Judul: Infestation Level of the Yellow Rice Stem Borer, (Scirpophaga incertulas) and its Parasitizing Level of Egg Parasitoid in Pacet  Subdistrict, Bandung Regency
Abstrak: Produksi padi di Indonesia setiap tahun mengalami penurunan yang salah satunya diakibatkan oleh organisme pengganggu tanaman (OPT). Penggerek batang padi merupakan salah satu OPT yang seringkali menyebabkan penurunan hasil terutama di Provinsi Jawa Barat. Aplikasi insektisida merupakan salah satu upaya yang seringkali dilakukan oleh petani. Akan tetapi, penggunaan insektisida secara berlebihan dapat menimbulkan berbagai efek negatif baik terhadap lingkungan maupun konsumen. Oleh karena itu, diperlukan penerapan konsep pengendalian hama secara terpadu (PHT). Salah satu upaya tersebut adalah dengan pemanfaatan musuh alami, yaitu parasitoid telur. Keberadaan hama maupun musuh alami sangat terpengaruh oleh lingkungan salah satunya ketinggian. Oleh karena itu penelitian dilaksanakan dengan tujuan memperoleh informasi mengenai intensitas serangan dan penyebaran populasi masing-masing parasitoid telur pada ketinggian 800 m dpl dan >1000 m dpl. Pengamatan dilakukan di Desa Pangauban dengan ketinggian 1087 m dpl dan Desa Tanjungwangi dengan ketinggian 866 m dpl, yang terletak di Kecamatan Pacet, Kabupaten Bandung. Ditentukan lahan pengamatan dari masing-masing lokasi, terdiri atas lahan pengambilan sampel kelompok telur dan lahan pengamatan kerusakan tanaman oleh penggerek batang padi kuning (PBPK). Setiap lokasi pengamatan ditentukan 5 petak yang memiliki ukuran 5 m 5 m dengan metode diagonal satu arah. Pengamatan dilakukan secara langsung dengan menghitung intensitas serangan pada 10 rumpun di masing-masing petak sebanyak 4 kali masa pengamatan. Kemudian dilakukan pengambilan kelompok telur setiap 2 minggu sekalisebanyak 4 kali pada lahan seluas 2 ha yang dibagi menjadi 4 bagian. Hasil penelitian ini menunjukkan bahwa faktor lingkungan serta cara budi daya dapat memengaruhi intensitas serangan penggerek pada pengamatan 4 dan 6 minggu setelah tanam (MST). Faktor lingkungan juga memengaruhi spesies parasitoid yang ditemukan selama penelitian., Rice production in Indonesia has decreased every year, one of which is due to the presence of plant pest organisms (PPO). Rice stem borer is one of the pests that often causes a decrease in yield, especially in West Java Province. The application of insecticides is one of the efforts that are often carried out by farmers. However, excessive use of insecticides can cause various negative effects on both the environment and consumers. Therefore, it is necessary to apply the concept of integrated pest management (IPM). One of these efforts is the use of natural enemies, namely egg parasitoids. The presence of pests and natural enemies is greatly affected by the environment, one of which is altitude. Therefore, the research was carried out to obtain information about the intensity of attack and population distribution of each egg parasitoid at an altitude of 800 m asl and > 1000 m asl. Observations were made in Pangauban Village with an altitude of 1087 m asl and Tanjungwangi Village with an altitude of 866 m asl, which are located in Pacet District, Bandung Regency. The observation area was determined from each location, consisting of an egg group sampling area and observation area for plant damage by the yellow rice stem borer (YRSB). Each observation location was determined by 5 plots with a size of 5 m × 5 m using the one-way diagonal method. Observations were made directly by calculating the intensity of the attack on 10 clumps in each
Keyword: altitude, infestation levels, egg parasitoids, paddy

Judul: Parasitization Levels and Species of Egg Parasitoid on Yellow Rice Stem Borer (Scirpophaga incertulas) at Paddy Field, Karawang District
Abstrak: Produksi padi di Indonesia masih mengalami penurunan signifikan yang disebabkan oleh organisme pengganggu tanaman (OPT), salah satunya adalah penggerek batang padi kuning (PBPK), Scirpophaga incertulas. Pengendalian hama tersebut yang umum dilakukan oleh petani adalah penggunaan insektisida. Aplikasi insektisida apabila dilakukan dengan tidak bijaksana akan berdampak negatif. Oleh karena itu, perlu dilakukan pengendalian hama yang ramah lingkungan sesuai konsep pengendalian hama terpadu (PHT) seperti aplikasi feromon sintetik. Penelitian ini bertujuan mengetahui tingkat parasitasi dan spesies parasitoid telur S. incertulas pada pertanaman padi yang mendapat perlakuan feromon sintetik (Z11-Hexadecenal 33%). Penelitian ini dilakukan di pertanaman padi milik petani di Desa Sukaraja, Kecamatan Rawamerta, dan Desa Sindangmukti, Kecamatan Kutawaluya, Kabupaten Karawang, Jawa Barat mulai dari Februari sampai Juni 2020. Penelitian dilakukan pada lahan 80 ha yang dibagi menjadi beberapa petak lahan. Percobaan dilakukan menggunakan rancangan acak kelompok (RAK) dengan 4 perlakuan dan 5 ulangan. Perlakuan yang digunakan yaitu perlakuan kontrol (pertanaman padi tanpa feromon) dan perlakuan feromon dengan dosis 10 dispenser/ha, 20 dispenser/ha, dan 30 dispenser/ha. Pengambilan kelompok telur dilakukan setiap 2 minggu sebanyak 4 kali. Peubah yang diamati yaitu kemunculan larva PBPK dan imago parasitoid, serta tingkat parasitisasinya. Hasil penelitian ini menunjukkan bahwa penggunaan feromon sintetik dapat memengaruhi tingkat parasitasi kelompok telur pada pengamatan 10 MST dan tingkat parasitasi butir telur pada pengamatan 6 MST, tetapi tidak memengaruhi terhadap jumlah larva PBPK yang menetas, imago parasitoid yang muncul, dan spesies parasitoid yang ditemukan., The rice production in Indonesia have significant declined due to plant pests and diseases, one of them is yellow rice stem borer (PBPK) Scirpophaga incertulas. Insecticide applications have been commonly used by farmers for controlling this pest. Unwise application of insecticides will have a negative impact. Therefore, integrated pest management (IPM) needs to be carrierd out and one of strategy is synthetic pheromone application. This research aims to determine the type of egg parasitoids and its parasitization level of S. incertulas in paddy field applied by synthetic pheromones (Z11-Hexadecenal 33%). This research was carried out in farmers' rice fields at Sukaraja Village, Rawamerta District, and Sindangmukti Village, Kutawaluya District, Karawang Regency, West Java from February to June 2020. The research was carried out on 80 Ha of land which was divided into several plots of land. The experiment was conducted using a randomized group (RBD) with 4 treatments and 5 replications. The treatments used were control treatment (rice cultivation without using pheromone) and treatment of rice planting with 10 dispenser/ha, 20 dispenser/ha, and 30 dispenser/ha. Eggs were sampled biweekly for 4 times with variables were observed of the appearance of PBPK larvae, parasitoid imago, and parasitization levels. The results of this study indicated that the use of synthetic pheromones affected the parasitization levels of egg group at 10 MST and parasitization levels of egg at 6 MST, but does not affected the number of hatched PBPK larvae, emerge parasitoids adults, and parasitoid species found.
Keyword: egg parasitoids, paddy, Scirpophaga incertulas, synthetic pheromones

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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