Effects Of Different Environmental Condition On Wing Dimorphism Of Brown Planthopper And Construction A Normalized Full-length CDNA Library Of Macropterous Adults

The brown planthopper (Nilaparvata lugens Stal.L) is Delphacidae Homoptera and one of the major pests of rice in Asia. Here we identified the biotype of the brown planthopper in ShiZiShan WuChang with Standard Seedbox Screening Technique(SSST), and researched on the wing dimorphism affected by the illumination, nymphal density, fertilization, irrigation and rice variety in and out of the laboratory, in order to control BPH effectively. Meanwhile, we constructed a normalized full-length cDNA library of macropterous adults, to provide basic for expounding the molecular mechanism of wing dimorphism. The main results in this study are showed as follows:1. In SSST identification of the biotype, BPH in ShiZiShan WuChang was resistant to TN1, IR₂₆ and ASD₇, but susceptive to RH and Ptb33. According to the standard in IRRI, the dominant population of BPH had been converted from biotype II to biotype Bangladesh, which was more harmful.2. The effects of illumination and nymphal density on wing dimorphism in room were studied, the results showed that at the condition of short illumination and nymphal density under 20 per plant, the percentage of brachypterous female was over 87.22%, the condition was applicable for the formation of brachypterous female. At the condition of long illumination and the nymphal density over 10 per plant, the percentage of brachypterous female was below 46.67%, and this condition was applicable for the formation of macropters female.These results indicated that nymphal density and illumination could influence the wing dimorphism of BPH Bangladesh, with the increase of nymphal density, the percentage of brachypterous female decreased, the short illumination was benefited for the formation of brachypterous.3. The effects of fertilization on wing dimorphism in outer room were studied, the results showed that the percentage of brachypterous female was highest among differert disposal, when the concentration of fertilizer was 75kg/hm², but the percentage of brachypterous female declined, when the concentration of fertilizer was 150kg/hm².4. The effects of different rice varieties on wing dimorphism in outer room were studied, the results showed that the percentage of brachypterous male was low on tested rice varieties, but the percentage of brachypterous female was over 73% on the sensitive rice liangyoupeijiu and TN1, the percentage of brachypterous female was different with different rice varieties. Sensitive rice was benefit for the formation of brachypterous female.5. The percentage of brachypterous male individual was low under different conditons. Only with 75kg/hm² fertilizer in outer room, the percentage of brachypterous female was reached 71.82%, this indicated that different environment conditons have a stronger abduction for wing dimorphism of female individual than male.6. A normalized full-length cDNA library from BPH was constructed in this study. The "anchor first-strand cDNA" containing a symmetrical sfiI restriction enzyme sites (A&B) was synthesized by total RNA with the Creator SMART technique. Double strand cDNA was normalized through Duplex-Specific Nuclease (DSN). The containing capacity of the cDNA library was 4.48×10⁵, with a recombinant rate of 93.33%. 192 clones random selected were sequenced and 161 high quality ESTs were obtained. They were composed of 5 contigs and 151 singlets, the rate of redundancy was only 3.56%, and the percent of full-length cDNA was 55.13%. These results indicated that a high quality library was met the follow analysis, it can provide basic for expounding the molecular mechanism of wing dimorphism.