• Korean journal of applied entomology
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• v.33 no.3
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• pp.173-177
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• 1994

his study was conducted to Investigate the occurrence of small brown planthopper (SBPH), LaodeIpahx striatellus Fallen, and the ind~cence 01 rice virus diseases by d~fferent seeding dates in dryseeded rice. The occurrerlce of SBPH was the highest an nce seeded in May 11, followed byMay 1, May 21 and May 31. However. SBPH dld not occur on the rice seeded in June 10 duelo the rice was emerged after peak occurrence of first generailon adult of SBPH. The occurrenceof the first generation adult of SBPH was May 11 and it was 3-day earlier than that of infantnce transplanting. The ~nd~cencofe rice vlrus diseases, rice stripe vilus (RSV) and rice black-streakeddwarf virus (RBSDV), was the most severe at seeding date May 11. and then followed by May1, May 21 and May 31 Thus the incidence of "ce virus diseases was closely related with thedensity of the first generat~on adult of SBPH Rice yield was decreased by later seeding dates, although rice yield from May 1 to May 21 was relatively stable and hqii compared with laterseeding dates. Accordingly, there was slgniilcant relatlonsh~p between rice yield and seeding datesice yield and seeding dates

• Korean journal of applied entomology
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• v.27 no.2
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• pp.87-93
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• 1988

Some attempts were made to investigate the biological characteristics of the brown planthopper(BPH), Nilaparvata lugens St${\aa}$l, biotypes in terms of perference in feeding oviposition on rice field, egg and nymphal periods, egg hatchability, emergemce ratio, growth index, adult lingevity and gecundity fed on 60-day-old rece cultivaes with different resistance genes. Feeding and oviposition perference of the three BPH biotypes on Dongjinbyeo with no resistance gene were shown very higher than on rice cultivars with resistance genes. Those of biotype-2 on Cheongcheongbyeo with bph 1 gene and bitype-3 on Milyang 63 with bph 2 gene were relatively high, however, they were still remarkably lower than those of Dongjibyeo. The egg and nymphal periods of the three BPH biotyes on Milyang 23 were shorter than on the other rice cultivars. The periods of biotype-2 on Cheongcheongbyeo and biotype-3 on Milyang 63 were as short as those of the three BPH biotypes on Milyang 23. The egg hachability, emergence ratio, and growth index of the three BPH bioyoes on Milyang 23 were higher than on the other rice cultivars and those of biotype-2 on Cheongcheongbyeo and biotyoe-3 on Milyang 63 were as high as on Milyang 23. The female adult longevity of the BPH biotype-1 on Milyang 23 was longer than on the other cultivaes, and that of biotype-2 on Cheongcheongbyeo and bioty-3 an Milyang 63 were as ling as on Milyang 23. The number of egg laid by a female of the three BPH biotypes were greatly increased on Milyang 23. Those of biotype-2 on Cheongcheongbyeo and biotype-3 an Milyang 63 were also greatly increased.