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: Distribution of Mealybugs (Hemiptera: Pseudococcidae) and Entomophthoralean Fungus on Various Plants at Banyumas Regency
Abstrak: Beberapa kutu putih merupakan spesies hama yang termasuk serangga yang mudah menyebar dengan cepat dan memiliki banyak tanaman inang. Ada beberapa kendala ketika upaya pengendalian kutu putih dilakukan. Tubuh kutu putih ditutupi dengan lapisan lilin yang bersifat hidrofobik, sehingga serangga ini sulit dikendalikan dengan pengendalian kimiawi. Penelitian ini bertujuan untuk mengidentifikasi spesies kutu putih pada beberapa tanaman, dan mengetahui asosiasinya dengan Cendawan Entomophthorales. Penelitian dilakukan di tiga kecamatan di Kabupaten Banyumas. Setiap spesies kutu putih pada setiap tanaman diambil sampelnya. Serangga sampel dimasukkan ke dalam botol berisi alkohol 70% untuk selanjutnya dilakukan pemeriksaan laboratorium. Serangga sampel dikumpulkan dengan menggunakan metode purposive random sampling. Data ditabulasi dengan Microsoft Excel 2013 dan SAS 9.0.2. Terdapat 8 spesies kutu putih yang ditemukan pada berbagai tanaman di Kabupaten Banyumas. Infeksi cendawan Entomophthorales terjadi pada Ferrisia dasyrilii, dan Pseudococcus jackbeardsleyi. Kutu putih Paracoccus marginatus merupakan spesies yang paling banyak ditemukan pada tanaman singkong di Kabupaten Banyumas. Infeksi cendawan Entomophthorales pada tanaman singkong terjadi pada Ferrisia virgata di Kecamatan Cilongok, dan pada spesies P. marginatus di Kecamatan Rawalo., Some mealybugs are pest species including insects that spread quickly and have many host plants. There are several obstacles when efforts to control mealybugs are carried out. The mealybugs body is covered with a layer of wax. This wax is hydrophobic, making the insect difficult to be controlled by chemical spraying. The study aimed to identify mealybugs species on several plants, and determine its association with entomophthoralean fungus. The research was carried out at three districts at Banyumas Regency. Each species of mealybugs on each plant was sampled. Sampled insects were put in vial containing 70% alcohol for the next laboratory’s examination. Sampled insects were collected using purposive random sampling method. Data were tabulated by Microsoft Excel 2013 and SAS 9.0.2. There were 8 species of mealybugs found on various plants at Banyumas Regency. Infection of Entomophthoralean fungus occurred on Ferrisia dasyrilii, Paracoccus marginatus, Planococcus minor, Pseudococcus cryptus, and Pseudococcus jackbeardsleyi. Species P. marginatus was the most species found on cassava plants at Banyumas Regency. The infection of Entomophthoralean fungus on cassava plant occurred on Ferrisia virgata at Cilongok District, and on P. marginatus at Rawalo District.
Keyword: Pseudococcidae, pest control, infection rate

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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