Judul: Studi Ulat Bulu pada Pertanaman Mangga dengan Perhatian Utama pada Kasus Ledakan di Probolinggo
Abstrak: Selama bulan Maret-April 2011 terjadi ledakan ulat bulu Arctornis submarginata Wlk. (Lep.: Lymantriidae) pada pertanaman mangga di Probolinggo. Pada saat yang bersamaan ledakan ulat bulu dilaporkan pula terjadi di tempat-tempat lainnya. Penelitian bertujuan mempelajari serangan, musuh alami, dan siklus ulat A. submarginata, serta mengidentifikasi jenis-jenis ulat bulu lainnya yang menyerang pohon mangga. Serangan dan musuh alami ulat bulu dipelajari melalui kegiatan survei dan pengumpulan ulat atau kepompong pada pertanaman mangga di Probolinggo, Indramayu, dan Kendal; sedangkan penelitian siklus hidup A. submarginata dilakukan di laboratorium.Hasil survei pada pertengahan Mei 2011 mengungkapan serangan ulatA. submarginata sudah sangat menurun. Menurunnya serangan ulat bulu ini disebabkan oleh meningkatnya perananmusuh alami, yang menyebabkan kematian pada pupa hingga 98%. Musuh alami yang paling umum ditemukan adalah parasitoid Brachymeria sp. dan Xantophimpla sp, serta cendawan entomopatogen yang menginfeksi pupa. Di laboratorium, siklus hidup ulat A. submarginata berlangsung sekitar 47 hari dengan keperidian 200 butir telur.Ulat bulu lainnya dari famili Lymantriidae yang menyerang pohon mangga adalah Lymantria marginata, Orgyia postica, dan Dasychira inclusa.
Keyword: 

Judul: Analisis Hubungan Kondisi Iklim Dengan Ledakan Ulat Bulu: Studi Kasus di Kabupaten Probolinggo, Jawa Timur
Abstrak: An outbreak of caterpillars Arctornis submarginata Wlk.(Lep.: Lymantriidae) occured in nine subdistrict of Probolinggo during March-April 2011. The caterpillar caused heavy defoliation on mangoes, with a total of 14.813 trees affected. Pest populations are commonly strongly influenced by the dynamics of climatic factors. The research aimed to evaluate and analyze the relationship between climatic conditions and the outbreaks of caterpillars. We used a qualitative-descriptive method to analyze rainfall variation for 10 years in the area, regression analysis of climatic factors and pest severity, and climex software to analyze potential pest distribution. Our analysis showed a strong relationship between outbreak of caterpillars and a high rainfall in the study area. The monthly average of rainfall for January to April was higher than monthly rainfall for 10 years. Based on regression analysis, the strongest influence of the whole climatic factors was found on the larval stages of which the value of R2 is 28.9%. Analysis using software climex showed the value of EI (Ecoclimatic Index) is 92, 87 and 46 in compare location, indicating that the study area was more suitable for the caterpillars. Climate is one of the factors affecting caterpillar outbreaks, in addition to biotic factors such as natural enemies.
Keyword: 

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: