• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.526-532
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• 2017

Development, survival, and reproduction of brown planthopper (BPH) Nilaparvata lugens $St{\aa}l$ (Hemiptera: Delphacidae), were studied in laboratory at $25{\pm}2^{\circ}C$, $65{\pm}5%$ RH and a 16L : 8D hours photoperiodism on five rice cultivars of: Dongjin 1ho, Chungchungbyeo, Jangseongbyeo, Chinnongbyeo and Jungmo 1045. BPH nymphs successfully survived on all rice cultivars, although survival rate was lowest on Jangseongbyeo (36.0%). Developmental time of immature stages ranged from $11.7{\pm}0.59d$ on Jungmo 1045 to $12.8{\pm}0.59d$ on Chinnongbyeo. Reproductive period and female longevity were longest on Dongjin 1ho, Chinnongbyeo and Jungmo 1045 while highest fecundity of N. lugens being observed on these three rice cultivars. Highest and lowest net reproductive rates were calculated on rice cultivars, Jungmo 1045 and Jangseongbyeo, respectively. Mean generation time was the longest on rice cultivar Dongjin 1ho. Respective descending order of intrinsic rates of population increase were on Jungmo 1045, Chinnongbyeo, Dongjin 1ho, Chungchungbyeo and Jangseongbyeo. These population parameters showed that N. lugens can successfully survive and reproduce on Chinnongbyeo and Jungmo 1045.

• Korean journal of applied entomology
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• v.61 no.3
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• pp.423-434
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• 2022

The two previously developed artificial diets (N4 and N6) used for rearing Spodoptera frugiperda (Noctuidae) larvae, were selected as highly-fit ones for rearing Mythimna loreyi larvae. Almost all biological characteristics were not significantly different between the colonies reared on the two diets at 25℃ and 15:9 h (light:dark) photoperiod. The developmental periods were 4.9-5.2 days for eggs, and 22.3-23.2 days for larvae. The pupal period and weight were different between the sexes in each diet colony. The pupal periods in females and males showed 12.6-12.8 days and 14.1-14.5 days, respectively. The pupal weights were ca. 345 mg for females and ca. 380 mg for males. The pupation and emergence rates were ca. 91-94%, and ca. 91-95%, respectively, without significant differences between the two colonies. The pre-oviposition and oviposition periods were 3.4 days and 4.7-4.8 days, respectively. The adult longevity was 8.2 days in females and 10.3-12.4 days in males. Total offsprings produced were found to be 724-847 larvae on an average with ca. 1,400 maximum larvae. In the life table analysis, the intrinsic rates of increases (0.1181 for N4 and 0.1253 for N6) were not significantly different between the two colonies. Individual differences in the larval instar number 5 and 6 were found within a diet colony. The ratios of 5-instar larvae were ca. 22% in N4 colony and ca. 7% in N6 colony. The larval period of 6-instar larvae was longer than that of 5-instar larvae. Width of head capsule in larvae varied from ca. 309 ㎛ for 1st instar to ca. 3,065 ㎛ for 6th instar. Body lengths measured from ca. 2.0 mm for 1st instar to ca. 29.1 mm for 6th instar. Larvae of M. loreyi and M. separata were found at the same time in a maize field during June and July, 2020.

• Korean journal of applied entomology
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• v.26 no.1 s.70
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• pp.13-23
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• 1987

This study was conducted to know the effects of temperature conditions on the growth and oviposition of the brown planthopper(BPH), Nilaparvata lugens $St{\aa}l$. Results obtained were to predict the timing of the BPH control by measuring population dynamics of the BPH in response to temperature fluctuations upon migration of the insects in paddy fields. Developmental and ovipositional rates under constant and alternating temperature conditions were observed in a plant growth cabinet. Hatchabilities of eggs of the BPH were the highest at $25^{\circ}C$ and were decreased below or above the optimum temperature. Egg periods were the shortest at $27.5^{\circ}C$ and prolonged with decreasing temperature, but retarded at higher temperature above $30^{\circ}C$. Adult emergence rates were the highest at $27.5^{\circ}C$ and reduced with decreasing temperature, and no adult emerged at $32.5^{\circ}C$ and $35^{\circ}C$. Developmental period of nymph was the shortest at both $27.5^{\circ}C$ and $30^{\circ}C$, but extended with decreasing temperature. Female longevity was increased with decreasing temperature and the male longevity was the shortest at $27.5^{\circ}C$. Preoviposition period was the shortest at $32.5^{\circ}C$, but prolonged with decreasing temperature. It was about 6.5 times longer at $17.5^{\circ}C$ than that at $32.5^{\circ}C$. Number of eggs oviposited per female was the greatest at $25^{\circ}C$, but decreased at the temperature below or above the optimum. Under the same total effective day-degrees, hatchabilty at the alternating temperature was about 10% higher than that at the constant temperature but egg period at the alternating temperature was nearly identical as that at the constant. Under the $22^{\circ}C$ condition, emergence rate was about 8% higher at the alternating temperature than that at the constant, however, at the $28^{\circ}C$, the rate was about 8% higher at the constant than that at the alternating. Nymphal period was about $4{\sim}6$ days longer at the alternating temperature than that at the constant. Under the same total effective day-degrees in adult stage, both longevity and oviposition period were longer at alternating temperature than those at the constant. Number of eggs oviposited per female was also higher at the alternating. Longevities of females reared under $28^{\circ}C$ of constant temperature was the longest no matter what temperatures they were exposed after the emergence. This result seems to be indicating that female longevity is greatly influenced by the temperature to which they were exposed durings immature stages. Preoviposition period was affected by the temperature exposed during the nympal and adult stage whereas the number of eggs oviposited was affected by the temperature during the adult stage only. Based on the results from this study, the developmental threshold temperatures seem to be $14.12^{\circ}C$ for eggs, $14.76^{\circ}C$ for nymphs, $9.62^{\circ}C$ for adults, and $15.95^{\circ}C$ for preoviposition period. Estimated values of the total effective temperature for completing each stage were 141.25 day-degrees for eggs, 167.83 day-degrees for nymphs, 349.64 day-degrees for adults, and 58.60 day-degrees for preoviposition.

• Reproductive and Developmental Biology
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• v.31 no.1
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• pp.35-41
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• 2007

This study was conducted to examine the effects of energy substrates in different conoentration of carbohydrates in the human oviduct and uterus on the in vitro development of mouse 2-cell embryos. Two-cell embryos were collected from ICR female mice at $46{\sim}50\;hr$ after 5 IU hCG injection and cultured in three different media [control: 0 mM, Guoup A: glucose (G) 0.5 mM + pyruvate (P) 0.32 mM + lactate (L) 10.5 mM, Group B: G 3.15 mM + P 0.1 mM + L 5.83 mM] for 72 hr. Rates of morula formation of group A (72.3%) and B (56.6%) were significantly higher higher (p<0.05) than that of control (34.9%) at 24 hr. However, blastocyst rate was significantly higher (p<0.05) in control (51.8%) than group A (39.8%) and B (28.9%) at hr. At 72 hr, no differences were found in the number of zona-intact, zona-escape and total blastocysts among groups. Mean and ICM cell numbers were significantly higher (p<0.05) in group A (78.0, 13.4) and B (64.4, 11.8) than control (53.1, 5.7), respectively, The percent of ICM were significantly higher (p<0.05) in group A (22.9%) and B (23.7%) than control (14.2%). No differences were round in the TE cell numbers ($34.1{\sim}45.1$). The ICM:TE ratio was significantly higher $34.1{\sim}45.1$ in control (1:6.0) than group A (1:3.4) and B (1:3.4). This study shows that energy substrates added to culture media especially, the oviductal level of carbohydrates increase the developmental capacity of 2-cell mouse embryos.

• Korean journal of applied entomology
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• v.40 no.3
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• pp.203-209
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• 2001

Development and reproduction of the sweetpotato whitefly, Bemisia tabaci(B biotype) were investigated under different temperatures and host plants. Developmental periods from egg to pre-adult of whiteflies measured under four constant temperatures: they were 86.2 days at $15^{\circ}C$ and 17.0 days at $30^{\circ}C$. Lower threshold temperature and total effective temperature for the development of egg and nymph, and for the complete development (egg to emergence) were $10.1,\;11.6,\;11.1^{\circ}C$ and 110.3, 204.7, 317.3 degree days, respectively. The hatching and emergence rates were 87.0% at $25^{\circ}C$ and 76.7% at $20^{\circ}C$, which were higher than the results of other temperatures. The adult longevity was 23.6 and 14.0 days at $20^{\circ}C$ and $30^{\circ}C$, respectively. The highest average fecundity per female was 103.3 at $25^{\circ}C$. But there were no significant differences among the temperatures. The highest intrinsic rate of natural increase($r_{m}$) was 0.196 at $30^{\circ}C$ and the highest net reproduction rate ($R_{o}$) was 97.33 at $25^{\circ}C$. Developmental periods from egg to pre-adult of whiteflies were 21.2 on the tomato, 28.1 on red pepper, 22.2 on eggplant and 25.5 days on poinsetia. The hatching was highest (90.3%) on red paper and emergence rate was highest (89.6%) on eggplant. The longest longevity of adult female was 26.5 days on eggplant, and the average fecundity per female was greater on tomato and eggplant than on other host plants. The intrinsic rate of natural increase($r_{m}$) was the highest on tomato as 0.165 and the net reproduction rate ($R_{o}$) was the highest on eggplant as 106.1. As a result, the optimum range of temperature for the growth of B. tabaci was between $25^{\circ}C$ and $30^{\circ}C$, and the optimum host plant were tomato and eggplant among the plants tested.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.1
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• pp.55-65
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• 1999

There have been many reports to date regarding the role of GnRH as a local regulatory factor of ovarian function as studies of human and rat ovaries revealed GnRH and its receptor. In recent studies it has been shown that GnRH directly causes apoptosis in the granulosa cells of the rat ovary, and such results leads to the suggestion that the use of GnRH agonist for more stable long term ovarian hyperstimulation in human IVF-ET programs causes granulosa cell apoptosis which may lead to follicular atresia. Therefore this study attempts to determine if granulosa-luteal cell apoptosis occurs in patients during IVF-ET programs in which GnRH agonist is employed for ovarian hyperstimulation. The quality of oocyte-cumulus complexes obtained during ovum pickup procedures were assessed morphologically and then the fertilization rate and developmental rate was determined. Apoptotic cells among the granulosa-luteal cells obtained during the same procedure were observed after staining with Hematoxylin-eosin. The fragmentation degree of DNA extracted from granulosa-luteal cells was determined and comparatively analyzed. There was no difference in the average age of the patients, the number of oocytes retrieved, and fertilization and developmental rates between the FSH/hMG group and GnRH-long group. There was also no difference in the apoptosis rate and pyknosis rate in the granulosa-luteal cells between the two groups. However, when the oocyte-cumulus complexes were morphoogically divided into the healthy group and atretic group without regard for the method of hyperstimulation, the results showed that the number of oocytes obtained averaged $11.09{\pm}8.75\;and\;10.33{\pm}4.53$ per cycle, respectively, showing no significant difference, but the fertilization rate (77.05%, 56.99%, respectively, p<0.01) and developmental rate (65.96%, 41.51%, respectively, p<0.01) was significantly increased in the healthy group when compared to the atretic group. The degree of apoptosis in the granulosa-luteal cells showed that in the healthy group it was 2.25% which was not significantly different from the atretic group (2.77%), but the pyknosis rate in the atretic group (27.81%) was significantly higher compared to the healthy group (11.35%, p<0.01). The quantity of DNA fragmentation in the FSH/hMG group was 32.22%, while in the GnRH-long group it was 34.27%, showing no significant difference. On the other hand the degree of DNA fragmentation was 39.05% and 11.83% in the healthy group and atretic group, respectively, showing significantly higher increase in the atretic group (p<0.01). The above results suggest that death of granulosa-luteal cells according to the state of the oocyte-cumulus complex is more related to pyknosis rather than apoptosis. Also, the GnRH agonist used in ovarian hyperstimulation does not seem to directly affect the apoptosis of retrieved oocytes and granulosa-luteal cells, and which is thought to be due to the suppression of the apoptogenic effect of GnRH agonist as a result of the high doses of FSH administered.

• Korean Journal of Animal Reproduction
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• v.24 no.4
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• pp.365-373
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• 2000

The purpose of this study was to investigate the effects of the fusion pulses and fusion media on fusion rate and the development of embryos produced by somatic cell nuclear transfer in Hanwoo (Korean cattle). Nuclear donor cumulus and fetal fibroblast cells were cultured in Dulbecco's modified Eagle medium supplemented with 10% fetal bovine serum at 38.5$^{\circ}C$ in a humidified atmosphere of 5% $CO_2$in air. The in vitro matured oocytes were enucleated and then the isolated donor cells were introduced. The cumulus cell and cytoplast were fused using one pulse of 70 volts for 40$mutextrm{s}$, two pulses of 70 volts for 40$mutextrm{s}$ and one pulse of 180 volts for 15$mutextrm{s}$. The fetal fibroblast cell and cytoplast were fused using one pulse of 180 volts for 15$mutextrm{s}$ or 30$mutextrm{s}$. The cumulus cell and cytoplast were fused using mannitol and Zimmerman cell fusion medium (ZCFM) as a fusion medium. The fused embryos were activated after the fusion with 10 $\mu$M calcium ionophore for 5 min and 2 mM 6-dimethyl- aminopurine for 3 h. The nuclear transfer embryos were cultured in 500 ${mu}ell$ well of modified CR1aa supplemented with 3 mg/$m\ell$ BSA in th $\varepsilon$ four well dish cove red with mineral oil. After 3 days culture, culture medium was changed into modified CRlaa medium containing 1.5 mg/$m\ell$ BSA and 5% FBS for 4 days. The incubation environment was 5% $CO_2$, 5% $O_2$, 90% $N_2$ at 38.5$^{\circ}C$. When the cumulus cells were fused with enucleated oocytes by three different fusion pulses, one pulse of 180 volts for 15 $mutextrm{s}$ yielded the highest fusion rate and developmental rate to blastocyst among the pulses (P＜0.05). When the fetal fibroblast cells were fused with enucleated oocytes, one pulse of 180 volts for 30$mutextrm{s}$ yielded significantly higher fusion rate compared with that for 15 $mutextrm{s}$(P＜0.05). The present result indicates that the fusion rate between karyoplast and cytoplast was affected by the cell type and the optimal fusion condition was different according to cell type or size. When the fusion was conducted by the use of mannitol and ZCFM, the fusion rate was 71.2% and 65.8%, respectively. The developmental rates to blastocyst were 37.8% and 39.8%, respectively. There was no significant difference between two fusion media in the developmental rate of cumulus cell nuclear transfer embryos. These results indicate that optimal electric current should be selected according to cell type.

• Journal of Embryo Transfer
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• v.21 no.4
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• pp.299-306
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• 2006

This study examined the effects of the in vitro produced (IVP) Hanwoo blastocyst stage (blastocyst, expanded blastocyst and hatched blastocyst), in vitro culture day (7, 8, and 9) and blastocyst grade (1, 2 and 3) on the pregnancy rate, gestation length, birth weight, the incidence of dystocia and twining rate after embryo transfer (ET). The pregnancy and abortion rates were significantly higher in the blastocyst (B) stage (64.4%) and in the hatched blastocyst (HB) stage (21.4%), respectively, than in those of the other developmental stages (p<0.05). The pregnancy rate of Day 7 embryos (49.0%) was significantly higher than those of Days 8 and 9 embryos (36.4 and 15.4%), but the abortion rates were similar (0 to 10.7%). There were no significant differences in the pregnancy (41.4 to 42.5%) and abortion (9.3 to 16.5%) rates among the three grades of embryos. There were no significant differences in gestation length, birth weight and the incidence of dystocia among the three development stages, but the twinning rate was significantly higher in the HB stage (p<0.05). The pregnancy rate, the incidence rate of dystocia and twinning rate were similar among the three different culture days, however birth weight was significantly heavier in calves from Day 9 embryos than in those from Days 7 and 8 embryos. The mean gestation length of grades 1 and 2 embryos (278.5 and 276.1 days) were significantly longer than that of grade 3 (p<0.05), but birth weight, the incidence of dystocia and twinning rate did not significantly differ. The mean gestation length in single calves was significantly longer than that in twin calves (278.5 vs. 272.5 days, p<0.05). In addition, the mean birth weight in single calves was significantly greater than that in twin calves (29.6 vs. 22.3 kg, p<0.05). Finally, the sex ratios and mean mortality rates between single and twin calves were similar.

• Korean Journal of Animal Reproduction
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• v.20 no.2
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• pp.119-126
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• 1996

This study was carried out to determine the optimal condition for successful and efficient c cryopreservation of zygotes, 1-cell embryos, using EFS40 which was 40% (v/v) ethylene glycol diluted in DPBS medium containing 30% Fic-oll (w/v) and 0.3 M sucrose. After mouse zygote produced by IVF was vitrified by two freezing methods, the post-warming survival rates of 1-cell zygotes were assessed as cleavage to the 2-cell stage and development into the hatching blastocysts at 5 day. In the one-step method, when embryos were directly exposed to the vitrification solution at 25$^{\circ}C$ for 1 min., survival and development rates of zygotes were 85.5% and 31.9% In the two-step method, embryos were equilibrated with a dilute 20% EG for 1, 3, 5 min. before 1 min. exposure to EFS40, re-spectively. However, the rates of development (17.7, 3.3, 0%) were lower than that of one-step method. The highest survival rate (95.9%) was obtained by one-step method which exposes embryos in EFS40 for 30 sec. In this condition, 63. 8% of cleaved 2-cell developed into hatching blastocysts. In the cell number of Total and ICM using differential labelling technique, there are no significant differences in the cell number of Total and ICM between blastocysts devel oped in vitrified-thawed embryos (63.2${\pm}$16.9, 1 13.5${\pm}$4.0) and control balstocysts (54.0${\pm}$15.2, 1 12.3${\pm}$4.6). Therefore, these results show that mouse zygotes can be successfully cryopreserved by a simple vitrification method although developmental rates of vitrified embryos were reduced. In conclusion, this proposed vitrifi cation procedures can be useful in the cryopreservation of mouse IVF zygotes.

• Korean Journal of Animal Reproduction
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• v.22 no.1
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• pp.11-17
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• 1998

This study was carried out to investigate the in vivo developmental potential of mouse zona-hatched blastocysts (HBs). The HBs were cultured in vitro until day 5 and day 6 from zygotes produced in vivo and classified to small (S-HBs), medium (M-HBs) and large (L-HBs) on the basis of embryo diameters. The results obtained in these experiments were summarized as follows ; 1) when the blastocysts at day 4 were further cultured for $24\sim48hr$, HBs obtained at day 5 and day 6 culture in vitro were 29.1% and 22.8%, respectively. 2) Also, when the total cell number of HBs were counted, cell numbers of classified HBs on day 5 and day 6 to small ($77.3\pm5.3$, $59.6\pm4.4$), medium ($83.7\pm4.0$, $66.8\pm3.5$) and large ($100.7\pm2.6$, $88.9\pm3.8$) were increased as their size increases. Especially, there were significantly different between S-HBs and L-HBs (p<0.01). 3) In addition, when the classified HBs were transferred into when the classified HBs were transferred into day 3 pseudopregnant recipients, the pregnancy and implantation rates of S-HBs (28.6%, 15.7%), M-HBs (44.4%, 30.9%) and L-HBs (62.5%, 49.1%) at day 5 were increased as their size increases. However, this pattern was not showed in embryo transfer of day 6 HBs. But, when the live fetuses formation against total implantation rates were observed, the result (87.5%) of S-HBs of day 5 was significantly higher than that of the others (p<0.01). Therefore, this study demonstrates that in vitro cultured healthy HBs can not only be developed normally with good pregnancy rates, implantation rates and live fetuses formation, but also served as a fundamental data for utility of supernumerary HBs in human blastocyst transfer.