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: Sebaran Kelompok Telur Penggerek Batang Padi Kuning dan Parasitoidnya pada Pertanaman Padi di Kabupaten Indramayu
Abstrak: Tanaman padi merupakan salah satu komoditas tanaman pangan utama di Indonesia. Salah satu kendala yang menjadi faktor penghambat dalam upaya peningkatan produktivitas padi adalah kehilangan hasil yang disebabkan oleh serangan hama penggerek batang padi kuning (Scirpophaga incertulas) yang dapat menyerang tanaman padi pada fase vegetatif dan generatif. Penelitian ini bertujuan mengetahui sebaran kelompok telur penggerek batang padi kuning dan parasitoidnya pada pertanaman padi di Kecamatan Losarang, Terisi, dan Cikedung, Kabupaten Indramayu, Jawa Barat. Penelitian yang dilaksanakan pada bulan Desember 2021 hingga Februari 2022 meliputi pengumpulan kelompok telur di persemaian, wawancara dengan petani dan pemilik kios pestisida untuk mengetahui hubungan antara distribusi kelompok telur dengan intensitas penggunaan pestisida. Hasil penelitian menunjukkan bahwa sebaran kelompok telur di tiga kecamatan tidak berbeda nyata. Jumlah kelompok telur paling banyak didapatkan di Kecamatan Losarang, sementara itu parasitoid terbanyak ditemukan di Kecamatan Cikedung. Parasitoid yang ditemukan di tiga kecamatan yaitu Telenomus dignoides (Hymenoptera: Scelionidae), Telenomus dignus, Telenomus remus, Telenomus rowani, Trichogramma japonicum (Hymenoptera: Trichogrammatidae), dan ditemukan satu hiperparasitoid Cotesia sp. (Hymenoptera: Braconidae). Hasil penelitian ini diharapkan dapat berkontribusi dalam implementasi PHT di Indonesia., Rice plant is one of the main food crop commodities in Indonesia. One of the obstacles in increasing rice productivity is the attack of the yellow rice stem borer (Scirpophaga incertulas). This pest can attack rice plants on the vegetative and the generative phases causing loss of yield. This study aimed to determine the distribution of egg groups of the yellow rice stem borer and their parasitoids on rice in the districts of Losarang, Terisi, and Cikedung, Indramayu Regency, West Java. The study was conducted from December 2021 to February 2022. This study included collecting egg groups in nurseries and interviewing farmers and pesticide kiosk owners to determine the relationship between egg group distribution and the intensity of pesticide use. The results showed that the distribution of egg groups in the three sub-districts was not significantly different. The highest number of egg groups was in Losarang district, while the highest number of parasitoids was found in Cikedung district. The parasitoid species found in three sub-districts were Telenomus dignoides (Hymenoptera: Scelionidae), T. dignus, T. remus, T. rowani, Trichogramma japonicum (Hymenoptera: Trichogrammatidae), and one hyperparasitoid was found Cotesia sp. (Hymenoptera: Braconidae). This research results are expected to contribute in the implementation of IPM in Indonesia.
Keyword: generative phase, hyperparasitoid, kiosk, pesticides, vegetative phase

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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