Judul: Population Development of Aphis gossypii G. and Predators on Monoculture and Intercropping Chili in Cikandang Village, Cikajang District, Garut
Abstrak: Aphis gossypii Glover merupakan hama penting yang menyerang tanaman cabai dengan cara menusuk dan mengisap cairan tanaman dan juga berperan sebagai vektor virus penyakit tanaman. Selain kutudaun, keberadaaan predator di lahan juga berperan penting dalam pengendalian kutudaun secara alami. Tujuan penelitian mengetahui perkembangan populasi kutudaun dan predatornya pada pertanaman cabai monokultur dan tumpang sari di Desa Cikandang, Kecamatan Cikajang, Garut. Penelitian dilaksanakan pada bulan Mei sampai dengan Juli 2021 yang meliputi pengamatan kutudaun dan predator, identifikasi, dan analisis data. Pengamatan dilakukan secara langsung dengan metode acak sistematis (jarak antar baris satu baris tanaman dan jarak dalam baris lima tanaman). Jumlah tanaman contoh setiap lahan 100 tanaman. Pengamatan kutudaun dilakukan dengan mengamati lima helai daun cabai tiap tanaman contoh sedangkan predator dilakukan dengan mengamati seluruh bagian tanaman contoh. Hasil penelitian menunjukkan bahwa populasi nimfa dan imago A. gossypii yang ditemukan pada pertanaman cabai monokultur dan tumpang sari berfluktuasi. Predator A. gossypii yang ditemukan di antaranya Episyrphus sp., Micromus sp., dan Menochilus sexmaculatus. Populasi A. gossypii pada pertanaman cabai monokultur lebih tinggi dibanding cabai tumpang sari. Begitu pula dengan populasi predatornya lebih banyak ditemukan pada pertanaman cabai monokultur dari pada cabai tumpang sari., Aphis gossypii Glover is the main pest that attacks chili plants by piercing and sucking the plant fluids and also acts as a vector for plant disease viruses. Besides the aphids, the presence of predators in the field also has an important role in the natural control of aphids. This study aimed to determine the development of aphids populations and its predators in monoculture and intercropping chili in Cikandang Village, Cikajang District, Garut. The research conducted from May to July 2021, included observations of aphids and its predators, identification, and data analysis. The observation was conducted directly by systematic random sampling (the distance of each row was one row plants and the distance in rows were five plants) and the plant sample in each field was 100 plants. The observation of aphids was conducted by observing five chili leaves for each plant sample, while for its predators were conducted by observing all parts of the plant sample. The results showed that the population of nymphs and adult A. gossypii found in the monoculture and intercropping chilies fluctuated. The predators of A. gossypii found were Episyrphus sp., Micromus sp., and Menochilus sexmaculatus. The population of A. gossypii in monoculture chili was higher than the intercropping chili. Similar for the predators population were more commonly found in the monoculture chilies than in the intercropping chilies.
Keyword: Aphis gossypii, intercropping, monoculture, predators

Judul: Study of Chili Pepper Resistance to Aphis gossypii Based on Phenotypic, Metabolomic and Molecular
Abstrak: Produksi cabai di Indonesia terkendala oleh tingginya serangan hama penyakit. Kutudaun A. gossypii menyerang cabai di dataran rendah dan menjadi vektor berbagai jenis virus tanaman. Pengendalian kutudaun secara kimiawi sudah tidak efektif dikarenakan ketahanannya terhadap beberapa bahan aktif insektisida. Penggunaan varietas tahan kutudaun pada tanaman cabai diharapkan mampu meningkatkan kualitas dari produksi cabai, menurunkan transmisi virus, serta mengurangi beban penggunaan insektisida bagi petani dan lingkungan. Adapun tujuan dari penelitian ini adalah untuk mengkaji kendali genetik ketahanan cabai terhadap infestasi kutudaun A. gossypii dari aspek fenotipik, metabolomik, serta molekuler. Tahapan penelitian terdiri atas: 1) Pengembangan metode skrining cabai terhadap infestasi hama A. gossypii; 2) Evaluasi ketahanan cabai terhadap infestasi kutudaun pada populasi bersegregasi hasil persilangan genotipe tahan dan rentan; 3) Senyawa kimia (metabolit sekunder) cabai yang terkait dengan ketahanan terhadap infestasi kutudaun melalui teknik metabolomik pada populasi bersegregasi; serta 4) Pengembangkan marka molekuler yang dapat digunakan sebagai marker assisted selection (MAS) dalam proses pemuliaan tanaman cabai ketahananterhadap infestasi kutudaun A. gossypii. Hasil penelitian menunjukkan bahwa: 1) Semua metode skrining yang digunakan efektif dan metode uji clip cage terpilih sebagai metode pengujian yang handal dan praktis dalam uji ketahanan cabai terhadap infestasi A. gossypii; 2) Genotipe cabai IPB C367 dan IPB C20 memiliki ketahanan antibiosis terhadap kutudaun A. gossypii; 3) Ketahanan cabai dikendalikan secara resesif oleh banyak gen dengan aksi gen pengendali ketahanan hama kutudaun adalah aditif-epistasis duplikat; 4) senyawa 2,4-difluorobenzoic (fluorobenzoic acid) dan senyawa 2,5- octadecadiynoic acid (fatty acid) menjadi senyawa antibiosis tanaman cabai dalam menekan populasi koloni kutudaun A. gossypii.; dan 5) Terdapat tiga perubahan basa non-synonymous yang berpotensi untuk membedakan genotipe tahan dan genotipe rentan secara molekuler terhadap infestasi kutudaun A. gossypii. Belum adanya asosiasi yang kuat antara marka molekuler dengan fenotipe tanaman dalam mengidentifikasi gen ketahanan cabai terhadap kutudaun disebabkan oleh sifat ketahanan ini memiliki kompleksitas yang tinggi karena dikendalikan oleh banyak gen (poligen) secara resesif serta terdapat peran dari aksi gen epistasis duplikat., Chili pepper production in Indonesia is constrained by high pest attacks. The cotton aphid (CA), Aphis gossypii, attachesto chilies in the lowland and is a vector for various types of plant viruses. Chemical control of aphids is no longer effective due to their resistance to several insecticidal active ingredients. The use of aphid resistant varieties on chili peppers is expected to improve the quality of chili pepper production, reduce virus transmission, and reduce the cost of using insecticides for farmers and the environment. The purpose of this study was to examine the genetic control of chili pepper resistance to CA infestation from phenotypic, metabolomic, and molecular aspects. The stages of the research consisted of: 1) the development of a chili pepper screening method for CA infestation; 2) the evaluation of chili pepper resistance to aphids in segregated populations resulting from crosses of resistant with susceptible chili genotypes; 3) the identification of chemical compounds (secondary metabolites) of chili that are related to resistance to CA through metabolomic techniques in segregated populations; and 4) the development of moleculer markers that can be used as market assisted selection (MAS) in the chili pepper breeding program for resistance to CA.
Keyword: antibiosis, clip cage, heritabilitas, no choice test, pewarisan sifat

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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