard level. The lesion development was stimulated when the amount of phosphate fertilizer was increased as twice as standard level. 4. The inhibitory effect of potassium fertilizer on leaf blight was maximum by applying standard level. The stimulative effect of potassium fertilizer on the lesion development, however, was noticed. when potassium fertilizer applied was increased as twice as the standard level. 5. The heading date and spike number of rice plant were significantly correlated with the lesion development, and such phenomena were depended on the amount of nitrogen fertilizer applied regardless of the other fertilizers applied in this experiment.

• Korean journal of applied entomology
• /
• v.41 no.4
• /
• pp.293-298
• /
• 2002

Cadusafos and fosthiazate were applied at the rate of 1.8 g a.i./6$\m^2$ as pre-plant or pre-plant＋post-plant treatments on winter-grown oriental melon in a greenhouse soil infested with Meloidogyne arenaria. Nematicides reduced root-knot nematode population from 35 to 90% compared with control； fosthiazate was better than cadusafos (P ＝ 0.003) and fosthiazate pre-plant＋post-plant application reduced nematode population densities as much as 90%. Nematicides increased yield in an average of 23% (11-38%) in May, 39% (2-65%) in June, and 31% (12-46%) for the total (P ＝ 0.085). The residue in the fruit of oriental melon by post-plant treatment of fosthiazate exceeded maximum residue limit of 0.2ppm, while the Cadusafos residue was below the limit. It is concluded that fosthiazate cannot be used as a post-plant treatment in winer-grown oriental melon with overall consideration, i. e., danger of residue, value of melon, costs of nematicide, consumer demand on safer agricultural products, and effects of fallow.

• Korean journal of applied entomology
• /
• v.13 no.1 s.18
• /
• pp.41-45
• /
• 1974

A total of 230 apparently healthy looking potato stocks and 80 potato stocks with symptoms of virus infection were collected from various seed potato farms in Korea and the incidence of potato virus X (PVX), potato virus S (PVS), potato virus M (PVM) and potato virus Y (PVY) was determined by serological microprecipitin tests. Results obtained are as follows. 1. Serological microprecipitin test retreated the presence of PVX, PVS, PVM and PVY in a number of potato stocks grown for the production of seed potatoes in Korea. 2. The occurrence of potato virus M is reported here for the first time in Korea with experimental evidence. 3. Practically $100\%$ (290 stocks, of the apparently healthy looking potato stocks were demonstrated to be infected with both PVX and PVS. The infection percentages of potato stocks with combination of PVX, PVS, PVM and PVY were as follows. PVX+PVS+PVM:$10.3\%$, PVX+PVS+PVY:$4.5\%$, PVX+PVS+PVM+PVY:$1.03\%$ 4. Irish Cobbler and Shimabara, which are the two major potato varieties in Korea, appear to be symptomless carriers of PVX and PVS. However, when these varieties were infected additionally with PVY, usually severe symptoms resulted. 5. Serological microprecipitin technique appears to be highly suitable for early, quick and reliable diagnosis of PVX, PVS PVM and PVY. It is particularly suited for large scale testing of seed potato stocks for the presence of viruses mentioned above.

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