Judul: Insecticidal activitiy of spiked pepper (Piper aduncum) extracts from riau on the cabbage head caterpillar (Crocidolomia pavonana)
Abstrak: Spiked pepper (Piper aduncum) is a potential source of botanical insecticides. Its insecticidal activity has been widely reported, but the insecticidal activity of this plant collected from different locations has not been much studied, especially in Indonesia. The objectives of this research were (1) to evaluate the toxicity of P. aduncum leaf and fruit extracts from Riau to Crocidolomia pavonana larvae, (2) to evaluate the effect of the four most active P. aduncum extracts on feeding activity of C. pavonana larvae, (3) to evaluate the persistence and phytotoxicity of the four most active P. aduncum extracts, and (4) to examine qualitative property of the test P. aduncum extracts. P. aduncum leaves and fruits collected from ten different locations in Riau were extracted with ethyl acetate using maceration method. The toxicity test was conducted using a residual leaf feeding method. Mortality data was recorded and analyzed using probit analysis. The feeding inhibition activity test of the four most active extract was conducted using a choice method at concentrations of LC25 and LC50. The feeding inhibition data were subjected to analisys of variance followed by Duncan’s multiple range test at 5% level. The persistence of the four most active P. aduncum extracts was tested at LC95 and 2 x LC95 levels using direct spray method on broccoli plants. Mortality data were analyzed by analysis of variance followed by Duncan's multiple test at the 5% level. The symptom of phytotoxicity on broccoli leaves was observed. Qualitative examination of extract components was done using thin layer chromatography technique. Where P. aduncum fruit oil containing 76% dillapiole was included in the TLC test for comparison. The results showed that P. aduncum extracts collected from ten different locations had strong insecticidal activity and are potential to be used as sources of botanical insecticides. Among 20 extracts tested, four extracts had the highest activity, i.e. fruit extract from XIII Koto Kampar (LC95 0.209%), Pekanbaru (LC95 0.211%), Bangkinang Barat A (LC95 0.212%), and Cerenti (LC95 0.216%). The four most active extracts showed antifeedant effect at LC50 level. These four extracts lost their activity after being exposed to sunlight for 24 hours. Plant extracts tested did not cause phytotoxic effect on broccoli. Qualitative examination show the same separation pattern.
Keyword: botanical insecticide, toxicity, persistence, phytotoxicity

Judul: Aktivitas Insektisida Campuran Ekstrak Buah Piper aduncum (Piperaceae) dan Sapindus rarak (Sapindaceae) terhadap Larva Crocidolomia pavonana
Abstrak: Crocidolomia pavonana is an important pest of Brassicaceous vegetable crops. Piper aduncum and Sapindus rarak fruit extracts are potential for the control of C. pavonana larvae. Insecticidal activity of P. aduncum and S. rarak fruit extracts as well as their mixtures was evaluated against C. pavonana larvae in the laboratory. Ethyl acetate P. aduncum (EtPa) extract as well as methanolic S. rarak (MeSr) and aqueous S. rarak (AqSr) extracts were tested separately and in mixtures against second-instar larvae C. pavonana by a leaf-residue feeding method. In general, mortality of C. pavonana larvae in the treatment with all test extracts increased sharply between 24 and 48 hours after treatment (HAT). Based on LC50 and LC95 at 72 HAT, EtPa extract was about 7.7 and 8.1 times and 14.5 and 12.8 times, respectively, more toxic to C. pavonana larvae than MeSr and AqSr extracts. At LC95 level, EtPa + MeSr extract mixture (1:10 w/w) was about 1.64 times more toxic to the test larvae than EtPa + AqSr extract mixture (1:10 w/w). Based on combination index at 48, 72, and 96 HAT assessment, EtPa and MeSr extract mixture at LC50 level as well as EtPa and AqSr extract mixture at LC50 and LC95 levels had additive joint action, while EtPa and MeSr extract mixture at LC95 was weakly synergistic. In addition to lethal effect, the treatment with all test materials delayed the development of C. pavonana larvae from second-instar to fourth instar. Thus, EtPa, MeSr, and AqSr extracts as well as the mixtures between EtPa and S. rarak extracts are potential alternatives for the control of C. pavonana pest.
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Judul: Formulasi Hamilton Untuk Menggambarkan Deformasi Gelombang Soliter Dengan Dasar Tidak Rata Pada Fluida Dua Lapisan
Abstrak: Gelombang internal adalah suatu gelombang yang muncul di bawah permukaan laut sehingga gelombang ini tidak teramati secara kasat mata. Formulasi Hamilton dirumuskan untuk menjelaskan gerak gelombang ini. Dalam hal ini diasumsikan bahwa fluida yang ditinjau terdiri atas dua lapisan dengan masing-masing lapisan memiliki rapat massa yang konstan. Selain itu, diasumsikan pula fluida yang ditinjau berupa fluida tak mampat (incompressible) dan tak kental (invicid). Formulasi Hamilton dilakukan dengan meninjau fluida dua lapisan yang berada pada domain yang dibatasi oleh batas atas yang rata dan batas bawah yang tidak rata. Hamilton (energi total)-nya didefinisikan sebagai penjumlahan antara energi kinetik dan energi potensialnya. Karena energi kinetik tidak secara eksplisit dinyatakan dalam peubah fisis, maka digunakan metode asimtotik untuk menentukan energi totalnya. Dalam hal ini diasumsikan bahwa gelombang interfacial yang ditinjau cukup panjang, dan amplitudo yang cukup kecil. Persamaan Korteweg de- Vries (KdV) diperoleh, jika disumsikan bahwa gelombang interfacial hanya merambat pada satu arah, sedangkan jika gelombang tersebut merambat ke dua arah, diperoleh persamaan Boussinesq.
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