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 Artropoda Predator dan Artropoda lainnya pada Pertanaman Kelapa Sawit (Elaeis guineensis Jacq.) di PTPN VIII Cikasungka, Bogor.
Abstrak: Informasi kelimpahan artropoda predator dan artropoda lainnya pada tanaman kelapa sawit sangat diperlukan dalam pertimbangan pengambilan keputusan pengendalian dengan menggunakan teknik pemanfaatan musuh alami. Tujuan penelitian ini adalah mengeksplorasi dan menginventarisasi artropoda predator dan artropoda lainnya pada tanaman kelapa sawit di PTPN VIII Cikasungka, Bogor. Pengamatan ini dilakukan dengan 3 macam metode yaitu pengamatan langsung digunakan untuk mengamati dan mengambil artropoda yang berada pada tajuk dan disekitar tanaman sampel, pitfall trap digunakan untuk mengambil artropoda yang terdapat pada permukaan tanah, dan jaring serangga digunakan untuk mendapatkan artropoda yang aktif terbang. Hasil penelitian menunjukkan bahwa proporsi peran artropoda sebagai detrivor, predator, hama, dan parasitoid berturut-turut sebesar 71%, 21%, 7%, dan 1%. Artropoda predator yang paling dominan adalah semut (Hymenoptera: Formicidae) sebanyak 493 individu. Artropoda herbivora yang paling dominan adalah belalang (Orthophtera: Acrididae) sebanyak 225 individu. Artropoda detrivor yang paling dominan adalah serangga pengurai tanah (Collembola: Isotomidae) sebanyak 2 175 individu. Artropoda parasitoid yang paling dominan adalah (Hymenoptera: Eulopidae) sebanyak 80 individu.
Keyword: kelapa sawit, musuh alami, parasitoid

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.
Keyword: