Judul: Pengaruh Cendawan Endofit terhadap Biologi dan Pertumbuhan Populasi Polyphagotarsonemus latus Banks (Acari: Tarsonemidae) pada Tanaman Cabai
Abstrak: Broad mite Polyphagotarsonemus latus is one of the most important pests of pepper. High population of P. latus on pepper may cause death on plants. One of the alternative environmental-friendly control methods is the use of endophytic fungi. This study aimed to know effect of the endophytic fungi on biology and population growth of broad mite on pepper. The pepper seeds were soaked in miselium suspension for 12 hours and then planted. Three weeks after seeds planting, peppers were sprayed with miselium suspension. Broad mite collected from the field were reared on pepper in the laboratory. The same age-five female adults were infested on each pepper seedling a week after last inoculation of endophytic fungi. The population growth of broad mite were observed each week for 10 weeks. In the laboratory, 50 broad mite eggs were reared on pepper leaves and observed every 6 hours until adult emergence. P. latus then paired and observed everyday until all adults dead. Life cycle, fecundity, sex ratio and adult longevity were observed. The result showed that treatment of endhophytic fungi could increase pepper seeds viability. Several kinds of endophytic fungi also suppressed population growth, elongated praoviposition period, reduced mite fecundity and increase the number of male.
Keyword: population growth, Polyphagotarsonemus latus, endophytic fungi, pepper

Judul: Pengaruh Cendawan Endofit terhadap Biologi dan Statistik Demografi Wereng Batang Cokelat
Abstrak: Endophytic fungi is an endosymbiont that lives within host plant tissues without causing any visible symptom of disease. This type of fungus are important as mediators in plant-herbivore interactions. Endophytic fungi are known to enhance resistance of host plant against insect herbivores mainly by productions of various alkaloid-based defensive compounds in the plant tissue or through alterations of plant nutritional quality. This study was conducted as an attempt to gain information on the effect of Nigrospora sp4 on the biology and life history of of brown plant hopper (BPH). Nigrospora sp4 culture (in powder form), were provided by Plant Clinic of Bogor Agriculture University, and was used to inoculate the fungi to the rice seeds. The effect of endophyte infected and endophyte-free plants were measured on the survival and development of Nilaparvata lugens Stál, a major pest in rice. Endophyte infected plants showed resistance to N. lugens in the form of significant increase in eggs and early nymphs mortality. Another effect of endophytic fungi which was also observed on this study were nymphal development, life cycle, preovipositional period as well as age at first reproduction. The overall result showed that Nigrospora sp4 has an affect toward population growth of N. lugens in laboratory scale and artificial inoculation of endophytes could be a useful method to protect rice plants from N. Lugens. This result could be used to develop alternative ecologically safe control strategies.
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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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