Judul: Keanekaragaman Kutu Putih (Hemiptera:  Pseudococcidae) dan Cendawan Entomophthorales pada Berbagai Tanaman di  Kabupaten Bogor
Abstrak: Hama dan penyakit tanaman merupakan salah satu faktor penyebab menurunnya produktivitas tanaman budi daya. Hama kutu putih merupakan serangga yang umum ditemukan pada tanaman budi daya. Serangga ini bersifat polifag yang memiliki inang dari berbagai famili tanaman. Kutu putih umumnya ditemukan secara berkelompok pada bagian tanaman yang terserang dan menghisap cairan tanaman. Cendawan Entomophthorales merupakan salah satu musuh alami kutu putih. Gejala lanjut dari kutu putih yang terinfeksi cendawan Entomophthorales yaitu tubuh kutu putih berwarna abu-abu atau hitam. Tujuan dari penelitian ini adalah untuk mengetahui keanekaragaman kutu putih dan asosiasinya dengan cendawan Entomophthorales pada berbagai tanaman inang. Kutu putih dikoleksi dari tanaman alpukat, biriba, bisbul, jambu kristal, jeruk nipis, nanas, pakcoy, pisang, dan singkong. Kutu putih yang ditemukan sebanyak tujuh spesies, yaitu Dysmicoccus brevipes, Dysmicoccus lepelleyi, Exallomochlus hispidus, Ferrisia virgata, Nipaecoccus sp., Paracoccus marginatus, dan Rastrococcus marginatus. Hanya satu spesies kutu putih yang terinfeksi cendawan Entomophthorales yaitu P. marginatus yang ditemukan pada tanaman pepaya dan singkong. Fase cendawan pada kedua tanaman inang yang ditemukan pada P. marginatus adalah hyphal bodies., Plant pests and diseases are one factor cause decrease in the productivity of cultivated plants. The mealybug pests are common insect pest found on cultivated plants. These insects are polyphagous and have hosts from various plant groups. Mealybugs are generally found in clusters on infested plant parts and suck plant fluids. The entomophthoralean fungus is one of the natural enemies of mealybugs. Mealybugs with gray or black bodies are signs of advanced Entomophthoralean fungal infection. The objective of these research is to determine diversity of mealybugs and it is associated with their entomophthoralean fungus on various cultivated plants. Mealybugs were collected from avocado, biriba, bisbul, crystal guava, lime, pineapple, pakcoy, banana and cassava plants. There are seven species of Mealybugs found during this research: Dysmicoccus brevipes, D. lepelleyi, Exallomochlus hispidus, Ferrisia virgata, Nipaecoccus sp., Paracoccus marginatus, and Rastrococcus spinosus. Only one of mealybugs infected by entomophthoralean fungus is P. marginatus on papaya and cassava plants. Fungal phase on both hosts which found on to be infective P. marginatus is the hyphal body.
Keyword: hyphal bodies, P. marginatus, polyphages

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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