Judul: Karakteristik Kokon Ngengat Sutera Samia cynthia ricini  (Biosduval) (Lepidoptera: Saturniidae) dengan Pemberian Pakan  Berbeda
Abstrak: Samia cynthia ricini (Lepidoptera: Saturniidae) adalah serangga penghasil sutera yang telah dibudidayakan di berbagai daerah. Ulat sutera S. c. ricini termasuk spesies polifagus yang menggunakan beberapa spesies tanaman sebagai pakan. Penelitian ini bertujuan menentukan durasi tiap fase perkembangan yang dibutuhkan masing-masing fase pradewasa, melakukan karakterisasi kokon dan menguji kualitas serat S. c. ricini dengan pemberian pakan berbeda, yaitu jarak kepyar (Ricinus communis), singkong karet (Manihot glaziovii), dan pepaya jepang (Cnidoscolus aconitifolius). Pemeliharaan larva mulai instar I sampai V. Kokon diamati warna dan diukur bobot, panjang dan diameternya. Kekuatan tarik dari serat tunggal diukur menggunakan alat UTM (Universal Tasting Machine) dan diameter serat diukur menggunakan mikroskop digital Dino-Lite. Daun tanaman pakan larva S. c. ricini dianalisis dengan uji proksimat. Hasil penelitian menunjukkan durasi yang dibutuhkan larva S. c. ricini lebih cepat pada pemberian pakan daun jarak kepyar dibandingkan singkong karet dan pepaya jepang. Karakter kokon S. c. ricini pada pemberian pakan daun jarak kepyar mempunyai bobot dan diameter lebih besar dibandingkan pakan singkong karet. Nilai kekuatan tarik dan regangan serat sutera S. c. ricini lebih tinggi pada pakan daun singkong karet., Samia cynthia ricini (Lepidoptera: Saturniidae) is a silk cocoonproducing insect that has been domesticated in various regions. The silkworm S. c.ricini is a polyphagous species that can use several plant species as food. The purpose of this study were to determine the duration of each pre-adult phase, to characterize of the cocoon, and to measure the tensile of the fibers of S. c. ricini fed by different plants species, namely castor (Ricinus communis), cassava (Manihot glaziovii), and spinach (Cnidoscolus aconitifolius). The larvae (1st -5 th instars) were fed by leaves of each plant. Color of cocoons were observed and weight, length and diameter were measured. The tensile strength of a single fiber was measured using a UTM (Universal Tasting Machine) and the diameter of a single fiber was measured using a Dino-Lite digital microscope. Leaves as feed of S. c. ricini larvae were analyzed by proximate analysis. The results showed that giving of castor leaves result the best growth performance of S. c. ricini larvae and the larvae develope to pupae. The weight and diameter of cocoons fed by castor leaves were greater than that of cassava leaves. The tensile strength and diameter of single fibers of S. c. ricini fed by cassava leave was higher than that of castor.
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Judul: Karakteristik Morfologi Ngengat Sutra Samia cynthia ricini (Lepidoptera : Saturniidae) pada Pemberian Pakan Larva Berbeda
Abstrak: Ngengat Samia cynthia ricini (Lepidoptera: Saturniidae) merupakan serangga penghasil serat sutra komersial yang telah banyak didomestikasi. Kualitas daun pakan mempengaruhi pertumbuhan, mutu kokon dan serat yang dihasilkan. Penelitian ini bertujuan mengkaji karakteristik morfologi S. c. ricini fase larva, pupa, dan imago dengan pemberian tiga pakan larva berbeda. Dalam penelitian ini digunakan tiga jenis pakan larva, yaitu daun singkong karet (Manihot glaziovii), daun jarak kepyar (Ricinus communis), dan daun pepaya jepang (Cnidoscolus aconitifolius). Pengamatan yang meliputi ukuran, bobot, warna dan durasi dilakukan pada setiap fase pertumbuhan. Hasil penelitian menunjukkan pemberian pakan daun jarak kepyar menghasilkan pertumbuhan larva S. c. ricini paling baik berdasarkan karakteristik panjang, lebar dan bobot larva. Terdapat enam variasi warna dan corak larva S. c. ricini yaitu hijau-zebra, hijau, kuning-zebra, kuning, putih-zebra, dan putih. Persentase kokon yang terbentuk paling tinggi terjadi pada pemberian pakan jarak kepyar. Ukuran imago tidak berbeda nyata pada pemberian pakan daun singkong karet dan jarak kepyar. Siklus hidup ngengat S. c. ricini dengan pemberian pakan daun jarak kepyar lebih singkat dua hari dibandingkan dengan pemberian pakan daun singkong karet. Pada pemberian pakan daun pepaya jepang, mortalitas larva instar 5 mencapai 100%., The silkworm Samia cynthia ricini (Lepidoptera: Saturniidae) is a commercial silk fiber-producing insect that has been widely domesticated. Leaf quality as feed will affects growth, cocoon quality, and fiber quality produced of silkworm. This study aims to examine the morphological characteristics of S. c. ricini at the larvae, pupa, and imago phase by three different feeds. In this study, three species of larvae fed were used as feed of larvae, namely cassava leaves (Manihot glaziovii), castor leaves (Ricinus communis), and chaya leaves (Cnidoscolus aconitifolius). Observations including size, weight, color and duration were carried out at each growth phase. The results showed that castor leaves result the best growth of S. c. ricini based on the ratio of length, width, and weight of larvae. There are six variations in color and larvae patterns of S. c. ricini, namely green-zebra, green, yellow-zebra, yellow, white-zebra, and white. The highest percentage of cocoons formed occured in larvae fed by castor leaves. The body size of the imago did not differ on the larvae fed by cassava and castor leaves. The duration of the life cycle of the S. c. ricini larvae fed by castor leaves was two days shorter compared to cassava leaves. Giving of chaya leaves results the mortality of instar 5 larvae reaches 100%.
Keyword: Lepidoptera, life cycle, morphology, Samia cynthia ricini

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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