Judul: Insecticidal activity of sugar-apple (Annona squamosa L.) seed extracts from different locations and synergism of the most active extract with spiked-pepper (Piper aduncum L.) fruit extract against Crocidolomia pavonana (F.) (Lepidoptera: Crambidae) larvae
Abstrak: Results of leaf-residue bioassays of methanolic sugar-apple (Annona squamosa L.) seed extracts from eight locations in Central Java and Papua showed that LC50 of the extracts against Crocidolomia pavonana larvae ranged from 27.6 to 374 ppm, whereas the range of LC95 was 160.8-6067.8 ppm. Sugarapple extract from Sumber Lawang-Blora, Central Java had the lowest LC50 value, while the extract from Cepu-Blora had the lowest LC95. The difference in the slope of probit regression of sugar-apple extracts resulted in the difference in LC95/LC50 ratio. Spiked-pepper (Piper aduncum L.) fruit extract (LC50 867 ppm and LC95 3122.7 ppm) was much less active than the most active sugar-apple extract. The mixture of sugar-apple seed extract and spiked-pepper fruit extract (1:10) (LC50 66.3 ppm and LC95 1686.9 ppm) had strongly synergistic joint action at LC50 level (combination index 0.30) but antagonistic at LC95 level (combination index 1.59). In a semifield experiment, addition of spiked-pepper extract, neem (Azadirachta indica) seed extract or an optical brightener did not significantly increase the effectiveness of sugar apple seed extract against C. pavonana larvae on polybagged chinese cabbage plants.
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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: igenvalues and Eigenvectors of Tridiagonal Matrix with Non Constant and Recurrent Diagonal Entries.
Abstrak: Matriks tridiagonal adalah suatu matriks yang mempunyai entri-entri bernilai nol kecuali pada diagonal utama, di bawah diagonal utama (subdiagonal) dan di atas diagonal utama (superdiagonal). Entri pada diagonal utama tidak konstan dan berulang. Setiap entri pada matriks tridiagonal ini adalah bilangan kompleks. Dalam karya ilmiah ini, akan dibuktikan 3 teorema untuk menentukan nilai eigen dengan 2 kasus dan 1 teorema untuk menentukan vektor eigen. Teorema pertama menentukan polinomial karakteristik dari matriks tridiagonal. Polinomial karakteristik dari matriks tridiagonal tersebut digunakan untuk menentukan nilai eigen pada teorema kedua dan ketiga serta menentukan vektor eigen pada teorema keempat
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