Judul: Tingkat Serangan Plutella xylostella dan Parasitisasi Diadegma semiclausum pada Tanaman Kubis Organik dan Konvensional
Abstrak: Kubis (Brassica oleracea) merupakan salah satu komoditas sayuran yang banyak dikonsumsi di Indonesia dan memiliki nilai ekonomi yang cukup tinggi. Produktivitas kubis di Indonesia masih tergolong rendah, salah satunya disebabkan hama P. xylostella. Pengendalian hama ini banyak dilakukan dengan aplikasi pestisida yang dapat menekan populasi musuh alami, terutama D. semiclausum yang merupakan parasitoid penting P. xylostella. Informasi mengenai tingkat serangan P. xylostella dan parasitisasi D. semiclausum dalam sistem budidaya organik dan konvensional dapat digunakan dalam menentukan sistem budidaya yang akan digunakan. Penelitian ini bertujuan mendapatkan informasi mengenai populasi dan tingkat serangan P. xylostella, tingkat parasitisasi D. semiclausum dan kelimpahan artropoda tanah pada budidaya kubis organik dan konvensional. Rata rata populsi P. xylostella pada pertanaman kubis organik yaitu 5,1 individu/tanaman, sedangkan pada pertanaman kubis konvensional 9,8 individu/tanaman. Rata-rata luas serangan dan intensitas kerusakan pada pertanaman kubis organik yaitu 93% dan 15,55%, sedangkan pada pertanaman kubis konvensional 83% dan 17,90%. Rata-rata tingkat parasitisasi D. semiclausum pada pertanaman kubis orgnaik yaitu 20,91%, sedangkan pada pertanaman kubis konvensional 10,39%. Jumlah individu artropoda tanah pada pertanaman kubis organik lebih banyak dibandingkan pada pertanaman kubis konvensional dengan jenis artropoda yang sama meliputi Hymenoptera, Coleoptera, Dermaptera, Orthoptera, Diptera, dan Stylommatophora, Cabbage (Brassica oleracea) is a vegetable commodity widely consumed in Indonesia and has high economic value. The productivity of cabbage in Indonesia is still low, one of which is caused by the infestation of P. xylostella. The control of this pest is mostly carried out by applications of pesticides which can suppress the population of natural enemies, especially D. semiclausum which is an important parasitoid of P. xylostella. Information about the infestation level of P. xylostella and parasitization of D. semiclausum in organic and conventional cabbage cultivation systems can be used in determining the cultivation system that will be used. The aims of this reaserch were to obtain information about the population and infestation level of P. xylostella, level of parasitization of D. semiclausum, and the abundance of soil arthropods in organic and conventional cabbage cultivation. Population of P. xylostella in organic cultivation was 5.1 individuals/plant, while in conventional cultivation was 9.8 individuals/plant. The infestation level and the plant damage caused by P. xylostella in organic cultivation were 93% and 15.55%, while in conventional cultivation were 83% and 17.90%. The parasitization level of D. semiclausum in organic cultivation was 20.91%, while in conventional cultivation was 10.39%. The diversity of soil arthropods in organic cabbage cultivation and conventional cabbage cultivation was similar. The arthropods collected from the both cabbage cultivations were Hymenoptera, Coleoptera, Dermaptera, Orthoptera, Diptera, dan Stylommatophorabundance. The abundance of soil arthropods in organic cabbage cultivation was higher than in conventional cabbage cultivation.
Keyword: budi daya konvensional, budi daya organik, D. semiclausum, kubis, P. xylostella

Judul: Keanekaragaman dan Tingkat Parasitisasi Parasitoid Plutella xylostella dan Crocidolomia pavonana (Studi Pustaka)
Abstrak: Kubis (Brassica oleracea L. var. capitata) merupakan salah satu komoditas hortikultura penting dan memiliki nilai ekonomi yang cukup tinggi di Indonesia. Salah satu faktor yang menyebabkan penurunan produksi kubis adalah adanya serangan hama tanaman yang dapat mengurangi kualitas dan kuantitas hasil panen. Plutella xylostella and Crocidolomia pavonana merupakan hama penting pada pertanaman kubis. Penelitian ini bertujuan untuk mengumpulkan informasi tentang keanekaragaman parasitoid pada P. xylostella dan C. pavonana serta tingkat parasitisasinya yang telah dilaporkan dalam beberapa penelitian. Metode penelitian yang dilakukan adalah kajian pustaka yang berhubungan dengan parasitoid pada P. xylostella and C. pavonana. Sumber pustaka dicari melalui internet, yaitu Google, Google Schoolar, Researchgate dan sumber pustaka lain yang relevan dengan penelitian ini. Hasil penelusuran pustaka menunjukkan terdapat lima famili dari Ordo Hymenoptera yang dilaporkan menjadi parasitoid pada P. xylostella. Lima famili tersebut adalah Braconidae, Eulophidae, Chalcididae, Ichneumonidae dan Trichogrammatidae, dengan total 46 spesies parasitoid. Hasil penelusuran pustaka menunjukkan terdapat tiga famili dari Ordo Hymenoptera dan satu famili dari Ordo Diptera yang dilaporkan menjadi parasitoid pada C. pavonana. Famili dari Ordo Hymenoptera tersebut adalah Braconidae, Ichneumonidae dan Trichogrammatidae dan famili dari Ordo Diptera adalah Tachinidae. Sebanyak 12 spesies parasitoid dilaporkan telah memarasit C. pavonana., Cabbage (Brassica oleracea L. var. capitata) is an important vegetable commodity and has a high economic value in Indonesia. One of the declining factors in cabbage production is the attack of plant pests which can reduce the quality and quantity of the yields. Plutella xylostella and Crocidolomia pavonana are the main pests in cabbage cultivation. This study aims to summarize information about the diversity of parasitoids in P. xylostella and C. pavonana as well as the level of parasitization that has been reported in several studies. The research method used was literature review related to parasitoids on P. xylostella and C. pavonana. Library sources searched through the internet include Google, Google Schoolar, Researchgate and other literature sources relevant to this research. The results of literature search show that there were five families of the Order Hymenoptera which were reported to be P. xylostella parasitoid. The five families were Braconidae, Eulophidae, Chalcididae, Ichneumonidae and Trichogrammatidae, with a total of 46 parasitoid species. The literature search results on the parasitoid of C. pavonana show that there were three families of the Order Hymenoptera and one family of the Order Diptera which were reported to be parasitoid of C. pavonana. The families of the Order Hymenoptera were Braconidae, Ichneumonidae and Trichogrammatidae and the family of the Order Diptera was Tachinidae. A total of 12 parasitoid species were reported to parasitize C. pavonana.
Keyword: biological control, cabbage cultivation, insecticide resistance, pest

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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