Judul: Mortality and Feeding Inhibition Activities of Suicide Tree (Cerbera odollam Gaertn) Fruit Extract on Spodoptera frugiperda
Abstrak: Spodoptera frugiperda (Lepidoptera: Noctuidae) merupakan hama invasif yang menyerang tanaman jagung di Indonesia. Serangan hama ini dapat menimbulkan kerugian secara ekonomi bagi petani jagung terutama di negara- negara produsen jagung. Untuk itu perlu dipikirkan langkah-langkah pengendalian yang efektif, efisien, dan mudah dilakukan serta aman terhadap lingkungan. Salah satu pengendalian yang efektif dan efisien serta ramah lingkungan yaitu dengan menggunakan insektisida nabati. Buah bintaro (Cerbera odollam Gaertn) merupakan salah satu tumbuhan yang berpotensi dapat digunakan sebagai pestisida nabati karena memiliki kandungan senyawa metabolit sekunder seperti polifenol, saponin, tanin, steroid, terpenoid, dan alkaloid. Penelitian ini bertujuan menguji pengaruh ekstrak buah bintaro terhadap mortalitas dan penghambatan aktivitas makan pada larva S. frugiperda instar I. Pengujian mortalitas menggunakan metode residu pada daun. Ekstrak tanaman dihasilkan dengan metode ekstraksi maserasi menggunakan dua pelarut yang berbeda yaitu heksana dan etil asetat. Berdasarkan hasil analisis probit menggunakan program POLO-PC ekstrak yang paling toksik yaitu dengan perlakuan heksana dengan LC50 sebesar 0,246% dan LC95 sebesar 1,528% pada 72 jam setelah perlakuan (JSP). Pada konsentrasi tertinggi masing- masing perlakuan (1,46% pada pelarut heksana dan 5,01% pada etil asetat) mampu menyebabkan kematian berturut-turut sebesar 92% dan 100% pada 72 JSP. Uji penghambatan aktivitas makan menggunakan metode pilihan (choice method) dengan tiga taraf konsentrasi yaitu LC15, LC35, dan LC50. Hasil pengamatan menunjukkan bahwa kedua perlakuan mempunyai pengaruh terhadap penghambatan aktivitas makan pada larva. Masing-masing pada LC50, heksana mampu menghambat sebesar 83,38% dengan kriteria kuat, sedangkan pada etil asetat sebesar 62,21% dengan kriteria sedang., Spodoptera frugiperda (Lepidoptera: Noctuidae) is an invasive pest that attacks maize in Indonesia. This pest attack can cause economic losses for corn farmers, especially in corn-producing countries. For this reason, it is necessary to think about control measures that are effective, efficient, easy to implement, and safe for the environment. One of the effective and efficient as well as environmentally friendly controls is by using botanical insecticides. Suicide tree (Cerbera odollam Gaertn) fruit is a plant that has the potential to be used as a botanical pesticide because it contains secondary metabolites such as polyphenols, saponins, tannins, steroids, terpenoids, and alkaloids. This study aimed to examine the effect of suicide tree fruit extract on mortality and feeding inhibition activities against first instar S. frugiperda larvae. Mortality assay used the residue method on leaves. Plant extracts were obtained by maceration extraction method using two different solvents namely n-hexane and ethyl acetate. Based on the results of probit analysis using the POLO-PC program, the most toxic extract was n-hexane extract with LC50 and LC95 of 0.246% and 1.528% at 72 hours after treatment (HAT), respectively. The highest concentrations of each extract treatment (1.46% for n- hexane and 5.01% for ethyl acetate) were able to cause death by 92% and 100% at 72 HAT, respectively. Feeding inhibition activity assay using choice method with three concentration levels, namely LC15, LC35, and LC50 showed that all treatments inhibited feeding activity of larvae. N-hexane and ethyl acetate extracts at LC50 inhibited 83.38% with strong criteria and 62.21% with moderate criteria of larvae feeding activity, respectively.
Keyword: hama invasif, insektisida nabati, metabolit sekunder, botanical insecticides, invasive pests, secondary metabolites

Judul: Efektivitas Ekstrak Buah Bintaro (Cerbera odollam) sebagai Larvasida Lalat Rumah (Musca domestica)
Abstrak: Cerbera odollam is known as bintaro in Indonesia. It is a poisonuous plant which is found at seaside, mangrove forest, and widely used to hold a high wave, prevent landslide, and as decorated plant. Bintaro has potential as a natural larvicide but there is no research about using bintaro to control Musca domestica’s larvae in Indonesia. The objective of this research is to measure effectiveness of bintaro as a larvicide of M. domestica. The parts of bintaro which is used for research were seeds and barks. Seeds and barks were extracted by methanol 96% and diluted by aquabidest. The concentration of extract divided to some groups, there was negative control which is only given aquadest, seeds extract 10, 30 , 60, 80 g/100 ml and barks extract 80 g/100 ml. Seeds and barks extract were tested to larvae groups. The result showed that seeds and barks extract of Bintaro can be used for larvicide. Seeds extract was more effective than barks extract. Phytochemical screening showed that alkaloids, flavonoids, saponins, tannins, and steroids were the secondary metabolite compounds contained in seeds and barks.
Keyword: seeds, Musca domestica, larvicide, Cerbera odollam, barks

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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