Judul: Toksisitas Ekstrak Tephrosia vogelii dan Alpinia galanga terhadap Myzus persicae pada Tanaman Cabai
Abstrak: Red pepper (Capsicum annum) is one of the important agricultural commodities in Indonesia, but the production is still fluctuated. One of factor that cause the decline in productivity of red pepper is a disturbance of pests and diseases. Aphids Myzus persicae is one of the important pests on red pepper cultivation because it can cause loss of up to 80%. Botanical insecticide is one of alternative pest control agents which is biodegradable, safer than synthetic pesticides, and environmentally friendly. The objective of this study was to determine the effectiveness of two types of plant extracts as insecticides against M. persicae on red pepper (Capsicum annum) using the residual in plants methods and of systemic effects methods. Extracts used were Tephrosia vogelii and Alpinia galanga, each extract was tested using the residual and systemic methods. Extracts of T. vogelii showed a higher toxicity using both the residual and systemic methods with each LC95 values at 72 hours after treatment were 16 and 12 times more toxic than extracts of A. galanga. Systemic method was more efficient than the residual method. Testing of T. vogelii extract using systemic effect method LC95 8.5 times lower than using residual method on plant, as well as the test of A. galanga extract that the systemic method show more toxic than residual method.
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Judul: Keefektifan Ekstrak Annona muricata Linn. dan Tephrosia vogelii Hook. terhadap Mortalitas Bemisia tabaci Genn. pada Tanaman Cabai
Abstrak: Bemisia tabaci merupakan salah satu spesies kutu kebul yang dapat mengakibatkan kerusakan langsung maupun kerusakan tidak langsung pada tanaman. Kerusakan langsung mengakibatkan gejala bintik klorosis pada daun sehingga dapat mengurangi kandungan klorofil. Sementara itu, kerusakan tidak langsung berkaitan dengan peran B. tabaci sebagai vektor virus yang dapat menyebabkan penyakit pada tanaman inang. Virus gemini merupakan salah satu virus penyebab penyakit kuning pada tanaman cabai di Indonesia yang ditularkan oleh B. tabaci. Untuk itu diperlukan tindakan untuk mengendalikan hama tersebut. Pengendalian hama menggunakan sumber daya hayati merupakan salah satu altenatif pengendalian karena termasuk komponen Pengendalian Hama Terpadu (PHT) yang aman terhadap lingkungan. Oleh karena itu dilakukan penelitian yang bertujuan untuk mempelajari keefektifan ekstrak Annona muricata dan Tephrosia vogelii untuk mengendalikan B. tabaci. Penelitian dilakukan dengan menggunakan dua ekstrak tanaman, yaitu A. muricata dan T. vogelii dengan enam konsentrasi yaitu 1%, 0.5%, 0.25%, 0.125%, 0.0625%, dan kontrol dengan lima kali ulangan untuk setiap perlakuan. Hasil penelitian menunjukkan bahwa semakin tinggi perkembangan serangga uji, tingkat mortalitas semakin rendah. Nimfa instar satu menunjukkan fase yang paling efektif untuk dilakukan tindakan pengendalian. Berdasarkan nilai LC50, ekstrak T. vogelii lebih efektif dalam mengendalikan nimfa instar satu, sedangkan berdasarkan nilai LC75 dan LC90 ekstrak A. muricata lebih efektif dibandingkan ekstrak T. vogelii. Ekstrak A. muricata dan T. vogelii pada konsentrasi 1% berpengaruh terhadap lama perkembangan berbagai fase B. tabaci
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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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