• Korean journal of applied entomology
• /
• v.43 no.3 s.136
• /
• pp.249-255
• /
• 2004

This study was conducted to determine Seasonal Occurrence, soybean damage and control efficacy of bean bug, Riptortus clavatus Thunberg at soybean field in Honam province. Occurrence of R. clavatus varied at seeding times with annual difference. The peak occurrence of R. clavatus was appeared at late of August for late May seeding and middle of September for middle June seeding. There was difference in the peak occurrence of R. clavatus due to different growing stages affected by different weather conditions though soybean was seeded at same time. If the rate of soybean seed damage area by R. clavatus sucking increases, the germinating rate was greatly decreased. If the rate of soybean seed damage area is above 50 percent, in particular, the germinating rate was very low with 2 percent. Control efficacy against R. clavatus was the highest with $91\%$ at 3 times treatment of insecticide at $R_4$ (full pod stage) + $R_5$ (Beginning seed stage) +$R_6$ (full seed stage) of soybean growing stages in field.

• Journal of Korea Water Resources Association
• /
• v.35 no.1
• /
• pp.109-124
• /
• 2002

This study is an effort to develop a stochastic model of precipitation series that preserves the pattern of occurrence of precipitation events throughout the year as well as several characteristics of the duration, amount, and intensity of precipitation events. In this study an event cluster model is used to describe the occurrence of precipitation events. A logarithmic negative mixture distribution is used to describe event duration and separation. The number of events within each cluster is also described by the Poisson cluster process. The duration of each event within a cluster and the separation of events within a single cluster are described by a logarithmic negative mixture distribution. The stochastic model for hourly precipitation occurrence process is fitted to historical precipitation data by estimating the model parameters. To allow for seasonal variations in the precipitation process, the model parameters are estimated separately for each month. an analysis of thirty-four years of historical and simulated hourly precipitation data for Seoul indicates that the stochastic model preserves many features of historical precipitation. The seasonal variations in number of precipitation events in each month for the historical and simulated data are also approximately identical. The marginal distributions for event characteristics for the historical and simulated data were similar. The conditional distributions for event characteristics for the historical and simulated data showed in general good agreement with each other.

• Ocean and Polar Research
• /
• v.32 no.3
• /
• pp.187-201
• /
• 2010

The purpose of this study was to investigate the temporal and spatial variability of taxonomic groups and major species of the mesozooplankton community in Lake Shihwa, Korea. Monthly collections were carried out at five stations in Lake Shihwa for a period of one year. The mesozooplankton community showed distinct seasonal variability with water temperature and salinity. Major mesozooplankton species in each seasonal community were derived from non-metric MDS and SIMPER as follows: winter community (Acartia hongi and Eurytemora pacifica), spring community (Acartia hudsonica and Polychaeta larvae), summer community (Acartia sinjiensis, Pavocalanus crassirostris, Evadne tergestina and Cirripedia nauplii) and fall community (Paracalanus indicus and Podon leuckarti). The succession of the seasonal species, A. hudsonica and A. sinjiensis, was the most remarkable event during the seasonal changes of the mesozooplankton community. The species response curve of these species fitted with the logistic regression in relation to water temperature and salinity. The curve also correctly represented the characteristics of the occurrence of A. hudsonica and A. sinjiensis in Lake Shihwa.

• Korean journal of applied entomology
• /
• v.45 no.1 s.142
• /
• pp.9-13
• /
• 2006

Seasonal occurrence of thrips and its damage on fruits were studied at in open field red pepper in Jeonbuk Province. The kind of thrips were Franklinella occidentalis and F. intonsa. The ratio of F. occidentalis was about 30% in periods of survey. Density of thrips increased in late May and showed peak occurrence in early to middle July. The peak occurrence of thrips was appeared at 4 pentad June, 2 pentad July, 3 pentad August, and 4 pentad September. The part of fruit damaged by thrips became discolored and roughed. When turned red, the colors of damaged parts changed from dark brown to yellowish brown. As a result, damage fruits by thrips decreased marketability. The percent of damaged fruits was highest in Imsil at 20.8% in early August. Density of thrips on flowers was highest in middle July.

• 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 Pharmacognosy
• /
• v.22 no.2
• /
• pp.85-90
• /
• 1991

The seasonal variation of two flavonol glycosides, icariin and epimedoside A, in the aerial parts and underground parts of Epimedium koreanum from June through September was investigated. The icariin concentration was decreased with time in both parts. Epimedoside A concentration was fluctuated, being highest in June and lowest in July in the underground parts. In the aerial parts, however, it was almost same in concentration. Determinations were made of the occurrence of two new flavonol glycosides, 2‘-O-rbamnosyl ikarisoside A and 2’-O-rhamnosyl icarisid II in the aerial parts and their changes in concentration were similar to those in the underground parts, being highest in July in both parts.

• Ocean and Polar Research
• /
• v.36 no.4
• /
• pp.437-445
• /
• 2014

A time-series sediment trap was operated at a water depth of 4950 m from July 2003 to May 2004 at KOMO station ($10^{\circ}30^{\prime}N$, $131^{\circ}20^{\prime}W$) in the northeastern equatorial Pacific, with the aim of understanding the temporal variation of planktonic foraminifera assemblages in response to the seasonal shift of Inter-Tropical Convergence Zone (ITCZ). A total of 22130 planktonic foraminifera specimens belonging to 30 species and 11 genera were identified, which shows a distinct seasonal variation with high values (125~288 specimens $m^{-2}day^{-1}$) in the winter to spring (December-May) and low values (16~23 specimens $m^{-2}day^{-1}$) in the fall (September-November). In addition, seasonal ecological differences of foraminifera assemblages are distinctly recognizable: omnivorous foraminifera occurred predominantly during the summer season, whereas herbivorous ones were dominant during the winter season. Such seasonal variations correspond to the seasonal shift of the ITCZ. Enhanced occurrence of herbivorous species during the winter-spring season seems a result of surface water mixing generated by the southward shift of the ITCZ. The increase in omnivorous species during the summer season may be due to the northward movement of the ITCZ caused by weakened wind speed, resulting in the intensification of water column stratification and nutrient-poor environment. A significant reduction of planktonic foraminifera specimens during the fall is attributed to heavy precipitation and reduction in light intensity.

• Proceedings of the Korean Society of Applied Entomolohy Conference
• /
• 2004.05a
• /
• pp.96-96
• /
• 2004

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2006.04a
• /
• pp.226-227
• /
• 2006

• Korean journal of applied entomology
• /
• v.46 no.1 s.145
• /
• pp.27-35
• /
• 2007

Seasonal occurrences of tobacco cutworm, Spodoptera litura and beet armyworm, Spodoptera exigua were observed using sex pheromone traps at different locations and climatic regions in Yeongnam district. In Gyeongnam province, S. litura male adults kept occur from mid or late March to mid or late November Whereas in Gyeongbuk province, S. litura occurred from mid or late April to early or mid November with exception at Uljin where it was late May to late October. According to the climatic regions, the peak occurrence of S. litura was middle September at the southern coast region, late August at the inland and the basin region, middle August at the inland mountainous region, and early September at the eastern middle coast region. The occurrence rate of S. litura was the highest at Jinju with 20.0% and the lowest at Changyeong with 8.6% in Cyeongnam province, while it was the highest at Sungju with 3.3% and the lowest at Uljin with 0.8% in Gyeongbuk province. In accordance with the climatic regions, the occurrence rate of S. litura was the highest at the inland region with 43.7%, and followed by the southern coast region (36.3%), the basin region (8.4%) and the inland mountainous region (7.0%), and was the lowest at the eastern middle coast legion with 4.6%. On the other hand, S. exigua occurred from early March to middle November with the exception of the eastern middle coast region including Pohang, Yeongdeog and U]ien in Cyeongbuk province where it occurred from mfd April to middle November. The peak occurrence of s. exigua was early August at the inland region, the basin region and the inland mountainous region, and was late of August at the southern coast region and the eastern middle coast region. The occurrence of S. exigua was the highest at Changyeong with 1.6% and the lowest at Busan with 0.4% in Gyeongnam province, while it was the highest at Sungju with 37.2% and the lowest at Uljin with 2.7% in Gyeongbuk province. The climatic regional occurrence rate of S. exigua was the highest at the basin region with 54.3%, and followed by the inland mountainous region (29.9%), the eastern middle coast region (9.3%) and the inland (3.9%), and was the lowest at the southern coast region with 2.6%. As a whole, S. litura occurred more in Gyeongnam province than Cyeongbuk province, while S. exigua occurred more in Gyeongbuk province than Gyeongnam province. According to the regions grouped by climatic differences, the occurrence of S. litura and S. exigua was the highest at the inland region in Gyeongnam province and at the basin region in Gyeongbuk province. The total number of S. litura captured by sex pheromone trap was 2.4 times higher than that of S. exigua. However, the first occurring time and the peak occurrence of S. exigua were slightly earlier than those of S. litura.