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: 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: 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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