• 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.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.

• Korean journal of applied entomology
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• v.27 no.2
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• pp.63-67
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• 1988

Biotypes of the brown planthopper(BPH), Nilaparvata lugens St l, population migrated from maninand China in to southern coastal regions of Korea were investigated in 1985-1987 by honeydew excretion test using Korean cultvars,, 'Milyang 23'(no resistant gene), 'Cheongcheo-ngboy'(bph 1 gene), 'Milyang 63'(bph 2 gene) and 'Gayabyeo'(bph 1 and bph 2 gene). There was a correlation between the amount of honeydew excreted and the ability of each biotype to infest resistant cultivars: 'Milyang 23' with no resistant gene was highiy susceptible to bioty-pe-1, 2 and 3 ; 'cheongcheongbyeo' with resistant bph 1 was susceptible to biotype-2: and 'Milyang 63' with resistant bph 2 gene was highiy resistant to biotype-1, 2 and 3. Percent biotype dis-tribution of the female BPH collected in the southern coastal regions of Korea showed that in 1985, 1986 and 1987, the BPH biotype-1 was predominant accounting for 64.7%, 61.2% and 57.9%, respectivley, whereas bitype-2 was 22.0%, 21.9% and 29.7%, and biotype-3 was 13.3%, 17.0% and 12.6%, repestively.

• Korean journal of applied entomology
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• v.20 no.1 s.46
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• pp.15-20
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• 1981

To analyze the inheritance of emergence rate of brown plant hopper (Nilaparvata lugens) biotypes, six crosses among biotype 1, biotype 2 induced by rearing on Mudgo and biotype 3 these on ASD 7, were made. Each generation $(P_1,\;P_2,\;F_l\; F_2,\;BC_1,\;BC_2)$ of each cross was fed on the rice seedlings of Mudgo and ASD 7 varieties. The emergence rate of biotpe 2 on Mudgo was controlled by the one incomplete dominant gene in $biotype\;l{\times}biotype$ 2 coross, however, that of biotype 3 on ASD 7 was controlled by one incomplete recessive gene in $biotype\;l{\times}biotype$ 3 cross. The genes involved in biotype 2 and biotype 3 were not identical, however, their allelic relations are not clear.

• The Korean Journal of Pesticide Science
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• v.9 no.1
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• pp.88-96
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• 2005

Paraquat-resistant biotype of Conyza canadensis (L.) Cronq. was determined by chlorophyll loss and random amplified polymorphic DNA (RAPD) analysis and the resistant mechanism was investigated with respect to absorption, translocation, and binding constant. RAPD analysis for paraquat resistant (R) and susceptible (S) biotypes found in a pear orchard revealed that the biotypes possessed remote genetic relationship. Chlorophyll loss, as an indication of paraquat toxicity, of S biotype was 7.8-fold greater than that of R biotype. There were no differences in contents of epicuticular wax and cuticle and amounts of [14C]paraquat penetrating the cuticle between the two biotypes. Little translocation of the herbicide out of the treated leaf was observed in either biotype. Binding constants of paraquat to the cell wall and thylakoid membrane were 7.4-fold and 16.9-fold, respectively, higher in R biotype than in S biotype. The results suggest that the resistance mechanism of C. canadensis biotype is due partly to high binding affinity of paraquat to the cell wall and thylakoid membrane.

• Korean Journal of Weed Science
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• v.10 no.4
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• pp.338-343
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• 1990

The intraspecific susceptibility of twelve Echinochloa colona(L.) Link ecotypes to herbicides was studied at three different stages of growth. At germination and post-germination stage, the Batangas ecotype was most susceptible to both butachlor (N-butoxymethyl-2-chloro-2', 6'-diethylacetanilide) and thiobencarb (S-4-dichlorobenzyldiethylthiocarbamate), whereas the Bukidnon ecotype was the most tolerant. The susceptibility of the ecotypes used was not associated with the seed weight and maturity. When the preemergence herbicides were applied at the 2-leaf stage of the ecotypes, the Nueva Ecija ecotype was least susceptible to butachlor at 1 ppm, but it was most susceptible to thiobencarb. The reverse was exhibited by the Cagayan ecotype. Differential susceptibility of the ecotypes to propanil (3', 4'-dichloropropionanilide) as determined by the necrotic length of the third leaf of 20-day-old seedlings was pronounced in the Camarines Sur, Iloilo, and IRRI (red) ecotypes. However, no necrotic tip appeared in the Cagayan and Batangas ecotypes. The differential responses varied with the type and the concentration of the herbicide studied and the growth stage of the ecotypes.

• Korean journal of applied entomology
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• v.32 no.3
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• pp.317-322
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• 1993

Morphological investigations of the abdominal lateral lobes in females and the unguitractor p plates in the tarsi of legs in male and female N. lugens among the three Korean N. lugeηs bio-types revealed that the three biotypes varied from one another. The presence of a distinct ‘cut’ on the lateral lobes in brachypterous females distinguished Biotype 2 from Biotypes 1 and 3. The highest frequency of inserted unguitractor plates in fore-and mid-tarsal segments was exhibited by Biotype 2 in both sexes of each morphs.

• Korean Journal of Environmental Biology
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• v.33 no.4
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• pp.403-411
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• 2015

To understand differences of environmental factors and planktonic communities in closed (CS) versus open (OS) enclosed experimental systems, we performed a study on a 100-L indoor-type artificial marine microcosm. For environmental factors, including water temperature, dissolved inorganic phosphorus, and dissolved silica, there were no significant differences between CS and OS; however, salinity was higher in CS than that of OS due to the evaporation effect. The concentration of dissolved oxygen and dissolved inorganic nitrogen was lower in CS than in OS. The abundance of phytoplankton was lower in CS than in OS. However, abundance of autotrophic nanoflagellates and heterotrophic bacteria varied inversely with that of phytoplankton abundances. In particular, the abundance of heterotrophic nanoflagellates and ciliates increased with bacterial growth after a time lag. Therefore, environmental factors and planktonic communities in CS gradually changed over time and characterized a different artificial ecosystem than in OS.

• Korean journal of applied entomology
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• v.53 no.4
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• pp.465-472
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• 2014

The tobacco whitefly, Bemisia tabaci, infest the Oriental melon and give significant economic damage along with its virus-vectoring activity. Various biotypes of B. tabaci have been well known and are classified depending on the severity of crop damage and insecticide susceptibility. In this study, B. tabaci adults were collected in the melon fields located in Poongchun-myeon, Andong, Korea and diagnosed on their biotypes using PCR molecular markers. From the all the 11 greenhouses, B. tabaci biotype Q was identified. In addition, biotype B adults were also found from the 4 greenhouses. These results report the first occurrence of B. tabaci at the Oriental melon farms in Gyeongbuk province with mixed infection by the two biotypes in the area.

• Korean journal of applied entomology
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• v.24 no.4 s.65
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• pp.209-218
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• 1986

This study was performed to evaluate the differences in resistance of rice varieties to biotypes of the brown planthopper (BPH), capable of surving on the Milyang 30 and Milyang 63 varieties which have Bph 1 and bph 2 gene for resistance, respectively. The rice varieties tested were Milyang 30, Cheongcheong, Milyang 63 and Gaya which have been reported as having resistant genes for the BPH. The check varieties were Chucheong and Sangpoong which have no resistant gene. The degree of resistance to the BPH biotypes indicated that Milyang 30, Cheongcheong, Milyang 63 and Gaya varieties were highly resistant to the biotype 1. But their reactions against biotype 2 and 3 were variable, namely Milyang 30 and Cheongcheong were susceptible to biotype 2, and Milyang 63 was susceptible to biotype 3. In the esterase isozyme patterns of brown rice the bands of ${\beta}-1,\;{\beta}-3\;and\;{\beta}-5$ were detected in Chucheong and Sangpoong, while the bands of ${\alpha}-1,\;{\beta}-2\;and\;{\beta}-5$ were detected in the test varieties which have genes for resistance. However, the bands of ${\beta}-5$ in Milyang 63 and Gaya were stronger than those of Milyang 30 and Cheongcheong varieties. In the root of 10-days seedling, the esterase bands of ${\alpha}-2,\;{\beta}-2\;{\beta}-4\;and\;{\beta}-5$ were detected in Chucheong and Sangpoong, while the bands of ${\alpha}-1,\;{\beta}-1\;{\beta}-3\;and\;{\beta}-5$ were detected in the tested different varieties. But the bands of ${\alpha}-1\;and\;{\beta}-5$ in Milyang 63 and Gaya were stronger than those of Milyang 30 and Cheongcheong varieties.