Judul: Diversity of Ants Species on Pineapple (Ananas comosus (L.) Merr.) Plantations  in Central Lampung District
Abstrak: Nanas salah satu komoditas sumber devisa negara Indonesia dari sektor pertanian. Serangan patogen PMWaV dapat menurunkan produktivitas pertanaman nanas. Vektor penyakit ini adalah kutu putih yang bersimbiosis dengan semut sehingga menyebabkan penyebaran penyakit semakin luas. Penelitian ini bertujuan mengetahui keanekaragaman spesies semut dan peranan semut di perkebunan nanas. Pengambilan sampel semut dilakukan di perusahaan swasta Kabupaten Lampung Tengah pada lima petak (H1, H2, G1, G2, dan M1). Sampel semut diidentifikasi berdasarkan karakteristik morfologinya, kemudian dihitung tingkat keanekaragamannya menggunakan Indeks Shannon-Wiener (H'), Evennes (E), dan Simpson (D). Hasil analisis data semut di perkebunan nanas Kabupaten Lampung Tengah masing-masing indeks secara berurutan menunjukkan kategori sedang (1 < H' < 3), tinggi (E > 0,6), dan rendah (0 < D < 0,5). Spesies semut yang ditemukan pada perkebunan nanas Kabupaten Lampung Tengah yaitu subfamili Formicinae (Polyrhachis sp., Nylanderia sp., Camponotus sp., Anoplolepis gracilipes), subfamili Myrmicinae (Monomorium pharaonis, Pheidole sp., Solenopsis geminata), subfamili Dolichoderinae (Tapinoma melanocephalum, Technomyrmex sp.), dan subfamili Ponerinae (Odontomachus sp., Odontoponera sp.). Spesies Nylanderia sp., S. geminata, dan T. melanocephalum dominan berinteraksi dengan kutu putih Dysmicoccus brevipes dan Dysmicoccus neobrevipes. Implikasi dari penelitian ini dapat diketahui spesies semut yang berinteraksi dengan kutu putih, sehingga diharapkan dapat ditekan distribusinya.
Keyword: ant, PMWaV, morphological characteristics

Judul: Species Diversity of mealybugs on Pineapple Plants (Ananas comosus (L.)) In Central Lampung and Blitar Regency
Abstrak: Kutu putih dapat ditemukan hampir di seluruh pertanaman nanas. Serangga ini merupakan hama utama tanaman nanas. Serangan kutu putih pada tanaman nanas ditandai dengan munculnya material berwarna putih pada daun yang mengganggu proses fotosintesis tanaman. Berbagai penelitian mengenai identifikasi kutu putih sudah banyak dilakukan, namun pembuatan kunci identifikasi kutu putih pada pertanaman nanas belum pernah dilakukan. Sehingga, penelitian mengenai Inventarisasi dan Kunci Identifikasi Kutu Putih pada pertanaman nanas perlu dilakukan. Tujuan penelitian untuk mengidentifikasi berbagai spesies kutu putih, mengetahui karakterisitik khusus setiap spesies, serta penyusunan kunci identifikasi kutu putih di perkebunan nanas di Blitar dan Lampung. Penelitian dilaksanakan dalam empat tahap, yaitu pengamatan lapangan, pengumpulan data primer, identifikasi dan pembuatan kunci identifikasi. Pengamatan lapang dilakukan pada perkebunan nanas milik perseorangan di Kecamatan Gandusari, Kabupaten Blitar dan Kecamatan Terbanggi Besat, Kabupaten Lampung Tengah dengan metode observasi langsung dengan mengamati 105 sampel kutu putih yang ditemukan pada pertanaman nanas di setiap tempat pengamatan dilakukan. Pengambilan data menggunakan metode pengambilan sampel acak dari setiap area. Kemudian kutu putih dipreparasi dan diidentifikasi dengan bantuan mikroskop. Berdasarkan hasil identifikasi ditemukan kutu putih yang berasal dari tiga genus berbeda yakni Ferrisia, Dysmicoccus dan Planococcus. Hasil identifikasi dibuat tabel matriks karakteristik tiap spesies untuk pembuatan kunci identifikasi., Mealybugs can be found almost throughout the pineapple plantation in the world. This insect is the major pest of pineapple. Mealybug's attacks on pineapple plants are characterized by the appearance of white material on the leaves that interferes with the plant's photosynthesis process. Various studies on the identification of mealybugs have been carried out, but the key to identifying mealybugs in pineapple plantations has never been done. Thus, research on inventory and key identification of mealybugs in pineapple plants must be made. The purpose of the study was to identify various species of mealybugs, determine the specific characteristics of each species, as well as the preparation of identification keys for mealybugs in pineapple plantations in Blitar and Lampung. The research was conducted in four stages: field observation, primary data collection, identification, and identification of key production. Field observations were carried out on individually owned pineapple plantations in Gandusari District, Blitar Regency, and Terbanggi Besar District, Central Lampung Regency, with direct observation method by observing 105 samples of mealybugs found on pineapple plantations in each place where observations were made. Data is collected using a random sampling method from each area. Then the Mealybugs are prepared and identified using a microscope. Based on the identification of mealybugs, there are three different genera: Ferrisia, Dysmicoccus, and Planococcus. The identification results are made into a Matrix Table of characteristics of each species for the manufacture of identification keys.
Keyword: Karakteristik, Kunci identifikasi, Kutu putih

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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