Judul: Potential of Spiders (Class Arachnida, Order Araneae) as Forest Pest Insect Predators in IPB University Campus Dramaga
Abstrak: Pengurangan penggunaan insektisida kimiawi sintetis perlu dilakukan mengingat dampak negatifnya. Salah satu metode alternatif potensial adalah pengendalian hayati dengan laba-laba. Penelitian ini bertujuan mencatat jenis Araneae dan serangga pengganggu tanaman yang dapat ditemui pada kondisi lingkungan Arboretum Fakultas Kehutanan dan Lingkungan (Arboretum) dan lahan penanaman Taman Hutan Kampus (THK) serta kelayakannya untuk digunakan dalam uji preferensi dan predasi. Sebanyak 1 jenis Araneae yaitu Trochosa alviolai (Barrion & Litsinger, 1995) dapat dengan mudah ditemukan di plot Arboretum dan layak diberikan uji predasi, sementara plot THK memiliki 3 jenis yaitu Oxyopes javanus (Thorell, 1887), Hyllus diardi (Walckenaer, 1837) dan Hippasa holmerae (Thorell 1895). Serangga pengganggu tanaman yang mudah ditemui dan layak masuk uji predasi berjumlah 4 jenis yaitu Tachytatus prolixicornis (Bergroth, 1918) pada plot Arboretum dan plot THK, kemudian jenis Gryllus sp. (famili Gryllidae) beserta 2 jenis tak teridentifikasi dari famili Acrididae dan Coreidae yang ditemukan hanya pada plot THK., The usage reduction of synthetic insecticides has to be done, considering its many negative effects. One potential alternative method is the usage of spiders. This research aims to record Araneae order members and potential pest insects that can be found under the environmental conditions of Forestry and Environment Faculty Arboretum (Arboretum) and tree planting site of Taman Hutan Kampus (THK), followed with assessment of each species’ qualifications for prey preference and predation rate tests. Only 1 Araneae species; Trochosa alviolai (Barrion & Litsinger, 1995) can be found with ease in the Arboretum plot in constrast with findings which conveniently yielded 3 species which are Oxyopes javanus (Thorell, 1887), Hyllus diardi (Walckenaer, 1837) and Hippasa holmerae (Thorell 1895). Exactly 4 species of potential pest insects were easily found on the plots and are deemed qualified for preference and predation rate tests, the insects are Tachytatus prolixicornis (Bergroth, 1918) found on both plots and 3 other insects found on the THK plot which are Gryllus sp., an unidentified species of Acrididae family, and an unidentified species of Coreidae family.
Keyword: Araneae, biological control, microclimate, pest insects, predation test

Judul: Diversity and Abundance of Canopy Spiders in Different Types of Land Use in the Taman Nasional Bukit Duabelas, Jambi Province
Abstrak: Penurunan tutupan kanopi pada kawasan hutan hujan tropis berdampak negatif terhadap keberlangsungan hidup spesies di dalamnya, tidak terkecuali Arthropoda. Salah satu kelompok Arthropoda yang berperan penting dalam keseimbangan ekosistem adalah kelompok Araneae (laba-laba). Penelitian ini bertujuan mempelajari keanekaragaman, kelimpahan, dan komposisi laba-laba kanopi pada empat tipe penggunaan lahan, mengetahui pengaruh transformasi habitat terhadap komposisi laba-laba, dan mengetahui spesies unik apa saja yang terdapat pada berbagai tipe penggunaan lahan. Pengambilan sampel dilakukan di lanskap Taman Nasional Bukit Duabelas (TNBD) pada empat tipe penggunaan lahan diantaranya : hutan, hutan karet, perkebunan karet, perkebunan kelapa sawit. Setiap tipe penggunaan lahan dipilih 4 plot inti dan masing-masing plot inti terdiri atas 3 subplot. Serangga yang berjatuhan saat proses pengasapan akan tertampung di dalam 8 wadah (1 m x 1 m) yang telah dipasang di bawah kanopi. Sampel yang berhasil dikumpulkan disortir dan diidentifikasi Di Laboratorium Pengendalian Hayati, Departemen Proteksi Tanaman, Institut Pertanian Bogor. Sampel yang dapat dikumpulkan sebanyak 1879 laba-laba, yang terdiri dari 24 famili dan 405 morfospesies. Terdapat famili yang memiliki morfospesies paling melimpah yaitu Theridiidae (89) dengan persentase sebesar 21,97% dari jumlah morfospesies yang diidentifikasi. Hasil penelitian menunjukkan tipe penggunaan lahan memengaruhi keanekaragaman dan komposisi laba-laba, akan tetapi tidak memengaruhi kelimpahan laba-laba. Keanekaragaman dan kelimpahan laba-laba lebih tinggi di hutan dan hutan karet dibandingkan perkebunan karet dan kelapa sawit. Hal ini berarti bahwa transformasi habitat berperan penting dalam keanekaragaman dan kelimpahan laba-laba kanopi pada berbagai tipe penggunaan lahan., Decrease canopy cover in tropical rain forest areas has a negative impact on the survival of the species in environment, including arthropods. One of the arthropod groups that play an important role in the ecosystem is the Araneae group (spiders). This study aims to study the diversity, abundance and composition of canopy spiders in different types of land use, to determine the effect of habitat transformation on the composition of spiders and find out what unique species are found in various types of land use. Sampling was carried out in the Bukit Duabelas National Park (TNBD) landscape on four types of land use including: forest, rubber forest, rubber plantation, oil palm plantation. For each land use type, 4 core plots were selected and each core plot consisted of 3 subplots. All arthropods that fell during the smoking process were captured by 8 containers of 1 m x 1m in size installed under the plant canopy. Samples that have been collected, sorted and identified in the Biological Control Laboratory, Department of Plant Protection, Bogor Agricultural University. Overall there were 1879 spiders collected, consisting of 24 families and 405 morphospecies. The most abundant morphospecies is Theridiidae (89) which contained 21,97% of all identified morphospecies. The results of this research showed land use type influencing the diversity and composition of spiders, but it does not influence the abundance of spiders. The diversity and abundance of spiders is higher in forest and rubber forests than rubber and oil palm plantations. This means that habitat transformation plays an important role in the diversity and abundance of canopy spiders in various land use types
Keyword: composition, deforestation, forest

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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