• Journal of Life Science
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• v.11 no.2
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• pp.121-125
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• 2001

Some attempts were made to investigate the biological characterisitcs of the green rice leafhopper(GLH) , Nepthotettix cincticeps Uhler in terms of nymphal development, emergence ratio. preovipositional period, growth index, adult longevity and fecundity fed on rice cultivar, Chucheongbyeo with no resistance gene and water foxtail, Alpecurus aequalis Sobol. var. amurensis Ohwi at 20 and $25^{\circ}C$ with a 16L;8D photoperiod. Development period of nymph on rice cultivar and water foxtail at $25^{\circ}C$ was shorter than that at 2$0^{\circ}C$ by twofold. The nymphal period of female was about one day longer than that of male. The mean emergence ratio of female and male on rice cultivar and water foxtail was 40.0, 76.7, 38.3, 73.3% at 20 and $25^{\circ}C$, respectively. Preovipositional period on rice cultivar and water foxtail at $25^{\circ}C$ was shorter that at 2$0^{\circ}C$ by twofold. Growth index on rice cultivar adn water foxtail at $25^{\circ}C$was higher than that at 2$0^{\circ}C$ by fourfold. Under the 20 and $25^{\circ}C$ condition, the longevity of female and male was longer on water foxtail than on rice cultivar, but the fecundity of GLH was higher on rice cultivar than on water foxtail. In conculsion, water foxtail seems to be adequate for spring host of GLH.

• Korean journal of applied entomology
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• v.22 no.4 s.57
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• pp.262-270
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• 1983

The newly hatched nymphs of brown planthopper(BPH) were reared individually for two generations in test tubes, where young rice seedling was planted on agar solution, at $30^{\circ}C,\;25^{\circ}C\;and\;20^{\circ}C\;with\;95\%,\;75\%,\;65\%\;and\;35\%$ R.H. Effects of $30^{\circ}C$ on the development of BPH when compared with those of $25^{\circ}C$ are followings. Egg period, nymphal period, and adult longevity were shortened. Nymphal mortality was increased and the number of oviposited eggs was decreased. Hatchability was zero per cent because the eggs were either unfertilized or died before finishing the development. At the low temperature of $20^{\circ}C$, in comparision with $25^{\circ}C$, the developmental period of nymphs and eggs was considerably lengthened, and adult longevity was shortened, the number of oviposited eggs was decreased. The nymphal mortality was higher at high relative humidity $(above\;75\%\;RH)$ than that at low relative humidity $(under\;65\%\;RH)$. Under the condition of high relative humidities, the adult longevity was shortened, and the number of oviposited eggs was decreased.

• Korean journal of applied entomology
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• v.43 no.2
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• pp.123-127
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• 2004

This study was conducted to determine the effect of food combinations of leguminous seeds on the nymphal development and adult fecundity of Riptortus clavatus Thunberg. Nymphal duration ranged from 20 to 28 days depending on food combinations with the shortest on the seed of soybean (Glycine max Linnaeus), soybean + kidney bean (Phaseolus vulgaris Linnaeus) and soybean ＋ peanut (Archis hypogaea Linnaeus) and the longest on the seed of kidney bean. Instar duration was longer with increasing instar from 2.4 to 2.5 days in the 1st instar to 5.3 to 7.3 days in the 5th instar Accordingly, instar duration was significantly different on food combinations exception of 1 st instar Percent emergence varied from 3.5％ on peanut to 65.0％ on the seed of soybean ＋ peanut. Nymphal mortality was the highest in the 1 st instar regardless of food combinations. Adult longevity was in range of 5.5 days to 11.2 days which was the shortest on the seed of kidney bean+peanut and the longest on soybean ＋ peanut and was about 8.0 days on the other food combinations. Total number of eggs laid by female was most on soybean+peanut and was least on kidney bean ＋ peanut. Accordingly, it can be recommended that food combination of the seed of soybean ＋ peanut was the best and then was soybean only while other food communications of leguminous seeds was hard to use for mass rearing of R. clavatus.

• Korean journal of applied entomology
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• v.12 no.4 s.17
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• pp.139-142
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• 1973

Experiment was conducted to study resistance of rice varieties and lines originated from Korea and IRRI-sources to the white-backed planthopper, Sogatella furcifera Horvath. The nature of varietal resistance to the insects was evaluated from the viewpoints of nymphal period and adult emergence. The varieties Colombia, Muthumanikam and Pankhari-203 were resistant, the varieties CO-22, Mudgo and Vellailangalayan moderately susceptible, the other varieties all susceptible. Nymphal period and rate of adult emergence were significantly different according to the degree of resistance of the rice varieties. Nymphal period was short (about 10 days) in the susceptible varieties and long (about 14-16 days) in the resistant varieties. The .ate of adult emergence was significantly lower in the resistant varieties than in the susceptible varieties. The lower rate of adult emergence in the resistant varieties may be due to the fact that the insects were suffered higher nymphal mortality in the resistant than in the susceptible varieties.

• Korean journal of applied entomology
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• v.29 no.3
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• pp.165-169
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• 1990

A study was carried out to investigate some biological characteristics of Pseudogonatopus nudas, a nymphal parasitoid of the whitebacked planthopper (WBPH) under laboratory conditions (26-$28^{\circ}C$). Developmental periods of eggs, larva, prepupa and pupa were 2.5, 7.8, 2.7, and 14.2 days in average, respectively. Total developmental period from egg to adult emergence was average of 27.2 days. More than 83.5% of the wasps emerged in the morning between 6 and 10 o'clock, while very few emerged in the afternoon. The average longevity of female and male were 11.8 and 3.4 days when honey and WBPH nymphs were supplied as food. female laid an average of 25.3 eggs and the oviposition period was 5.4 days. The parasitoid seemed to prefer the 3rd instar nymphas as the host for oviposition with 68.8%, followed by the 2nd (19.6%), 4th (11.05) and 5th instar (0.6%). And no parasitism was recorded from the 1st instar nymphs and in adults.

• Animal cells and systems
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• v.7 no.2
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• pp.105-109
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• 2003

Morphological characteristics of nymphal instars are described for a Korean wood-feeding cockroach, Cryptocercus kyebangensis. Eleven instars, including adults, were tentatively identified. Female adults had apicolateral emargination and a truncated apical median prominence in the seventh sternite, and female nymphs of the other instars except for the last had a narrowly rounded apical median prominence in the seventh sternite. In the last instar, the seventh sternite was partially desclerotized and somewhat shriveled at the start of the emarginated area. In contrast, males showed no emargination in adults, and had a rounded broad apical median in this area of all instars. In the ninth sternite, female nymphs had a medium notch on the caudal margin and styli were separated before reaching adulthood, whereas no such notch was observed in male nymphs. The styli remained prominent in the ninth sternite of male adults.

• Korean journal of applied entomology
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• v.17 no.4 s.37
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• pp.187-191
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• 1978

This experiment was conducted to determine the optimum temperature and day-length condition for laboratory multiplication of Green Rice Leafhopper, Nephotettix cincticeps Uhler, and to obtain basic information for deriving temperature dependent growth rate function. The insects which were reared in $33-35^{\circ}C$ have relatively short nymphal periods and high adult emergence rate compared with the insects which were reared in $27-29^{\circ}C$ The adults which emerged in $35^{\circ}C$ laid significantly smaller number of eggs than the adult reared in $27-29^{\circ}C$ during their nymphal stage. Day length in $29^{\circ}C$ did not have any influence to the nymphal growth, adult emergence rate and egg laying of the insect. The growth rate of the insect did not have linear relation with rearing temperature.

• Journal of Life Science
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• v.7 no.4
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• pp.347-354
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• 1997

Some attempts were made to investigate the gentic characteristics of the brown planthopper(BPH), Nilaparvata lugens Sta${\aa}$l, biotypes. In terms of egg and nymphal periods, egg hatcgability, emergence ratio, and population change of BPH and plant damage of rice cultivars by the infestation of BPH biotypes and their hybrid progenies in field conditions. The egg and nymphal periods of the three of BPH biotypes and their hybrid progenies on Dongjinbyeo with no resistance gene were shorter than on rice cultivars with resistance gene. But the periods of biotype-2(♀) X 2(♂) (E) on Samgangbyeo with Bph-1 gene and biotype-3(♀) X 3(♂)(I) on Mirying 63 with bph-2 gene were as short as on Dongjinbyeo. The egg hatchability and emergence ratio of the three Bph biotypes and their hybrid progenies on Dongjinbyeo were higher than on the other rice cultivars, and those of E on Samgangbyeo and I on Miryang 63 were as high as on Dongjinbyeo. In rice paddy field, biotype-1(♀) X 1(♂)(A)$\sim$I infested on Dongjinbyeo, E onSamgangbyeo, and I on Miryang 63 were increased their population densities remarkably in next generation. Dongjinbyeo infested by A$\sim$I, and Myryang 63 infested by I were hopperburned at 60 days after infestation and had a damage rating of 0.9. But Samgangbyeo infested by E was no hopperburn(damage rating: 7.3) though it showed high BPH population at 60 days after infestation.

• Korean journal of applied entomology
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• v.48 no.3
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• pp.311-318
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• 2009

Nymphal development, adult longevity, and oviposition of six different species of stink bugs were compared on seeds of a soybean cultivar, Taekwangkong, and two mung bean cultivars, Kyungseonnogdu and Jangannogdu in the insect rearing room ($28{\pm}2^{\circ}C$, 16L:8D). Nymphs of six species of stink bugs normally developed on Taekwangkong seed. While nymphs of Riptortus clavatus, Halyomorpha halys, and Dolycoris baccarum developed on seeds of Kyungseonnogdu and Jangannogdu normally, all nymphs of Plautia stali, Piezodorus hybneri and Nezara antennata died after 4th instars on Kyungseonnogdu and after 3rd instars on Jangannogdu. Each instar period tended to be increased as nymphal stages were progressed. Nymphal period was shortest on Taekwangkong seed, followed by Kyungseonnogdu and Jangannogdu, irrelevant to stink bugs species. Emergence rate, adult longevity, and preoviposition period of 6 stink bugs were different depending on the reared seeds. Of 6 different species examined, Riptortus clavatus, Halyomorpha halys, and Dolycoris baccarum which fed on Jangannodu did not emerge, Plautia stali, Piezodorus hybneri, and Nezara antennata which fed on Jangannodu did not oviposit.

• Korean journal of applied entomology
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• v.49 no.4
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• pp.305-312
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• 2010

The developmental time of immature stages of Paromius exiguus (Distant) was investigated at nine constant temperatures (15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5, $35{\pm}1^{\circ}C$), 20-30% RH, and a photoperiod of 14:10h (L:D). Eggs did not develop at $15^{\circ}C$, and their developmental time decreased with increasing temperatures. Its developmental time was longest at $17.5^{\circ}C$ (28.2 days) and shortest at $35^{\circ}C$ (5.9 days). The first nymphs failed to reach the next nymphal stage at 17.5 and $35^{\circ}C$. Nymphal developmental time decreased with increasing temperatures between $20^{\circ}C$ and $32.5^{\circ}C$, and developmental rate was decreased at temperatures above $30^{\circ}C$ in all stages except for the fourth nymphal stage. The relationship between developmental rate and temperature fit a linear model and three nonlinear models (Briere 1, Lactin 2, and Logan 6). The lower threshold temperature of egg and total nymphal stage was $l3.8^{\circ}C$ and $15.3^{\circ}C$, respectively. The thermal constant required to reach complete egg and the total nymphal stage was 109.9 and 312.5DD, respectively. The Logan-6 model was best fitted ($r^2$=0.94-0.99), among three nonlinear models. The distribution of completion of each development stage was well described by the 3-parameter Weibull function ($r^2$=0.91-0.99).