Judul: Tingkat infeksi Neozygites fumosa (Speare) Remaudie’re & Keller (Zygomycetes : Entomophthorales) pada kutuputih pe-paya, Paracoccus marginatus Williams & Granara de Willink dan kutuputih singkong, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae) pada tanaman singkong di Wilayah Bogor
Abstrak: Cassava (Manihot esculenta CRANTZ) is one of the most important carbohydrate sources after rice and corn. The papaya mealybug, Paracoccus marginatus and the cassava mealybug, Phenacoccus manihoti have been considered as serious pests on cassava plants. The one of their natural enemy is entomophthoralean fungus. This fungus has been found infect mealybug P. marginatus in Bogor, West Java, Indonesia. However, there is no any report of this fungus infected on P. manihoti in Indonesia. The objective of this research was to explore entomophthoralean fungus on both P. marginatus and P. manihoti. The research was conducted at Sukaraja Kaum Village, and Kebon Awi Village, from March 2012 to June 2012. The mealybugs were sampled from three blocks for each plant. Each block selected 10 plant samples with cross method. The insect populations were counted from 3 parts of leaf (up-center-down). The insect samples were put on 30 ml vials of 70% alcohol. Microscope squash method was made for both mealybugs with a lactophenol-cotton blue. Populations of both species mealybug showed significantly different. Population and infections level on P. marginatus significantly different, while the population of P. manihoti not significantly different and infection levels of fungi significantly different in the two villages observation. Entomophthorales fungi species that infects both mealybug is N. fumosa. Primary conidia, secondary conidia, hyphal bodies, and saprofitic fungi were found infect on both of mealybug.
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Judul: Diversity of Mealybugs (Hemiptera: Pseudococcidae) Associated with Entomophthorales Fungi in Various Plants in Prembun District, Kebumen Regency
Abstrak: Kutu putih merupakan hama polifag yang memiliki kisaran inang yang beragam. Tanaman inang utama kutu putih antara lain singkong, pepaya, terung, dan jambu biji. Pengendalian hayati kutu putih secara alami terjadi karena adanya musuh alami, termasuk cendawan entomophthorales. Cendawan tersebut menjadi salah satu agen hayati yang mampu mengendalikan kelimpahan populasi kutu putih di lapangan. Cendawan entomophthorales merupakan cendawan entomopatogen yang bersifat obligat. Kelimpahan populasi kutu putih memengaruhi tingkat infeksi cendawan entomophthorales. Cendawan entomophthoales Neozygtes fumosa dilaporkan mampu menekan populasi kutu putih Paracoccus marginatus. Identifikasi infeksi cendawan entomophthorales dilakukan pada beberapa spesies kutu putih yang diambil dari berbagai jenis tanaman inang. Fase cendawan yang ditemukan selama penelitan adalah primary conidia, secondary conidia, hypal bodies, resting spore dan cendawan saprofit yang berasosiasi dengan cendawan entomophthorales. Tingkat infeksi pada P. marginatus pada tanaman singkong mencapai 50%., The mealybugs are a polyphagous insects and it has been confirmed that there are many plant families to be hosted. The main host plants of mealybugs were cassava, papaya, eggplant, and guava. One of natural biological controls of mealybugs occur in the field is the entomophthorlean fungus. The objective of this research is to determine several species of mealybugs on several plants and their association with the entomophthoralean fungus. Identification of mealybugs and the infection of entomophthoralean fungus were carried out on several species of mealybugs on various of host plants. The results show that there are several species found at several sampled plants. The phase of the entomophthoralean fungi found were primary conidia, secondary conidia, hyphal bodies, and saprophytic fungi. One species of entomophthoralean fungus, Neozygtes fumosa, was found to be able to suppress the population of papaya mealybugs, Paracoccus marginatus. Infection level of this fungus on Paracoccus marginatus in cassava plants reached at 50%.
Keyword: Infection rate, Neozygites fumosa, Paracoccus marginatus, pest control, population

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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