Judul: Jenis dan Karakteristik Koloni Kutudaun (Hemiptera: ...Aphididae) pada Gulma di Bogor
Abstrak: Information on the aphids that associated with weeds is relatively limited. The research aimed to study the diversity of aphids and their colony characteristics in weeds at Bogor. The experiments were conducted by doing aphid sampling in 20 locations at Bogor area. Size of colonies, winged aphids (alatae), wingless aphids (aptera), symptomp caused by aphids, and aphids-ants association were observed. Slide preparation of aphids were used to identify the species. The studies have shown that there were nine aphid species found in weeds in Bogor area:, Aphis craccivora Koch, Aphis euginae van der Goot, Aphis gossypii Glover, Aphis spiraecola Patch, Hysteroneura setariae (Thomas), Jaksonia papillata Theobald, Melanaphis sorghi (Theobald), Schizapis graminum (Rondani), and Sitobion miscanthi (Takahashi). H. setariae was found numerously on the weeds. Wingless aphids was found in a big number of population. Weeds belong to the Family Asteraceae were the most attacked by aphids. Fifteen species of ants associated with aphids, they were Acanthomyrmex sp., Acropyga sp., Cardiocondyla sp., Camponotus sp., Cerapachys sp., Crematogaster sp., Dolichoderus sp., Loweriella sp., Monomorium sp., Myrmecina sp., Paratrecina sp., Philidris sp., Polyrhachis sp., Pseudolasius sp., and Tetramorium sp. The pictorial and dichotomy identification keys of aphids were constucted based on the morfological characters.
Keyword: Bogor Agricultural University (IPB), weeds., identification key, colony, aphids, ants

Judul: Jenis dan Karakteristik Koloni Kutudaun (Hemiptera: Aphididae) pada Tanaman Pangan di Bogor dan Cianjur
Abstrak: Kutudaun merupakan hama penting pada tanaman pangan. Kutudaun dapat menyebabkan masalah pada tanaman inangnya, baik secara langsung maupun tidak langsung. Informasi tentang taksonomi, karakter koloni, dan jenis semut yang berasosiasi dengan kutudaun pada tanaman pangan di Bogor dan Cianjur masih sangat terbatas. Penelitian ini bertujuan untuk mengetahui jenis, kisaran inang, karakteristik koloni, dan jenis semut yang berasosiasi dengan koloni kutudaun pada tanaman pangan di Bogor dan Cianjur. Pengamatan dilakukan dengan menghitung jumlah kutudaun yang bersayap dan tidak bersayap, keberadaan semut yang berasosiasi dengan koloni kutudaun, serta mengambil sampel kutudaun dan semut untuk diidentifikasi. Delapan jenis tanaman pangan yang diamati adalah padi, jagung, talas, singkong, kedelai, kacang tanah, ubi jalar, dan gandum. Identifikasi kutudaun dilakukan melalui dua tahap, yaitu membuat preparat slide kutudaun dan identifikasi sampai tingkat spesies dengan menggunakan kunci identifikasi yang telah dipublikasikan. Sembilan spesies kutudaun yang ditemukan pada tanaman pangan adalah Aphis gossypii, A. glycines, A. craccivora, Rhopalosiphum maidis, R. padi, Sitobion avenae, Myzus persicae, Hysteroneura setariae, dan Tetraneura nigriabdominalis. Sebagian besar kutudaun yang ditemukan adalah kutudaun yang tidak bersayap. A. gossypii merupakan spesies kutudaun dengan jumlah paling banyak yang ditemukan pada tanaman pangan. Tanaman yang paling banyak terserang kutudaun adalah famili Poaceae. Koloni kutudaun yang paling sering ditemukan berukuran sedang dengan jumlah 11-50 individu. Jenis semut yang ditemukan berasosiasi dengan koloni kutudaun adalah Nylanderia sp., Polyrhachis dives, Tapinoma sp., Tetramorium sp., Anoplolepis glacilipes, dan Loweriella sp.. Kunci identifikasi bergambar dibuat untuk mengidentifiksi kutudaun pada tanaman pangan di Bogor dan Cianjur.
Keyword: kutudaun, semut, tanaman pangan, identifikasi morfologi

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.
Keyword: