• Korean journal of applied entomology
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• v.61 no.4
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• pp.555-562
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• 2022

We raised the white-spotted flower chafer, Protaetia brevitarsis seulensis, from the larvae stage using a fermented mulberry sawdust-base diet at 25℃ and 16:8 h light:dark photoperiod. First, we determined the optimal density of the neonate larvae to be introduced into a rearing box (543 × 363 × 188 mm). The survival rates of the larvae were higher than 80% at 90 days after rearing at 100-175 larval densities but reduced by more than 10% at 200 larval density. The larval weights at 100 to 150 larval densities were similar; however, the weights at 175 and 200 larval densities were lower than those at 100 larval densities, indicating that the rate of weight gain increased under lower density. Based on these results, we inferred that 100-150 larvae was the optimal density. Second, we investigated the storage conditions of the last instar larvae under low temperatures. Four weight groups (1.8-2.0, 2.0-2.3, 2.3-2.5, and 2.5 g) of larvae were stored at 4, 8, and 10℃, respectively. All the larvae at 4℃ died 70 days after storage, whereas 80% of the larvae survived at 8℃ 70 days after storage, indicating that high larval weight was associated with high survival rates. The adults that emerged from larvae with more than 2.3 g and stored for up to 50 days at 4℃ laid few eggs. However, the adults that emerged from all larval weight groups stored for 70 days at 8℃ and 10℃ laid several eggs successfully. Based on these results, we inferred that the last instar larvae with more than 2.3 g could be stored for 30-50 days at 8℃.

• Korean journal of applied entomology
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• v.62 no.4
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• pp.315-323
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• 2023

The brassica leaf beetle, Phaedon brassicae Baly (Coleoptera: Chrysomelidae), is one of the important pests infesting cruciferous vegetables. In order to understand the biological characteristics of the insect, we investigated the effects of temperature on development of each life stage, adult longevity and fecundity of P. brassicae at four constant temperatures of 15, 20, 25 and 27.5℃ for immature life stage and five constant different temperatures of 10, 15, 20, 25 and 27.5℃ for adult stage. Eggs and larvae successfully developed next life stage at temperature tested. The development period of egg, larva, and pupa decreased as temperature increased. Lower developmental threshold (LDT) and thermal constant (K) were calculated using linear regression as 8.7℃ and 344.73DD, respectively. Lower and higher threshold temperature (TL and TH) from egg to adult emergence were estimated by Briere function as 5.3℃ and 40.4℃, respectively. Adults produced eggs at the temperature range between 10℃ and 27.5℃, and showed an estimated maximum number, ca. 627.5 eggs at 21.7℃. Adult oviposition models including aging rate, age-specific survival rate, age-specific cumulative oviposition, and temperature-dependent fecundity were constructed. Temperature-dependent development models and adult oviposition models would be useful components to understand the population dynamics of P. brassicae and to establish the strategy of integrated pest management in cruciferous crops.

• Journal of Aquaculture
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• v.9 no.3
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• pp.287-291
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• 1996

[ $F_2$ ] generation of gynogenetic diploids were produced in olive flounder, Paralichthys olivaceus, by brother-sister mating with full-sibling gynogenetic diploids ($F_1$). The induced ovulations and spawnings were conducted by using intraperitoneal injections of HCG (2,000 IU/kg body weight) with photoperiod controls. Floating rates of artificially ovulated eggs were ranged from 22.9 to $65.7\%$. Fertilization and hatching rates were ranged from 69.0 to $86.2\%$ and 36.8 to $85.8\%$, respectively. All of those three rates between two experimental groups were not significantly different (P>0.05). Average survival rates of $F_2$ generation of 40-day-old 효nogenetic diploid larvae were slightly lower than those of controls (P<0.05), however growth rates were much higher than those of their diploid controls.

• The Korean Journal of Pesticide Science
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• v.4 no.4
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• pp.40-47
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• 2000

The comparative toxicity of ten acaricides, seven insecticides and five fungicides to the two-spotted spider mite, Tetranychus urticae and its predators, Amblyseius womersleyi and A. eharai was evaluated by a leaf spray bioassay. Five of the acaricides tested, bifenazate, etoxazole, acequinocyl, flufenoxuron and chlorfenapyr were much less toxic to adult females of A. womersleyi and A. eharai than to T. urticae adult females. A. womersleyi adult females treated with five acaricides produced $52{\sim}93%$ as many eggs as untreated adult females. And A. eharai adult females treated with five acaricides laid $54{\sim}73%$ as many eggs as untreated adult females. The remaining acaricides showed high toxicity to adult females of A. womersleyi and A. eharai. All the insecticides tested were less toxic to T. urticae adult females than to adult females of A. womersleyi and A. eharai. However, tebufenozide and diflubenzuron did not significantly affect the survival and reproduction of adult females of A. womersleyi and A. eharai. All the fungicides tested showed low mortality (${\leq}24%$) to adult females of predatory mites. However, benomyl had significant effect on the reproduction of adult females of A. womersleyi and A. eharai. Four acaricides (bifenazate, acequinocyl, flufelloxuron and chlorfenapyr) were much less toxic to eggs of A. womersleyi and A. eharai than to T. urticae eggs. However, etoxazole caused relatively low hatchability ($58{\sim}62%$) of eggs of A. womersleyi and A. eharai. All the insecticides and fungicides tested did not significantly affect the hatch of eggs of predatory mites. It may be suggested from these results that four acaricides, two insecticides and four fungicides described could be Incorporated into the integrated mite management system with A. womersleyi and A. eharai in pear orchard.

• The Korean Journal of Pesticide Science
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• v.6 no.4
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• pp.257-263
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• 2002

This study was carried out not only to investigate the toxicities of 12 registered insecticides on different developmental stages, but also to determine the sublethal effects on longevity and reproduction of newly emerged adult female and development of the next generation in the rice skipper, Parnara guttata. Fenitrothion, fenthion, cartap hydrochloride, ethofenprox highly suppressed egg-hatch. All insecticides treated showed high larvicidal activity on the 1st to 2nd instar larva. The insecticides showed higher larvicidal activities on the 5th instar larva were fenitrothion, fenthion, ethofenprox, fipronil, methoxyfenozide, tebufenozide and Bt. var. kurstaki. The sublethal doses of fenthion, tebufenozide, cartap hydrochloride, methoxyfenozide, ethofenprox, imidacloprid and fipronil shortened the longevities of newly emerged adult female from the treated larva ($3{\sim}4$ instar). BPMC, imidacloprid, ethofenprox, fipronil and methoxyfenozide delayed the preoviposition periods of adult females and decreased the number of eggs laid when they were treated at the larval stages of the previous generation. Ethofenprox caused severe sublethal effects on P. guttata offspring, completely blocking the production. All insecticides except fenitrothion affected the egg viability, and all eggs from the adult females emerged from the survivors treated larvae with imidacloprid or fipronil fail to hatch. IGRs, methoxyfenozide and tebufenozide showed an adverse effect on the development of next generation larva.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.43-55
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• 1976

Fertilization and early development of turbo cornutus was studied based on the samples which were collected in Yeosu area. Particular emphasis was paid on induction of artificial spawing, fertilization rate, preembryonic development, the growth of the early larva and larval survival to various salinity. Among the various methods for induction of artificial spawning which have been tested for the present study, drying by exposure to air is the. most efficient, and percentage fertilization rate was $83.8-96.4\%$. The diameter of fertilized eggs was $0.182{\pm}0.0028mm$; and the diameter of egg membrane was $0.245{\pm}0.093mm$. Under the temperature range of $20.6-25.4^{\circ}C$ the larvae hatched out after 11:05-11:15 hours of fertilization. After 3.0-3.5 days of fertilization the planktonic larvae begand to settle, and the settlement terminated within 5 days. During the period of 150 days of early culturing the diameter growth of shell(M) and the diameter of shell aperture(A) was formulated as follows: $$1972\;M=0.33e^{0.02070D}$$ $$A=0.19e^{0.02282D}$$ $$1973\;M=0.32e^{0.02282D}$$ $$A=0.16e^{0.02596D}$$ During the same period of early culturing the relative growth of shell diameter and the diameter of shell aperture was formulated as follows : 1972 A=0.6478 S-0.1575 1973 A=0.5897 S-0.0515 After 11 days of larval hatching $0.02-0.18\%$ of planktonic larvae settled. After 150 days of settlement the survival rate of the early shells was $7.4-21.6\%$. Under the temperature range of $21.0-22.7^{\circ}C$ the optimum salinity range for the development of egg and the planktonic larvae was $30-35\%_{\circ}$.

• Korean journal of applied entomology
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• v.58 no.4
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• pp.381-387
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• 2019

From 2017 to 2019, the ovipositional and the developmental characteristics of Gampsocleis ussuriensis Adelung in the Buan area of Jeonbuk Province were examined. G. ussuriensis were mostly found in the weeded areas around the reservoir, where the adults first appeared in mid-July, showed up where by the early September, and overwintered in eggs. Nymphs appeared in early April to mid-July the next year. The nymphs hatched from early April and adults appeared after molting five times. The ovipositional period of G. ussuriensis was approximately 58 days. The total number of eggs per female was 124. The mean longevity of adults was 95.6 days for females and 84.8 days for males. Ovipositional mats were best with mixed Masato and Coco-Pitt at a ratio of 7:3. Developmental period of G. ussuriensis nymphs was 64.1 days at 24℃ and was longer than at different temperatures. The higher the temperature, the shorter the developmental period. The survival rate of nymphs was the best at 32℃ in 77.8%. The higher the density while rearing, the lower the survival rate, and the faster the development and molting velocity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.5
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• pp.481-486
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• 2009

In 2007, 43.5% mortality of the cultured oyster population occurred in Gamak Bay. Mortality rapidly increase in September and peak in October. To prevent future mass-mortality event, we investigated spawning and variation of oyster body composition. The main spawning period of culture oyster occurred from August to September. Condition index and body composition (protein and glycogen) appeared to be influenced by the spawning activity. Condition index and glycogen content in September were lowest (13.5% and 5.6 mg/g, respectively). However, protein, lipid and glycogen contents did not rapidly recover after the spawning activity. The data indicates that mass-mortality of cultured oysters in Gamak Bay may be due to deteriorated health, spawning activity, stress of the high water temperature and decreasing food resources.

• Journal of Sericultural and Entomological Science
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• v.6
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• pp.49-52
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• 1966

It has been reported that the effect of royal jelly on silkworms can be markedly resulted from feeding on royal jelly throughout all the instars. In 1965, I began the experiment in order to know whether it has a practical for rearing, only through feeding silkworms at 1st to 2nd instar, when a comparative little amount of mulberry leaves and labor is needed for rearing. In the method of my experiment, mulberry leaves with different concentration of royal jelly added, 2.5%, 5%, and 10%. respectively, are feeded on silkworms of Sulack ${\times}$ Soyang at 1st and 2nd instar in spring in 1965. However, in the result of the experiment there is not any effect on the survival. the growth speed, the body weight, of the larvae, and the weight of cocoon layer, the cocoon layer ratio, and number of silkworm eggs laid.

• Korean Journal of Environmental Biology
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• v.22 no.1
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• pp.159-166
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• 2004

The effects of polychlorinated biphenyls (PCBs) on the reproduction of the oily bitterling, Acheilognathus koreensis were investigated using histological methods. The experimental fishes were exposed to 0. 3.4, 9.3 and 25.8 ${\mu}g\; L^{-1}$ PCBs fey 8 weeks. Dead fishes and abnormal behavior were not observed in control and PCBs exposure group. In compared with control group, PCBs exposure fishes showed differences of gonadal development, gonadosomatic index (GSI), hepatosomatic index (BSI), nuptial color index (NCI) and ovipositor length index (OLI). These results showed that PCBs could disrupt reproductive process in the fish.