Judul: Keefektifan ekstrak tiga jenis tumbuhan terhadap Paracoccus marginatus dan Tetranychus sp. pada tanaman jarak pagar (Jatropha curcas L.)
Abstrak: Broad-spectrum synthetic pesticides which can cause some undesirable side effects, are commonly used by Jatropha curcas farmer. Thus, safe and effective alternatives need to be developed. The objective of this study was to evaluate the potential of extracts of three plant species, i.e. Piper retrofractum (fruits, direct extraction with ethyl acetate [EtOAc]), Tephrosia vogelii (leaves, direct extraction with EtOAc), and A. indica (seeds, sequential extraction with n-hexane, EtOAc, and methanol), to control Paracoccus marginatus and Tetranychus sp. on J. curcas. Based on LC50 and LC95 values, in general all test extracts were slightly more toxic to P. marginatus and Tetranychus sp. in the tests with residue-on-glass method than with leaf-residue method. In leaf-residue tests, P. retrofractum extract was about 3.3 to 8 times more toxic to P. marginatus (LC50 0.12%) and 1.3 to 21 times more toxic to Tetranychus sp. (LC50 0.22%) than the other test extracts. In residue-on-glass tests, P. retrofractum extract was about 2 to 6.8 times more toxic to P. marginatus (LC50 0.12%) and 6.8 to 11.7 times more toxic to Tetranychus sp. (LC50 0.18%) than the other test extracts. In greenhouse experiments on potted J. curcas, the treatment with P. retrofractum extract reduced the population of P. marginatus by 92.8% compared with control and that of Tetranychus sp. by 98%. This population reduction was better than or comparable with that in the treatment with a synthetic insecticide imidacloprid (78% and 94.7% reduction, respectively). The pest population reduction in the treatment with T. vogelii hexane A. indica extracts was much lower than that in the treatment with imidacloprid.
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Judul: Akivitas insektisida ekstrak piper retrofractum Vahl. dan Tephrosia vogelii Hook. f. terhadap Crocidolomia pavonana (F.) dan Plutella xylostella (L.) serta Keamanan Ekstrak tersebut terhadap Diadegma semiclausum (Hellen)
Abstrak: Piper retrofractum dan Tephrosia vogelii merupakan dua jenis tanaman yang memiliki potensi sebagai insektisida nabati. Meskipun sifat insektisida masingmasing tanaman telah dilaporkan, evaluasi campuran P. retrofractum dan T. vogelii sebagai insektisida nabati masih perlu dilakukan untuk menentukan keefektifannya terhadap ulat kubis Crocidolomia pavonana dan Plutella xylostella serta keamanannya terhadap parasitoid Diadegma semiclausum. Penelitian ini bertujuan menguji (1) efek racun perut dan kontak komponen ekstrak buah P. retrofractum dan daun T. vogelii serta campurannya terhadap larva C. pavonana; (2) efek antifeedant fraksi aktif P. retrofractum dan T. vogelii terhadap larva C. pavonana; (3) efek racun perut fraksi aktif P. retrofractum dan T. vogelii serta campurannya terhadap larva P. xylostella; (4) keamanan fraksi aktif P. retrofractum dan T. vogelii serta campurannya terhadap imago parasitoid D. semiclausum; dan (5) keefektifan fraksi aktif P. retrofractum dan T. vogelii serta campurannya terhadap larva C. pavonana pada tanaman brokoli dalam polybag di lapangan.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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