• The Korean Journal of Malacology
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• v.21 no.1
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• pp.25-31
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• 2005

The embryos of marine bivalves have been commonly used in bioassays for the quality assessment of marine environments. Although several standard protocols for developmental bioassay with bivalves have been already proposed, there have been few trials for applying these protocols in environmental assessment, or for developing new protocol with Korean species. So, there is a strong need to establish the standard bioassay protocols using bivalves commonly found in Korean waters. Prior to developing a new protocol, it is essential to know the optimum conditions for the reliable bioassay procedures. Here, we established the purpose of this study to determine the optimum bioassay conditions for successful development of a common mussel, Mytilus galloprovincialis. The conditions considered as critical for developmental bioassay, and determined in this study were; (1) temperature, (2) salinity, and (3) initial density of embryo. The optimal temperature for developmental bioassay of M. galloprovincialis was determined as $15^{\circ}C$. At this temperature, the required time for the embryo to become veliger larva was 48 hr. The acceptable range of salinity for the embryotoxicity test using M. galloprivincialis was from 30 to 35 psu, which was narrower than that of the natural habitat of adult populations. The optimum density of embryo at the beginning of bioassay was 100 embryos/ml. Over this density, the proportion of normally developed larvae decreased significantly. The results obtained in this study will serve as a basis for preparation of the standard bioassay protocol using embryo of M. galloprovincialis.

• Korean journal of applied entomology
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• v.20 no.4 s.49
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• pp.217-222
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• 1981

As a primary study on the economic injury level of A. tokionis larval populations in tobacco fields, we carried out some experiments for the evaluation of sampling efficiency of 3 sampling methods (pit-fall traps of apple pomace and rice bran, and clover patches) for the larval population and the regressions between loss and infested larval density The $10\times10cm$ clover patch showed a better sampling efficiency $11.8\;to\;18.0\%$ than the others. The sampling efficiency of clover patch becomes higher when the plots did not have any green plants. The linear regression equation (Y=4.2+1.383x) between loss (Y:kg/10a) and infested larval density (X: no. of larvae/plot) which was obtained by substitution of damage ratio and corrected damage ratio fitted the observed data better than the one (Y=2.68X) obtained without substitioning.

• Korean journal of applied entomology
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• v.45 no.3 s.144
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• pp.375-380
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• 2006

A solitary endoparasitoid, Cotesia plutellae, parasitizes diamondback moth, Plutellae xylostella. It has been suggested that its antennae are a major sensory organ to search host and recognize host developmental and other physiological condition during parasitization. This research was performed to understand the parasitic behavior of C. plutellae by analyzing sensory types and their numbers on the antennae using scanning electron microscope. There was no significant difference in antennal length in both male and female C. plutellae, in which both sexes had 16 flagellomeres. Three different types of sensilla (trichoid, seta, and placodea sensilla) were located mostly on flagella and analyzed in their density on the different antennomeres. Trichoid sensillum was the major sensory type and showed about 87% density among all sensilla. Both trichoid and placodea types of sensilla exhibited even numbers on all flagellomeres with some decrease at terminal segments. In contrast, seta form of sensilla showed drastic increase in its density at distal part after 9th flagellomere. When distal half of flagellomeres were cut off, the C. plutellae could not parasitize host larvae. Even when only four distal flagellomeres were removed, the parasitism showed only 30%. These results indicate that C. plutellae antennae are required for parasitism and suggest that seta form of sensilla may play significant roles in recognizing host for parasitization.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.4
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• pp.217-227
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• 2007

The western cherry fruit fly, Rhagoletis indifferens Curran (Diptera:Tephritidae), is the most important pest of cultivated cherries in the Pacific Northwest area of the United States, being widely distributed throughout Oregon, Washington, Montana, Utah, Idaho, Colorado and parts of Nevada. The control of R. indifferens has been based on calendar sprays after its first emergence because of their zero tolerance for quarantine. Therefore, a good prediction model is needed for the spray timing. This study was conducted to obtain the empirical population dynamic information of R. indifferens after overwintering in the major cherry growing area of the Pacific Northwest of the United States, where the information is critically needed to develop and validate the prediction model of the fruit fly. Adult fly populations were monitored by using yellow sticky and emergence traps. Larvae growth and density in fruits were observed by fruit sampling and the pupal growth and density were monitored by pupal collection traps. The first adult was emerged around mid May and a large number of adults were caught in early June. A fruit had more than one larva from mid June to early July. A large number of pupae were caught in early July. The pupae were collected in various period of time to determine the effect of pupation timing and the soil moisture content during the winter. A series of population density data collected in each of the developmental stage were analyzed and organized to provide more reliable validation information for the population dynamic models.

• Korean journal of applied entomology
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• v.28 no.3
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• pp.167-174
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• 1989

A confined field assessment on the integrated control of vector mosquitoes (Anopheles sinen- sis and Culex tritaent'orhynchus) was conducted by timely treatment of Bacillus thuringiensis(H-14) formulation in the presence of larvivorous fish (Aplocheilus lalipes) in natural rice fields of $30,000M^2$ at Yongam, South Korea Cholla Province from July through October in 1988. In presence of larvivorous fish (Aplocheilus) at lower density of 0.6 fish per $M^2$ water surface, mosquito vector control rates ranged 55. 0~57. 6% from July through August, and when the mosquio density started to increase with over 10 larvae on the average per sample, B.t.(H-14) formulation treatment at the rate of 1. 0 Kg/ha made 100% vectors reduc¬tion in 24 hours, the control sustained above 98% until the test was terminated on October 11th. In the fish introduced rice paddies with Aphyocypris chinensis at the density of above 1. 5 fish per $M^2$, a satisfactory degree of vector control was obtained by 88. 2~96. 7% in 2 week period until September 21st. In the absence of larvivorous fishes, B.t. (H-14) treatment made 100% control in 24 hours, however, vector population rebound appeared in day 7, required to make additional treatment to suppress population down.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.322-328
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• 2016

This study investigated the effects of temperature, salinity, and algal diet to find the optimal conditions for 5 days for the mass culture of the tropical tintinnid, Metacylis tropica. This tintinnid had a small, hyaline, and ovoid lorica. The oral diameter, length, and maximum width of the lorica were $36.7{\mu}m$, $49.5{\mu}m$, and $44.5{\mu}m$, respectively. In the temperature experiments, the highest maximum density and population growth rate were observed at $30^{\circ}C$ with 340.7 cells/mL and 1.1/day, respectively. Lower salinities adversely affected the population growth of M. tropica. The maximum density was observed at 33 ppt (840 cells/mL). In the diet experiments, M. tropica fed Isochrysis galbana showed the highest density (413 cells/mL) and population growth rate (1.2/day). As a result, M. tropica is appropriate as a potential prey organism for early fish larvae with smaller mouths because the tintinnid has a relatively small size compared to the rotifer. In addition, the conditions of $30^{\circ}C$, 33 ppt and supplying I. galbana would be effective in the cultivation of M. tropica.

• Journal of Aquaculture
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• v.6 no.3
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• pp.133-146
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• 1993

Monthly variation of fatness index of the shortnecked clam was investigated at Moonhangri in Namhaedo of the southern coast of Korea from April 1991 to March 1992. The standing crops of umbo stage larvae and spats of this bivalve were also investigated. The results are as follows: The ranges of a monthly average water temperature and salinity were $6.9\~23.5^{\circ}C$ and $29.6\~33.1%o$ during the investigation period. Fatness index of the shortnecked clam decreased suddenly from June to September, which seemed to be spawning season. The umbo stage larvae of the clam were observed from May to November. The standing crops of the larvae were $883\;inds./m^3$ in August and$68\;inds./m^3$ in November. The observed number per ~ of the spats varied with the month and the different exposure time zones. The highest density $(1,508\;inds./m^3)$ was observed 1 hour exposure zone in August, and the lowest one $(28 inds./m^3)$ at 1 hour exposure station in April. Even the observed number of the spats below 4 mm in shell length were high in 1 and 3 hour exposure zones, the spats above 4 mm in shell length were observed mainly at 3 hour exposure zone.

• Journal of Aquaculture
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• v.11 no.4
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• pp.449-455
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• 1998

The small size food organism(under the size 150${\mu}m$) is needed as food for early stage of marine fish larvae of small mouse (e.g the group of grouper). This study was investigated to develop a method for copepod Apocyclops sp. culture in combination with the rotifer B. rachionus for stable culture of copepod species and harvest of various size food organisms. The culture conditions as temperature, salinity, culture volume, photo period, culture preiod and observation interval were 25${\circ}C$, 22ppt, 40ml, all dark except to observation time, 16 days and every two day during the experimental period, respectively. The Tetraselmis suecica was used as the food for the two testing orgtanisms. After every two day counting, theses two organisms were transferred to fresh culture tanks with Tetraselmis suecica of $7{\times}10^5$cells/ml. In the mixed culture of B. rotundiformis and A. sp., growth of rotifer was suppressed by mixed culture with A. sp. whereas the growth of copepod Apocyclops was promoted in the mixed culture with rotifer B. rotundiformis (the maximum density was 22 individuals/ml through the 16 culture days). Moreover, the number of copepod nauplius were promoted about 2 times in the mixed culture compared to the numbers in single species culture. With this combination culture, the havested two food organisms of variable sizes. This size variation of food organisms was useful tools for larval rearing of small mouse marine fish larvae and next step food organism size of post hatched larvae.

• Korean journal of applied entomology
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• v.50 no.3
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• pp.235-245
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• 2011

Temperature-related parameters of Panonychus citri (McGregor) (Acarina: Tetranychidae) development were estimated and a stage-structured matrix model was developed. The lower threshold temperatures were estimated as $8.4^{\circ}C$ for eggs, $9.9^{\circ}C$ for larvae, $9.2^{\circ}C$ for protonymphs, and $10.9^{\circ}C$ for deutonymphs. Thermal constants were 113.6, 29.1, 29.8, and 33.4 degree days for eggs, larvae, protonymphs, and deutonymphs, respectively. Non-linear development models were established for each stage of P. citri. In addition, temperature-dependent total fecundity, age-specific oviposition rate, and age-specific survival rate models were developed for the construction of an oviposition model. P. citri age was categorized into five stages to construct a matrix model: eggs, larvae, protonymphs, deutonymphs and adults. For the elements in the projection matrix, transition probabilities from an age class to the next age class or the probabilities of remaining in an age class were obtained from development rate function of each stage (age classes). Also, the fecundity coefficients of adult population were expressed as the products of adult longevity completion rate (1/longevity) by temperature-dependent total fecundity. To evaluate the predictability of the matrix model, model outputs were compared with actual field data in a cool early season and hot mid to late season in 2004. The model outputs closely matched the actual field patterns within 30 d after the model was run in both the early and mid to late seasons. Therefore, the developed matrix model can be used to estimate the population density of P. citri for a period of 30 d in citrus orchards.

• Korean journal of applied entomology
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• v.52 no.2
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• pp.71-74
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• 2013

The moving period and overwinteing site of Scrobipalpa salinella (Zeller) were investigated in Gimje, Jeonbuk, and Shinan, Jeonnam in the glasswort field. Densities of Scrobipalpa salinella larvae were started to increase from mid-September in halophytes, such as Suaeda asparagoides, S. japonica, and S. maritima, rather than glasswort. S. salinella was overwintering inside the halophytes in old larva. Density ratio of overwintering S. salinella in Suaeda asparagoides, S. japonica, and S. maritima were 20.5, 28.4 and 51.1%, respectively. Overwintering population was highest in S. maritima among halophytes. The occurrence of first adult in the next spring was from April 19 to April 20 in Gimje, Jeonbuk, and Shinan, Jeonnam.