Judul: Kelimpahan Artropoda Predator dan Hama pada Tanaman Jambu Biji Kristal di International Cooperation and Development Fund (ICDF) Cikarawang, Bogor.
Abstrak: To apply a wise biological control of pests in an agroecosystem, specific information of abundance and diverstity of natural enemies and pest arthropods are needed. This basic requirement of information, however, in a crystal guava plantation is still neglected. Therefore, the purpose of this research was to explore and identify predators and pest Arthropods associated with crystal guava plantion in International Cooperation and Development Fund (ICDF) Cikarawang, Bogor. These abundance and diversity of arthropods was investigated using pitfall trap, sweep net, light trap, and direct observation methods. Sample plants were selected by forest health monitoring (FHM) cluster design. The result showed that the proportions of pests, predators, parasitoids, and other arthoropods were 53%, 41%, 1% and 5% respectively. The main pests were: Carphopilus sp., rhinoceros beetles, bagworms, budworms, mealy bugs, aphids, and grasshoppers. The most dominant predators were ants (Hymenoptera: Formicidae). Ants were the only predator which found through direct observation methods, pitfall traps, and light traps. Meanwhile Grasshopper (Orthoptera: Acrididae) was the most dominant arthropod catched by insect nets.
Keyword: crystal guava., diversity, predators, forest health monitoring

Judul: Kelimpahan Dan Keanekaragaman Artropoda Predator Serta Artropoda Lainnya Pada Tanaman Jeruk Di Cikarawang, Kabupaten Bogor
Abstrak: Jeruk merupakan salah satu komoditas hortikultura yang paling banyak dikonsumsi di Indonesia. Produksi jeruk mengalami penurunan setiap tahunnya. Hama merupakan salah satu faktor yang menyebabkan penurunan produksi jeruk. Informasi kelimpahan dan keragaman predator dan Artropoda dengan lainnya di perkebunan jeruk adalah persyaratan dasar untuk menerapkan pengendalian hama terpadu (PHT). Penelitian ini bertujuan untuk inventarisasi Artropoda predator dan Artropoda lainnya di perkebunan jeruk Cikarawang, Kabupaten Bogor. Kelimpahan dan keragaman Artropoda diamati menggunakan metode pitfall trap, jaring serangga, light trap, dan pengamatan langsung selama 12 minggu penelitian. Artropoda yang ditemukan dari kelas Arachnida (2 ordo, 18 famili, dan 1 687 spesies), Malacostraca (1 ordo, 1 famili, 12 spesies), Diplopoda (2 ordo, 2 famili, dan 5 spesies) dan Insecta (13 ordo, 102 famili , dan 10 870 spesies). Proporsi herbivor, predator, parasitoid, detrivor, dan lainnya 60%, 25%, 3%, 11%, dan 1%. Predator yang paling banyak ditemukan pada lahan pertanaman jeruk di Cikarawang, Kabupaten Bogor berturut-turut adalah adalah Formicidae, Oxyopidae, Coccinellidae; herbivor adalah Psyllidae, Tetranychidae, Gracillariidae; detrivor adalah Isotomidae, Entomobryiidae, Sminthuridae; dan parasitoid adalah Eulophidae dan Encyrtidae.
Keyword: Arthropoda, jeruk, kelimpahan, keragaman, predator

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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