• Korean Journal of Veterinary Research
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• v.38 no.1
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• pp.107-117
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• 1998

The cultivation for development of Ascaris suum from the second-stage larvae($L_2$) embryonated egg and the third-stage of rat-derived larvae($L_3$) recovered from lung of rats were performed to use the screening test of anthelmintics in vitro. The preparations of larvae for cultivation were that the artificially-hatched $L_2$ incubated the embryonated eggs of Ascaris suum in 0.1% formalin solution at $25^{\circ}C$ for 28 days and the rat-derived larvae($L_3$) recovered from the lung of rat infected with the embryonated eggs of Ascaris suum on 7 days after infection(DAI). The cultivation for development of Ascaris suum from the embryonated eggs($L_2$) and the rat-derived larvae($L_3$) for 14 days in RPMI medium 1640(with 5% bovine calf serum) were as follows : 1. The sizes of the liberated larvae($L_2$) which were artificially hatched from embryonated eggs with glass beads(diameter 5mm) were $190{\sim}250{\mu}m$ on 1 days in culture(DIC). The second-stage larvae were molted into third-stage larvae(early $L_3$; $250{\sim}300{\mu}m$) and the features of these larvae were first observed such as cephalic cuticle, esophageal lumen and anus etc. on 5 DIC and the sizes of late third-stage larvae were $250{\sim}450{\mu}m$ on 10 DIC. The sizes of early fourth-stage larvae($L_4$) were $500{\sim}700{\mu}m$ and the features of these larvae were more pronounced in internal organs on 15 DIC. 2. The sizes of third-stage larvae($L_3$) recovered from the lung of rats were $1,340{\sim}1,370{\mu}m$ and the feartures of cephalic cuticle, esophageal lumen, intestine, rectum, anus were visualized by inverted microscope on 1 DIC. The fourth-stage larva($L_4$) completed by third ecdysis were recognizable and sizes of early fourth-stage larvae were developed as $1,400{\sim}2,200{\mu}m$ on 5 DIC. The sizes of middle fourth-stage of larva were $1,900{\sim}2,300{\mu}m$ and the thickened epithelial rectum was observed on 10 DIC. The rectum and anus of late fourth-stage larva($L_4$ $2,500{\sim}3,200{\mu}m$) had developed completely in RPMI medium 1640 on 15 DIC.

• Korean journal of applied entomology
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• v.44 no.2
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• pp.125-130
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• 2005

The ecological characteristics of the specialist insect predator, Oligota kashmirica benefica, were investigated for developing artificial rearing method with special interest on the oviposition behavior, the pattern of adult emergence and temperature in storage, and its effect on the density of the citrus red mite, Panonychus citri. Female beetle oviposited eggs mainly, $95\%$ of the eggs, on the bottom of leaves of the yuzu tree, and $91.3\%$ of them were covered with ecdysis skin of the red mites or the feces of themselves. The rate of adult emergence of the beetle rose up to $86.7\%$ when the horticultural media was provided for pupation from $60\%$ when it pupated in upland soil. Most larvae, $88\%$ of them, were found from the surface to the depth of 2 cm in the horticultural media. The optimum temperature for the storage of the adult beetle was found to be $12^{\circ}C$, at this temperature the 96.7, 73.3 and $70.0\%$ of the beetle survived for 10, 20, and 30 days, respectively. The control effect of the citrus red mite was appeared highest by releasing the beetle at the rate of one beetle against 150 mites.

• Journal of Sericultural and Entomological Science
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• v.20 no.2
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• pp.20-25
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• 1978

Research on the hormones of insect has followed by the special opportunities and problems arising from pollution. Since then, the main frame of it has been energetically exploited by ligation, decapitation and so on. In the meanwhile, knowledge of the biochemistry of hormone action as well as other aspects of biochemistry in insects has been gradually disclosed. Since 1966, practical use of active analogs of the hormones has been also worked out as an insecticide and brought the features of it to the light. On the other hand, it is expected to afford the increase of silk productivity resulted from control of the fifth larval period by delaying normal development. With these regards, some of analogs have been tried to apply practically to the silkworm. One of them is "Manta" produced by Zoecon Chemical Company and it is presently used for the increase of silk productivity in Japan. Another one is "R-20458", not registered one, issued by Stuffer Chemical Company. It is still pending for the silkworm growth regulator For the possibility of practical use, two chemicals are tested on the increase of silk productivity by topical application and the obtained results are summarized as follows. 1. It is evident that the fifth larval period was extended by topical application of the tested chemicals "Manta"and "R-20458"at the fifth instar after 51 hours of the last ecdysis, ranging from 12 hours to one day, as compared to. the control 2. In survival rates, there is no significance at 5% level between control and treatments. It proved that there was no toxity to silkworm by topical aprication. 3. There is an increase of cocoon yield in both chemical treatments. It was resulted from increase of weight of single cocoon. "Manta"2.5ppm produced 22.2kg of cocoon. It is equal to 9% increase in index, as compared to that of control. In case of R-20458, the increasing rates were varied at the different concentration; 21.4kg of cocoon production with 5% increase at 5ppm, 20.9kg of it with 2% increase at 2.5ppm and 20.6kg of it with 1% increase at 1. 25ppm in index, respectively, as compared with that of control. 4. Percentage of cocoon shell was increased by topical application. In case of "Manta" 2.5ppm, it is 25.6% which is equal to 6% increase in index, as compared with that of control. For "R-20458", the increasing rates of percentage of cocoon shell were varied with the different level of chemical concentration. They are 25.0% of 4% increase at 2.5ppm, 24.9% of 3% increase at 1.25ppm and 24.7% of 3% increase at 5ppm. 15% increase was attained at "Manta" 2.5ppm in the weight of cocoon layer based on cocoon yield and percentage of cocoon shell in index, as compared with that of control. The rates for "R-20458"are 5% increase at 2.5ppm and 4% increase at 1. 25ppm in index.

• Korean journal of applied entomology
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• v.61 no.1
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• pp.109-115
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• 2022

Vitellogenesis is the process by which yolk accumulates in developing oocytes. The initiation of vitellogenesis represents an important control point in oogenesis. When females of the model insect Drosophila melanogaster molt to become adults, their ovaries lack mature vitellogenic oocytes, only producing them after reproductive maturation. After maturation, vitellogenesis stops until a mating signal re-activates it. Juvenile hormone (JH) from the endocrine organ known as the corpora allata (CA) is the major insect gonadotropin that stimulates vitellogenesis, and the seminal protein sex peptide (SP) has long been implicated as a mating signal that stimulates JH biosynthesis. In this review, we discuss our new findings that explain how the nervous system gates JH biosynthesis and vitellogenesis associated with reproductive maturation and the SP-induced post-mating response. Mated females exhibit diurnal rhythmicity in oogenesis. A subset of brain circadian pacemaker neurons produce Allatostatin C (AstC) to generate a circadian oogenesis rhythm by indirectly regulating JH and vitellogenesis through the brain insulin-producing cells. We also discuss genetic evidence that supports this model and future research directions.

• Journal of Sericultural and Entomological Science
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• v.26 no.1
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• pp.25-29
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• 1984

Since 1966, practical use of active heavy analogs of the hormones has been also worked out as an insecticide and brought the features of it to the light as cocoon producer. On the other hand, it is expected to afford the increase of silk productivity resulted from control of the fifth larval period by delaying normal development. With these regards, some of analogs have been tried to apply practically to the silkworm for an increase of cocoon productivity. One of the synthesized juvenile hormone available is "Manina". And it is presently used for the increase of silk productivity in Korea. For the practical use, it is very essential the varietal differences in the increase of silk productivity by topical application was tested and the obtained results are summarized as follows. 1. It was evident that the fifty larval period was extended by topical application after 48 hrs. of the last ecdysis, ranging from 8 hrs. to one day, as compared to the control. 2. In pupal rates, there is no significance between control and treatments. It proved that there was no toxicity to silkworm by topical application in general, except jam 120. With regards to an increase of cocoon yield in Japanese, it was resulted from 17∼24% of cocoon yield from 10,000 larvae, as compared to that of control. In case of Chinese, the incrasing rates were varied from 15∼26% of cocoon yield, 17.8kg of it with 26% increase for Jam 122 and 16.7kg of it with 25% increase for Jam 118. In case of all hybrids, an increase of the cocoon yield took places from 20% to 31% and the weight of cocoon layer for the Japanese increased by 6 to 14%, those for the Chinese by 4 to 7% and those for the hybrids ranged from 21 to 29% increase. 3. It was recognized that the hybrid vigor rate took places with the hybrids between high responsing parents to juvenile hormones.

• Korean journal of applied entomology
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• v.48 no.4
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• pp.467-477
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• 2009

Host preference was tested on the 7 species plants against ggot-mae-mi, Lycorma delicatula (Hemiptera: Fulgoridae). This insect highly preferred Ailanthus altissima and Vitis vinifera however, didn't choose the other plants preferentially. Both nymphs and adults lived longest in A. altissima and V. vinifera but lived in short and low ecdysis rate against other plants and 3 species fruits. By analyzing the phloem-feeding behavior using EPG, L. delicatula was showed the short time in non-probing phase and it also exhibit the longest feeding time in A. altissima and V. vinifera, but other plants did not feed the phloem at all. In sugar contents analysis, A. altissima existed high sucrose proportion and followed by fructose>glucose, V. vinifera was analyzed by an order of glucose> fructose>maltose>sucrose>rhamnose, Malus pumila was as glucose> fructose, Pyrus calleryana was as glucose>unkown>fructose, Hibiscus syriacus was as sucrose>glucose. Nymphs and adults of L. delicatula lived longest in 5% sucrose solution, and next is in 5% fructose solution. However, they lived short in other sugar solutions. L. delicatula nymph and adult according to the combination of sugar proportion found in original plants lived longer in sugar combination solution of A. altissima and those of V. vinifera was next. Analyzed original sugar proportion from M. pumila, P. calleryana, H. syriacus respectively, L. delicatula lived short period comparing to the A. altissima, V. vinifera. This result was judged that sugar contents affected on choosing the host plants.

• The Korean Journal of Pesticide Science
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• v.18 no.3
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• pp.202-209
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• 2014

RNA interference (RNAi) is the method which controls phenotypes of gene in live cells. Chitinase is the enzyme helping digestion and absorption of old cuticles during the ecdysis of insects. In order to investigate molting-inhibition effect with the chitinase related gene in Spodoptera litura, RNA was extracted from the $5^{th}$ instars. cDNA was synthesized and then we obtained about 700 bp size chitinase. After PCR products were cloned into a pGEM T-easy vector, colonies were picked. DNA was extracted from the colony cultures. EcoR I enzyme was used to check whether PCR products were inserted or not. And then we confirmed vector band of about 3 kb and insert band of about 700 bp. To synthesize the dsRNA, each DNA was cut with Spe I and Nco I enzymes (Circular DNA became lineared DNA). After synthesis of dsRNA, approximately 5 ul dsRNA was injected into the $3^{rd}$ abdominal segment of S. litura $4^{th}$ larvae. The concentration of dsRNA was about $10{\mu}g/{\mu}l$. We confirmed larval-larval molting : there were phenotypically abnormal individuals - for instance malformation, molting inhibition and change of integument color. Pupaadult molting : there were phenotypically abnormal individuals - for instance molting inhibition, change of wings and malformation. Also we could investigate the pupation, emergence and variation about noninjection, treated with DW and dsRNA. Each pupation was non-injection 83.3%, DW 78.3% and dsRNA 66.7%. Each emergence was non-injection 90.0%, DW 72.3% and dsRNA 65.0%. So we considered that chitinase dsRNA induced molting inhibition effect. But each variation was non-injection 8.9%, DW 2.9% and dsRNA 19.2%. Therefore dsRNA group showed the highest variation value. When 18 hours after injecting dsRNA, we could obtain abnormal individual.