The brown planthopper, Nilaparvata lugens, is a serious pest of rice crops throughout Asia and exhibits wing dimorphism, with brachypterous adults having reduced wings and macropterous adults possessing fully developed wings. To understand the reproductive strategies in two wing-morphs of this insect, the transcript encoding the major yolk protein precursor, vitellogenin (Vg), was cloned. The complete mRNA transcript was 6314 bp, which encodes a protein of 2063 residues including an 18-residue putative signal peptide. Analysis of the mature protein revealed two vitellogenin-N (or lipoprotein amino-terminal) domains near the N-terminus and a von Willebrand factor type D domain near the C-terminus. In addition, a highly conserved motif GL/ICG, and a number of cysteine residues were identified near the C-terminus. Northern blot analysis identified a ∼6.8 kb Vg gene transcript that was expressed exclusively in the adult female fat body cells. The expression profile revealed that the Vg gene starts to be expressed earlier (on day 3) in brachypters as compared to macropters where the mRNA transcript was observed on day 4. However, in both morphs, the amount of Vg mRNA increased to reach high levels during vitellogenic periods [from day 4 (in brachypters) and day 5 (in macropters) and onwards]. Reflecting the RNA transcription pattern, the Vg signal was detected by immunoblotting on day 3 and day 4 in haemolymph of brachypterous and macropterous females, respectively, and that was increased every day and remained high during the vitellogenic periods. Furthermore, the topical application of juvenile hormone (JH) III had up-regulated the Vg gene expression suggesting that the Vg gene is regulated by JH in N. lugens. In addition, it was demonstrated by Southern blot analysis that there exists a single copy of the gene in the N. lugens genome. A delayed trend in expression (of both the transcript and the protein) demonstrated by macropterous females in the present studies supports the hypothesis of prereproductive long distance migration in this wing-dimorphic species.

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Biotypes cause a serious problem in controlling brown planthopper (BPH), Nilaparvata lugens Stål (Homoptera: Delphacidae). We characterized four BPH strains, which were collected in different localities in Japan and maintained by random mating within each strain for different periods. The virulence of the BPH strains was evaluated based on their postembryonic development on susceptible and resistant rice lines and inhibition of rice seedling growth. Two single resistance gene introgression lines, "Norin-PL3 (Bph1 carrier)" and "Norin-PL4" (bph2 carrier), and a pyramided line in which both genes were combined were used with a susceptible japonica recurrent parent "Tsukushibare" as a control. Sequence comparison of the mitochondrial cytochrome oxidase-I (COXI) gene was also performed in the characterization. The four BPH strains were classified into two or three groups with unique virulence spectra. The oldest strain showed avirulence against both introgressed resistance genes, while the three younger strains showed strong virulence against one or both genes. The different virulence spectra suggested the sequential adaptation of these BPH strains to the two resistance genes. Pyramiding of the resistance genes had no additive effect on rice seedlings carrying them even against avirulent and less-virulent BPH strains.

The study aimed at examining the effect of reciprocal teaching strategy on students’ academic achievement in the subject of general science at elementary level. The objectives of the study were; (i) to investigate the effect of using reciprocal teaching strategy on academic achievement of 5th grade students, (ii) To investigate the effect of reciprocal teaching strategy on high achiever and low achiever of 5th grade, (iii) To observe the participation of the students in reciprocal teaching strategy. Sample of the study was consisting of 40 students studying general science in class 5th. A Pre-test Post- test equivalent group design was used to conduct the study. For collection of data teachers made test and observation sheets were developed. Statistical techniques such t-test, percentage, S.D and mean were used to analyze the collected data. The study is equally significant for students, teachers, curriculum developers and future researchers. It was found that the participation of students was significant in reciprocal teaching strategy during treatment. The participation of students in reciprocal teaching strategy reported an increasing trend after the first week to week 6.With the help of reciprocal teaching strategy students readiness to learn, their attention to reading and listening, their ability to generate questions from the text, their activeness during the discussion and their confidence about sharing their ideas in a group increased hundred percent. Reciprocal teaching had great effect on student’s academic achievement.