Judul: Kajian Resistensi Lima Varietas Sorgum terhadap Rhyzopertha dominica (F.) (Coeloptera: Bostrichidae).
Abstrak: Sorghum is a cereal crop source of carbohydrate that can be used as a substitute for rice. Sorghum seed storage facing many problems caused by stored product pest, one of them is Rhyzopertha dominica (F.). Damage to sorghum seed caused by insect pests reach 30%. The objective of this research was to evaluate the resistance of five sorghum varieties against R. dominica during storage. Research was conducted at Entomology Laboratory SEAMEO- BIOTROP. Bioassays were conducted by infesting 40 adults of R. dominica to 1000 ml plastic jar containing 100 g sorghum seed for 14 days and then taken out from the jars. All the jars, then incubated for 42 days. Five sorghum varieties tested were Numbu, local Bandung , Local Wonogiri, CTY-33, and B-76. Between day 42-80, all F1 adults came out from the seeds were counted. Resistance level then determined by Dobie Index of Susceptibility (DIS). Weight loss from each variety were also calculated. Research result showed that CTY-33 was the most resistant variety with DIS value of 3.814, seed hardness seemed to be the resistance factor.
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Judul: Kajian Pola Pertumbuhan Populasi Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) pada Lima Varietas Sorgum
Abstrak: Sorgum merupakan tanaman serealia yang dapat digunakan sebagai pangan, pakan ternak, dan bioetanol (bioenergi). Penanganan pascapanen yang kurang baik dan lama penyimpanan dapat memengaruhi keutuhan butir sorgum serta ketahanannya terhadap serangga hama salah satunya Rhyzoperta dominica. Susut bobot yang disebabkan aktifitas hama ini mencapai 30% selama 3 bulan penyimpanan pada suhu kamar. Penelitian ini bertujuan untuk mengetahui pola pertumbuhan populasi R. dominica dan susut bobot pada 5 varietas sorgum dengan kadar air awal serta populasi awal yang berbeda. Serangga uji adalah imago berumur 0 sampai 14 hari. Wadah plastik berisi 250 g biji sorgum lima varietas ditetapkan kadar air yaitu 12, 14, 16, dan 18% yang diinfestasikan dengan tingkat populasi awal 0, 10, 20, dan 30 serangga uji. Setelah inkubasi 60 hari, semua unit percobaan dibongkar dan dilakukan penghitungan jumlah imago F1 dan susut bobot dihitung berdasarkan metode Adams. Terdapat korelasi positif yang signifikan antara populasi awal dengan populasi akhir, populasi awal dengan susut bobot, dan populasi akhir dengan nilai susut bobot. Analisis regresi menunjukan bahwa pola pertumbuhan R. dominica berbeda antar varietas.
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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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