• Korean journal of applied entomology
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• v.52 no.3
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• pp.243-248
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• 2013

This study was conducted to understand the settlement process of Ascotis selenaria larvae into citrus orchards with respect to oviposition site and analysis of the spatial distribution pattern of the larvae. A. selenaria eggs were not found on citrus trees in field and green house, but not on citrus trees in the field. A. selenaria larvae showed a significant clump distribution in the greenhouse. In the open citrus field, the index of dispersion was around 1.0 in most cases, with a weak clumping degree. However, the d-statistic was between -1.96 and 1.96, indicating a statistically significant random distribution. In addition, the Green's index (a clumping index) was very low in all cases, even though the clump distribution was accepted. for most samples, the probability distribution of larval frequency in the field satisfied the probability distribution functions of Poisson (random pattern) and the negative binomial (clump pattern) distribution. In addition, the temporal distribution of the larvae in the open field showed a pattern which was formed by colonizers from outside oviposition sites. Further, the difference in larval spatial distribution between field and greenhouse orchards was discussed.

• Journal of Forest and Environmental Science
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• v.11 no.1
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• pp.40-49
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• 1995

This study was carried out to investigated the developmental characteristics and spatial distribution of mango shield scale, Protopulvinaria mangiferae injuring to Elaeocarpus sylvestris(Lour.) This mango shield scale is parthenogentic. The oviparous female have three larval stages and adult. This species has two generation a year. The crawlers of the 1st generation emerged from late may to middle July, and those of the 2nd generation from early August to early October. Their emergence reached its peak in early part of the occurrence period. The crawlers disperse from 10 to 14 o'clock from ventral side of the adult and more than 90% had settled with in 8 hours on the leaves of E. sylvestris. The larvae and adults were distributed contagiously between trees. The adult densities were higher in the lower part of the crown than those in the middle or upper parts. But differents in densities were not significant among four directions. The distribution of the adult scales per leaf cluster showed an aggregation with a slightly colonized pattern.

• Korean journal of applied entomology
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• v.25 no.1 s.66
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• pp.17-20
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• 1986

Based on the data of rice injury caused by the first generation of striped rice borer(Chilo suppressalis (Walker)), which were collected in the three years from 1974 to 1976 in Sweon area, progress of the injury in relation to Degree Days was studied. Increase in the number of infested stems was strongly related to the dispersal features of larvae. The increase ceased at about 400 DD after modal emergence date when the larval distribution pattern became stable. The regression of the number of infested stems per infested hill on Degree Days was significant and the coefficients of determaination were 0.84 and 0.95 for 1974 and 1976, respectively. The regression coefficients in the two years were not statistically significant, suggesting a possibility for pre- diction of the mean number of infested stems per infested hill through a simple model.

• Korean journal of applied entomology
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• v.24 no.1 s.62
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• pp.1-6
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• 1985

The data on the striped rice, borer populations, collected in the four years from 1973 to 1976, was reanalyzed to study the characteristics in the aggregation pattern of the insect larvae in the paddy fields. The distribution pattern of the larvae was well fitted to the negative binomial model in both the first and the second generation. With reference to the Green's coefficient of dispersion estimated, the aggregation of the larvae was categorized into three phases: initial high aggregation, changing, and dispersed stable phase. Except the changing phase, each phase in each generation could be defined by a common k. The phase-change was initiated by the larval dispersal between hills of the rice plants: the larvae of the third stage and those of the fifth stage, for the first and second generation, respectively. The characteristics of the aggregation pattern were stable in the second generation. In the first genaration, the pattern was more or less variable, indicating that the life system of the insect in the first generation was more susceptible to the variations of the external physical factors than that in the second generation.

• Korean journal of applied entomology
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• v.42 no.4
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• pp.367-381
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• 2003

Dispersal polymorphism in insects Is a kind of adaptive strategy of the life history together with the diapause, consisting of the “long-winged or alate forms” of migratory phase and the “short-winged or apterous forms” of stationary phase. Dispersal polymorphism is a polymorphism related with the flight capability, and has three categories ; the wing polymorphisms, flight muscle polymorphisms, and flight behavior variations. Phase variation is another type of dispersal polymorphism varying in morphology, physiology and wing forms in response to the density of the population. The dispersal migration is a very adaptive trait that enables a species to keep pace with the changing mosaic of its habitat, but requires some costs. In general, wing reduction has a positive effect on the reproductive potential such as earlier reproduction and larger fecundity The dispersal polymorphism is a kind of optimization in the evolutionary strategies of the life history in insects; a trade-off between the advantages and disadvantages of migration. Wing polymorphism is a phenotypically plastic trait. Wing form changes with the environmental conditions even though the species is the same. Various environmental factors have an effect on the dispersal polymorphisms. Density dependent dispersal polymorphism plays an important role In population dynamics, but it is not a simple function of the density; the individuals of a population may be different in response to the density resulting different outcomes in the population biology, and the detailed information on the genotypic variation of the individuals in the population is the fundamental importance in the prediction of the population performances in a given environment. In conclusion, the studies on the dispersal polymorphisms are a complicated field in relation with both physiology and ecology, and studies on the ecological and quantitative genetics have indeed contributed to understanding of its important nature. But the final factors of evolution; the mechanisms of natural selections, might be revealed through the studies on the population biology.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.305-312
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• 2012

This study was conducted to elucidate the seasonal prevalence of adult mosquitoes and occurrence of anopheline larvae in Gimpo, Gyeonggi province, Republic of Korea. Sampling of adult mosquitoes was carried out 18 times from May to September in 2008, using light traps at six sites. A total of 48,919 individuals belonging to 16 species and 8 genera were collected. Aedes vexans nipponii (43%) was the most frequently collected, followed by Anopheles sinensis (34%) and Culex tritaeniorhynchus (14%). The seasonal prevalence of anopheline mosquitoes had a different occurrence compared to that of Cx. tritaeniorhynchus. Anopheline larvae were collected using a standard dipper (size = of 350 ml) at eight habitat types of 203 point locations. Anopheline larvae were confirmed from 138 points (63%). The average larval population per dipper was highest in the lotus plantation (6.9 individuals), followed by irrigation channel (4.5 ind.), dropwort field (3.4 ind.), fallow field (3.1 ind.), paddy field (1.8 ind.), swamp (1.4 ind.), and stream (0.2 ind.). There was no significant relationship observed between larval density and DO, pH, salinity, or distance from blood meal hosts (cowshed, pigsty, chicken-house). In the results of average nearest neighbor analysis (ANNA), the distribution of whole points for mosquito larval collection was clustered, and points with over 4.0 larvae per dipper were randomly distributed. Within the study area Haseong-myeon, those points where over 3.0 larvae were collected were of a dispersed distribution.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.87-94
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• 1985

The seasonal variations of the rate and intensity of metacercarial infection of C. sinensis in P. parva were observed. The fish were collected at Sun-Am River which located in Kim-Hae City, Kyong-Sang Nam Do (=Province), Korea, from March 1983, to February 1984 every month. A total of 788 fish was examined. The number of metacercariae in each fish was individually counted after the individual digestion by artificial gastric juice. The results were as follows: 1. During one year, 513 (65.1%) out of 788 fish were infected with metacercariae. In May, June, July and September, the infection rates ranged from 82.0% to 98.6% whereas the rates was relatively low in March, April, November and February ranging from 11.4% to 64.7%. 2. The intensity of infection was similar with those of infection rates. The mean intensity per infected fish was 103.0 and standard deviation was 118.9 throughout one year. The highest mean intensity was in June (294.8) and the lowest in November (11.1). 3. The observed frequency of fish with certain intensities of metacercariae were fitted to theoretical equations derived from negative binomial distribution in March, April, November and February (p>0.05). Meanwhile, the equation of lognormal distribution were fitted with the observed frequencies in May, June, July and September (p>0.05, p>O. 75). The variance/mean ratio varied by month. The value was the highest in July (814.3) and the lowest in November (158.8). Unlike our hypothesis, the metacercarial density of Clonorchis sinensis in its the most favorable fish host, Pseudorasbora parva showed considerable seasonal variations in the hyperendemic area. The possible factors were discussed.

• Korean journal of applied entomology
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• v.60 no.2
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• pp.221-228
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• 2021

The fall armyworm (FAW), Spodoptera frugiperda (Smith), is a notorious invasive migratory pest native to the tropics that has recently invaded South Korea with subsequent damage to cornfields. This study was conducted to evaluate the damage patterns on corn plants caused by the migratory and subsequent generations of FAW. The early migrant generation-related infestation rates reached an average of 13.2%, ranging from a minimum of 4.3% ('Allog-i') to a maximum of 33.0% ('Chodang'), depending on the corn cultivar. The proportion of FAW larvae-infested corn plants, in which the FAW survived until the pupal stage was 19.3%. The subsequent FAW generation caused considerable damage to the ears, resulting in 60% of ears with damaged kernels. This damage was markedly different from the nearly negligible damage caused by the migratory generation. The FAW larval dispersion was the most dynamic during the second instar stage and occurred along the same cornrow in line. In addition, we discuss the development of corn pant damage patterns caused by FAW. In summary, the results of the present study would provide useful basic information for the damage analysis of this pest for future studies.

• Journal of Apiculture
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• v.32 no.3
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• pp.163-170
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• 2017

Small hive beetle (SHB, Aethina tumida Murray (Coleoptera: Nitidulidae) is a honeybee pest infesting combs and stores inside the hive. Contamination of the SHB on Apis mellifera colonies were firstly noticed on September 23, 2016, in Miryang City, Gyeongnam Province in Korea. After that, on October 5, 2016, we investigated the spatial distribution of SHB inside the hive and outside soil within the apiary. Total of 169 beehives were observed. We found all stages of SHB inside or outside of hives. 61% of hives infested with the adult SHB still had live honeybees whereas hives containing larval SHB did not have bees, implying colony destruction In hives with live bees, infestation density was higher as bee population became higher. Coefficient of dispersions (CD) showed significant clumped distribution of infestation among hives. CDs were much higher inside hive than outside soil. Our results indicates SHB could result in honeybee colony collapse it not managed properly. Also even during October, there are new infestation into honeybee colonies and every stage of SHB could still be able to develop. Further detailed analysis of this insect' adaptation in Koran environment could help guide the management strategies of the invaded new pest of honeybee.

• Journal of Sericultural and Entomological Science
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• v.30 no.1
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• pp.8-19
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• 1988

The objective of the present study was to investigate the behavioral responses of sillkworm (Bombyx mori) larvae to: the dominant effect of walking distace: and the relationships between walking distance and the various economic characters on yellow sheets. The means of walking distances of progeny from F2 and F1 F1 and F2 generations, which was a hybrid between the long and the short walking distances, were shorter than those of parents. This may indicate that the genes for the short walking distances were partially dominant over those for the longwalking. Estimated broad sense heritability of larval walking distance was different for each larval instar, which fell into the range of 52∼84%. Genetic correlation was apparent between walking distances of all larval stages and some economic characters. The number of cocoons per liter and the period from incubation to emergence have shown the positive genetic correlation with walking distances. The cocoon yield, the sing cocoon weight, and the cocoon shell weight have shown to be in the negative correlation with walking distances. No correlation was observed between walking distances of the mature larvae and any economic characters. The analysis by the path coefficient showed negative direct effect of walking distances on the cocoon yield, and positive indirect effect on the single cocoon weight and the cocoon shell weight.