Judul: Deskripsi dan Kunci Identifikasi Parasitoid Nyamuk Ganjur Alang-Alang Orseolia javanica Kieffer & Van Leeuwen-Reijnvaan (Diptera: Cecidomyiidae) di Kabupaten Bogor dan Cianjur
Abstrak: Alang-alang (Imperata cylindrica) adalah salah satu gulma yang sulit dikendalikan di dunia. Nyamuk ganjur alang-alang, Orseolia javanica Kieffer & van Leeuwen Reijnvaan, merupakan serangga yang spesifik menyerang alang-alang dan memiliki tingkat fekunditas cukup tinggi. Potensinya dalam menekan populasi alang-alang masih dihadapkan dengan kendala lain seperti tingginya tingkat parasitisasi di lapangan. Tujuan dari penelitian adalah mendapatkan informasi mengenai parasitoid dan tingkat parasitisasinya pada nyamuk ganjur alang-alang di Kabupaten Bogor dan Cianjur, membuat deskripsi dan kunci identifikasi parasitoid nyamuk ganjur alang-alang, serta mengetahui waktu kemunculan dan nisbah kelamin dari parasitoid nyamuk ganjur alang-alang. Tingkat parasitisasi dari parasitoid nyamuk ganjur alang-alang berkisar 1-20%, meskipun nilainya rendah namun dapat menurunkan populasi nyamuk ganjur alang-alang sehingga menurunkan pula potensinya dalam menekan pertumbuhan alang-alang. Spesies parasitoid yang ditemukan menyerang nyamuk ganjur alang-alang O. javanica dari dua lokasi pengambilan sampel ada delapan spesies parasitoid Hymenoptera dari lima famili antara lain Platygaster orsioliae, Platygaster sp. (Platygastridae), Aprostocetus procerae, Aprostocetus sp. (Eulophidae), Propicroscytus mirificus, Lamprotatus sp. (Pteromalidae), Neanastatus sp. (Eupelmidae), dan Eurytoma sp. (Eurytomidae). Deskripsi dari parasitoid-parasitoid tersebut mencakup sinonim, karakteristik morfologi, kisaran inang, dan lokasi yang ditemukan. Kunci identifikasi dari semua parasitoid yang ditemukan pada penelitian ini berguna untuk memudahkan mengenali spesies parasitoid yang menyerang nyamuk ganjur alang-alang. Berdasarkan hasil pemeliharaan, kisaran waktu kemunculan imago parasitoid dari nyamuk ganjur alang-alang terjadi pada hari ke-2 hingga maksimal hari ke-14 setelah pengambilan sampel. Nisbah kelamin dari sebagian besar parasitoid yang menyerang nyamuk ganjur alang-alang menunjukkan nisbah kelamin bias betina (betina lebih banyak dibandingkan jantan)., Cogongrass (Imperata cylindrica) is one of the most difficult to control weeds globally. The cogongrass gall midge, Orseolia javanica Kieffer & van Leeuwen Reijnvaan, is an insect that specifically attacks cogongrass and has a high level of fecundity. The potential of O. javanica in suppressing the cogongrass population is still faced with other obstacles, such as the high level of parasitization in the field. This study aimed to obtain information about parasitoids and their parasitization level of cogongrass gall midge in Bogor and Cianjur Districts, to create a description and identification key for parasitoids from the cogongrass gall midge, and to determine the time of emergence and sex ratio of the parasitoid from the cogongrass gall midge. The parasitization percentage of the cogongrass gall midge parasitoid ranges from 1-20%. Although the value is low, it can reduce the cogongrass gall midge population and reduce its potential in suppressing cogongrass growth. The parasitoids that were found attacking the cogongrass gall midge O. javanica from the two sampling locations were eight Hymenopteran parasitoid species from five families. They are Platygaster sp., P. orsioliae (Platygastridae), Aprostocetus procerae, Aprostocetus sp. (Eulophidae), Propicroscytus mirificus, Lamprotatus sp. (Pteromalidae), Neanastatus sp. (Eupelmidae), and Eurytoma sp. (Eurytomidae). Descriptions of these parasitoids include synonyms, morphological characteristics, host range, and locations found. The identification key of all the parasitoids found in this study helps make it easier to identify the parasitoid speciesthat attack the cogongrass gall midge. Based on the results of gall maintenance, the average time of emergence of parasitoid imago from the cogongrass gall midge occurred on the 2nd day to a maximum of the 14th
Keyword: alang-alang, keanekaragaman, musuh alami, pengendalian hayati

Judul: Deskripsi dan Kunci Identifikasi Parasitoid Nyamuk Ganjur Alang-Alang Orseolia javanica Kieffer & Van Leeuwen-Reijnvaan (Diptera: Cecidomyiidae) di Kabupaten Bogor dan Cianjur
Abstrak: Alang-alang (Imperata cylindrica) adalah salah satu gulma yang sulit dikendalikan di dunia. Nyamuk ganjur alang-alang, Orseolia javanica Kieffer & van Leeuwen Reijnvaan, merupakan serangga yang spesifik menyerang alang-alang dan memiliki tingkat fekunditas cukup tinggi. Potensinya dalam menekan populasi alang-alang masih dihadapkan dengan kendala lain seperti tingginya tingkat parasitisasi di lapangan. Tujuan dari penelitian adalah mendapatkan informasi mengenai parasitoid dan tingkat parasitisasinya pada nyamuk ganjur alang-alang di Kabupaten Bogor dan Cianjur, membuat deskripsi dan kunci identifikasi parasitoid nyamuk ganjur alang-alang, serta mengetahui waktu kemunculan dan nisbah kelamin dari parasitoid nyamuk ganjur alang-alang. Tingkat parasitisasi dari parasitoid nyamuk ganjur alang-alang berkisar 1-20%, meskipun nilainya rendah namun dapat menurunkan populasi nyamuk ganjur alang-alang sehingga menurunkan pula potensinya dalam menekan pertumbuhan alang-alang. Spesies parasitoid yang ditemukan menyerang nyamuk ganjur alang-alang O. javanica dari dua lokasi pengambilan sampel ada delapan spesies parasitoid Hymenoptera dari lima famili antara lain Platygaster orsioliae, Platygaster sp. (Platygastridae), Aprostocetus procerae, Aprostocetus sp. (Eulophidae), Propicroscytus mirificus, Lamprotatus sp. (Pteromalidae), Neanastatus sp. (Eupelmidae), dan Eurytoma sp. (Eurytomidae). Deskripsi dari parasitoid-parasitoid tersebut mencakup sinonim, karakteristik morfologi, kisaran inang, dan lokasi yang ditemukan. Kunci identifikasi dari semua parasitoid yang ditemukan pada penelitian ini berguna untuk memudahkan mengenali spesies parasitoid yang menyerang nyamuk ganjur alang-alang. Berdasarkan hasil pemeliharaan, kisaran waktu kemunculan imago parasitoid dari nyamuk ganjur alang-alang terjadi pada hari ke-2 hingga maksimal hari ke-14 setelah pengambilan sampel. Nisbah kelamin dari sebagian besar parasitoid yang menyerang nyamuk ganjur alang-alang menunjukkan nisbah kelamin bias betina (betina lebih banyak dibandingkan jantan)., Cogongrass (Imperata cylindrica) is one of the most difficult to control weeds globally. The cogongrass gall midge, Orseolia javanica Kieffer & van Leeuwen Reijnvaan, is an insect that specifically attacks cogongrass and has a high level of fecundity. The potential of O. javanica in suppressing the cogongrass population is still faced with other obstacles, such as the high level of parasitization in the field. This study aimed to obtain information about parasitoids and their parasitization level of cogongrass gall midge in Bogor and Cianjur Districts, to create a description and identification key for parasitoids from the cogongrass gall midge, and to determine the time of emergence and sex ratio of the parasitoid from the cogongrass gall midge. The parasitization percentage of the cogongrass gall midge parasitoid ranges from 1-20%. Although the value is low, it can reduce the cogongrass gall midge population and reduce its potential in suppressing cogongrass growth. The parasitoids that were found attacking the cogongrass gall midge O. javanica from the two sampling locations were eight Hymenopteran parasitoid species from five families. They are Platygaster sp., P. orsioliae (Platygastridae), Aprostocetus procerae, Aprostocetus sp. (Eulophidae), Propicroscytus mirificus, Lamprotatus sp. (Pteromalidae), Neanastatus sp. (Eupelmidae), and Eurytoma sp. (Eurytomidae). Descriptions of these parasitoids include synonyms, morphological characteristics, host range, and locations found. The identification key of all the parasitoids found in this study helps make it easier to identify the parasitoid speciesthat attack the cogongrass gall midge. Based on the results of gall maintenance, the average time of emergence of parasitoid imago from the cogongrass gall midge occurred on the 2nd day to a maximum of the 14th
Keyword: alang-alang, keanekaragaman, musuh alami, pengendalian hayati

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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