Judul: Diversity and Abundance of Insect Pollinators in Different Land Use Types in Jambi, Sumatra
Abstrak: Indonesia is one of the tropical countries with high biodiversity. Recently, the biodiversity of plants and animals is declining due to forest converting to settlements, mines, agricultures, and plantations. In Central Sumatra including Jambi, annual deforestation rate reaches 3.2%-5.9%. Converting natural landscapes to agricultural land affects insects biodiversity, including insect pollinators. The research aimed to study diversity and abundance of insect pollinators in different land use types, i.e. oil palm plantation, rubber plantation, and jungle-rubber in Jambi, Sumatra. Observation and collection of insect pollinators were conducted from November until December 2012 at Bejubang, Batanghari regency, Jambi province. Insect observations were conducted in understory plants at three land use types, i.e. oil palm plantation, rubber plantation, and jungle-rubber. Scan sampling method was employed to explore the diversity and abundance of insect pollinators at 08.00-10.00 and 14.00-16.00 in sunny days. This study consist of found 1308 individuals of insect pollinators, belonging to 54 species,7 families, and 3 orders (Hymenoptera, Diptera, and Lepidoptera). Number of species and individual of insect pollinators found in oil palm plantation (43 species, 561 individuals) and rubber plantation (40 species, 650 individuals) were higher than jungle-rubber (7 species, 97 individiuals). Giant honey bee (Apis dorsata) and stingless bee (Trigona sp. (=aff. T. planifrons)) were abundant in oil palm plantation, while stingless bee (T. laeviceps) and small carpenter bee (Ceratina lieftincki) were abundant in rubber plantation. Whereas, hoverfly (Syrphidae sp5) was abundant in the jungle-rubber. The abundance and species richness of insect pollinators in the morning were higher than in the afternoon. Diversity and evenness of insect pollinators in oil palm and rubber plantations were higher than jungle-rubber. The abundant of flower of understory plants in oil palm and rubber plantations indicated insect pollinators forage in those locations. Meanwhile, jungle-rubber and rubber plantations were prefered by insect pollinators for nest building, because there were many large trees, branches, and broken twigs. The insect pollinators community in oil palm plantation and rubber plantation were more similar than in oil palm plantation and jungle-rubber, or in rubber plantation and jungle-rubber.
Keyword: Apidae, Halictidae, insect pollinators, Megachilidae, Syrphidae

Judul: Diversity of Dominant Diptera in Tree Canopies in Lowland Rainforest Landscapes, Jambi Province
Abstrak: Hutan hujan tropis dataran rendah di wilayah Jambi mengalami penurunan tutupan kanopi secara masif akibat alih fungsi lahan menjadi perkebunan monokultur. Konversi lahan menyebabkan penurunan kelimpahan dan kekayaan spesies serangga seperti semut, Hymenoptera parasitoid, dan kumbang. Sampai saat ini, belum ada laporan penelitian mengenai dampak konversi lahan terhadap kelimpahan dan kekayaan spesies Diptera di Sumatra, khususnya di Bukit Duabelas dan Hutan Harapan, Jambi. Penelitian ini bertujuan mengetahui dampak konversi hutan menjadi perkebunan karet dan sawit, pengaruh musim, habitat riparian, dan lanskap terhadap kelimpahan dan kekayaan spesies Diptera kanopi, khususnya di Jambi. Pengambilan sampel dilakukan dengan teknik pengasapan di empat tipe penggunaan lahan (hutan alami, hutan karet, perkebunan karet, dan perkebunan sawit), dua musim (kemarau dan hujan), dua habitat (riparian dan nonriparian), dan dua lanskap (Bukit Duabelas dan Hutan Harapan). Jumlah Diptera kanopi yang diperoleh yaitu 42 333 individu dari 29 subfamili, 109 genus, dan 947 spesies yang diketahui. Penelitian ini menunjukkan bahwa konversi hutan menjadi perkebunan menurunkan kelimpahan dan kekayaan spesies Diptera kanopi. Kelimpahan Diptera kanopi terendah ditemukan pada perkebunan sawit, sedangkan kekayaan spesies terendah ditemukan pada perkebunan karet. Komposisi Diptera kanopi paling mirip yaitu pada hutan alami dan hutan karet, sedangkan komposisi Diptera kanopi paling berbeda ditemukan pada hutan alami dan perkebunan sawit. Musim hujan meningkatkan kelimpahan dan kekayaan spesies Diptera kanopi. Keberadaan habitat riparian meningkatkan kelimpahan Diptera kanopi, tetapi tidak memengaruhi kekayaan spesiesnya. Lanskap Bukit Duabelas memiliki kelimpahan dan kekayaan spesies Diptera kanopi yang lebih tinggi daripada Hutan Harapan., The lowland tropical rainforests in Jambi have experienced a massive decline in canopy cover, a direct consequence of land conversion into monoculture plantations. This drastic change in land conversion reduced the abundance and species richness of canopy insects, including ants, butterflies, parasitoid wasps, and beetles. It is crucial to note that, to date, research has yet to be conducted on the abundance and species richness of Diptera in Sumatra, particularly in Bukit Duabelas and Harapan Rainforest, Jambi, in the context of land conversion. This research aims to determine the impact of forest conversion into rubber and oil palm plantations, the effect of seasons, riparian habitats, and landscapes on the abundance and species richness of canopy Diptera, especially in Jambi. Canopy Diptera samples were collected using fogging in four land-use systems (forest, jungle rubber, rubber plantation, and oil palm plantation), two seasons (dry and rainy), two habitats (riparian and nonriparian), and two landscapes (Bukit Duabelas and Harapan Rainforest). A total of 42 333 individuals were collected and identified to morphospecies level, belonging to 10 families, 29 subfamilies, 109 genera, and 947 known species. The finding of this study indicates that the conversion of forests into plantations reduces the abundance and species richness of canopy Diptera. The lowest abundance of canopy Diptera was found in oil palm plantations, while the lowest species richness was in rubber plantations. Canopy Diptera in forests has a similar composition to those in jungle rubbers, while it was most different in oil palm plantations. The rainy season increases the abundance and the species richness of canopy Diptera. The riparian habitat increased the abundance of canopy Diptera but did
Keyword: arboreal insects, biodiversity, flies, food web, mosquitos

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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