• International Journal of Industrial Entomology and Biomaterials
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• v.11 no.1
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• pp.79-79
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• 2005

• Korean journal of applied entomology
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• v.31 no.4
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• pp.366-370
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• 1992

Salient chromosomal variations during the first meiotic division in primary spermatocyLes of the three brown planthopper, Nilaparvata lugens (Stal) , biotypes were observed. The meiotic index was highest in biotype 3 (58.6), followed by biotype 1 (39.4) and biotype 2 (23.6). Total chromosomal aberration including agmatoploidy, aneuploidy, loose pairings of sex chromosomes, and cytoplasmic shrinkage was found high in the order of biotype 1 (60.6%),2 (47.9 %), and 3 (38.1 %). However, percent agmatoploidy was highest in biotype 2 (19.6%) whereas in biotypes 3 and 1, it was 9.5% and 2.5%, respectively. The number of cells with isolated sex chrosomomes was observed highest in biotype 2.

• International Journal of Industrial Entomology and Biomaterials
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• v.10 no.2
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• pp.137-141
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• 2005

Though many insecticides are commercially available, development of resistance, pest resurgence and effects on non-target organisms led to the search for alternate insect pest management (IPM) strategy based on larval growth and reproductive fitness. Reproductive potential of insects depends on its acquiring of vitellogenic competence which is under hormonal control. Exogenous application of analogues of JR (JHAs) and ecdysterone could derail normal development and reproduction in insects by manipulating an array of physiological processes. In the rice pest, brown planthopper, Nilaparvata lugens, JHA, hydroprene induced metathetely from the fifth (final) instar nymphs in an age-dependent manner. Day 0 of the final instar showed highest sensitivity to induce this abnormal development. Adults emerged from treated day 3 nymphs looked normal. Both the morphotypes were reproductively incompetent and showed partial to complete sterility. Pre-adult exposure of the ovarian tissue to hydroprene suppressed mitotic division of germinal cells and induced abnormalities in the later s1ages of growth and differentiation of ovary in N. lugens. More over the nymphal exposure to hydroprene inhibited patency changes of follicular epithelium and affected competence of the follicles for yolk sequestration. In the absence of ovarian growth and oocyte differentiation, germarium found disintegrated, trophic core regressed and terminal oocytes resorbed. Hydroprene exposure to newly ecdysed brachypterous females did not affect ovarian development and egg production. Proper larval-adult transition appeared as a. prerequisite for vitellogenic competence in N. lugens for which the ovarian tissues must be exposed to ecdysterone in the internal milieu devoid of JH.

• Proceedings of the Korean Society of Crop Science Conference
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• 2000.04a
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• pp.376-377
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• 2000

• Korean journal of applied entomology
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• v.42 no.4
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• pp.361-365
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• 2003

Several species of planthoppers such as brown planthopper, N. lugens (Stal) (BPH), smaller brown planthopper, Laodelphax striatellus (Fall n) (SBPH), and white-backed planthopper, Sogatella furcifera (Horv th) (WBPH) are distributed in Korean rice paddies but not easy to discriminate them in situ. Accurate discrimination of them is an indispensable process in the forecasting for their outbreak and control. Especially, innovative discrimination method for BPH was required because BPH was one of the most important insect pest of rice. Nymphs and adults of BPHs, SBPHS, and WBPHS, thus, were examined their morphological characteristics in the paddies and laboratory. The nymphs of BPH had different characters from those of SBPH and WBPH. The nymphs of BPH had white fluorescent spot between bottom of compound eye and antenna, while there was no that spot the other two species. The white spot was the brightest at the nymphs just after hatching and getting weaker as the nymph developed. At last the white spot was totally disappeared at the adult stage. This white spot was innovative criterium to discriminate nymphs of BPH, SBPH, and WBPH in rice paddies.

• Korean journal of applied entomology
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• v.32 no.1
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• pp.68-75
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• 1993

Morphometric investigations of the leg characters of both sexes of brachypterous Korean N. lugens biotypes were made. Simple and multivariate statistical analyses revealed that the three N. lugens biotypes differed from one another. The amount of variation and segregation between and among the three biotype populations were approximated by the scatter plot diagrams based on the computed discriminant scores. The variables of leg characters provided the most significant segregations of three biotype populations, thus, categorizing the three biotypes as distinct intraspecific populations of N. lugens.

• Korean journal of applied entomology
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• v.32 no.2
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• pp.208-217
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• 1993

Feeding behavior fo female brown planthoppers, Nilaparvata lugens Stal, was examined with an electrical recording technique using DC amplifier and through anatomical observation of stylet ovement in the rice plat with electrical recordings. There was six feeding patterns, type P, S, SB, O, X and Ph with the brown planthopper. Type P was a probing pattern during searching the proper feeding site. Type S appeared to be associated with the initial penetration and changing direction through the tissues, and from this type type SB pattern could be distinguished by the regularity of the large potential drops seen, and might be associated with penetration of the phloem sheath and/or salivation in the phloem sheath. The type O pattern shows none of the large voltage drops which were believed to occur when cell walls were being broken down and passes through a relatively thin layer of cells into an air space. The very constant waveform of the type X pattern could be seen during ingestion within the xylem bundle sheath area. The Ph pattern always followed an SB pattern and was associated with a marked negative voltage drop. When this pattern was seen, the brown planthopper might be ingested plant sap from phloem sheath area.

• Korean Journal of Agricultural Science
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• v.49 no.3
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• pp.511-520
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• 2022

Insect-resistant transgenic rice (Bt-T) expresses a toxic protein (mcry1Ac1) derived from the soil bacterium Bacillus thuringiensis found in the rice cultivar Dongjin with an insecticidal property against rice leaf roller (Cnaphalocrocis medinalis). In this study, to investigate the impact of Bt-T on non-target organisms, the feed and oviposition preferences and biological parameters of brown planthopper (Nilaparvata lugens Stål) were comparatively analyzed in four rice cultivars: Dongjin (parent variety), Ilmi (reference cultivar), Chinnong (brown planthopper resistant cultivar) and Bt-T. In the Bt-T and Dongjin cultivars, the feed preferences were 32.4 ± 8.3 and 34.1 ± 6.8%, and the oviposition preferences were 32.5 ± 5.1 and 30.0 ± 5.3% respectively, and there was no statistical significance between these rices. Additionally, in the Bt-T and Dongjin cultivars, the total lifespans from egg to adult were 39.5 ± 6.9 and 40.0 ± 5.8 days, and the weights of adult females were 1.78 ± 0.14 and 1.72 ± 0.16 mg, respectively. Therefore, there was no statistical difference in the biological parameters between these two varieties. Overall, the results indicate that the insect-resistant transgenic rice (Bt-T) did not negatively affect the reproduction and life cycle of brown planthopper, a non-target organism.

• Korean journal of applied entomology
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• v.35 no.1
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• pp.52-57
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• 1996

This experiment was carried out to evaluate the effect of sublethal doses of BPMC, etofenprox,and buprofezin on N. lugens. and its predator C. lividipennis. Buprofezin was found to be the most toxic to N. lugens and the most safe to C. lividipennis among the three insecticides, based on LD50 values. Selective toxicity index calculated by dividing LDSo value of C. lividipennis by that of N. lugens indicated that buprofezin was very safe to C. lividipennis, showing selective toxicity of 2703.3. Longevity and fecundity of N. lugens treated with LDIU and LDm of buprofezin and BPMC were not significantly different with those of untreated brown planthoppers. However, egg hatchability' of N. lugens was greatly reduced when treated with LDm of buprofezin, having the highest inhibition rate of 17.7%. Hatchability of eggs from insects treated with BPMC was similar to that of control. The oviposited peak of treated hoppers appeared late as compared to the untreated which showed the peak at early part of the ovipositional period. The longevity and fecundity of C. lividipennis treated with BPMC were significantly reduced as compared with the untreated. Etofenprox also induced fecundity reduction when treated with LDlo, and LDm. However, C. lividipennis treated with sublethal doses of buprofezin showed no redution in logevity and fecundity. From these results, it may be said that buprofezin can be used to control brown planthopper without disrupting of C. lividipennis population in the rice field.

• Korean journal of applied entomology
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• v.20 no.4 s.49
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• pp.207-211
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• 1981

It has been documented that the resistance to planthoppers is attributed to the feeding preference of the insects. This might be related to difference in the amount of feeding plant sap between resistant and susceptible hosts. In this aspect, this study was conducted to verify it and to develop an effective screening method for resistance to planthoppers by tracer technique. An effective P-32 labelling of rice seedlings at $2\~3$ leaf stage was dipping the roots in concentration of $0.1{\mu}Ci/ml$ solution for 48 hours. Radioactivity was significantly higher in planthopers fed on susceptible variety for 48 hours as compared to those fed on resistant variety. Radioactivity of adults was higher than that of nymphs and also higher in female than male. The results were highly correlated to that indicated by the feeding preference of the insects and therefore, considered to be valid for a screening technique.