Judul: Biology and population abundance of spider mite tetranychus kanzawai (Acari: Tertanychidae) on Two cultivars of Jatropha curcas
Abstrak: Spider mite Tetranychus kanzawai is one of the most important pests attacking leaf of Jatropha curcas. Study was conducted with the objectives to elucidate life history parameters and abundance of spider mite on two Jatropha curcas cultivars. Field studies were carried out in BALITTRI Pakuwon Sukabumi, and laboratory experiments were conducted at the Department of Plant Protection, Bogor Agricultural University, from June to November 2008. Cultivars significantly affected some life history parameters of the spider mite. Spider mite reared on IP1 cultivar have longer oviposition period and higher fecundity than those on IP2 (7.00 days and 25.56 eggs against 5.00 days and 10.00 eggs). Intrinsic rate of increase was also higher on IP1. However, field studies indicated that the spider mite were less abundant on this cultivar. These might be due to the presence of other arthropods which were higher on IP1. In general, the highest population of spider mite occurred in August and the lowest in October- November.
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Judul: . The Strategy of Using a Predatory Mite, Neoseiulus  longispinosus Evans (Phytoseiidae), to Control Tetranychus kanzawai Kishida (Tetranychidae) on Cassava Plant
Abstrak: Tetranychus kanzawai Kishida (Acari: Tetranychidae) merupakan hama penting yang banyak menyebabkan kerugian pada beberapa jenis tanaman di Indonesia. Pengendalian tungau ini umumnya dilakukan secara kimiawi dengan akarisida. Penggunaan akarisida yang intensif dan tidak bijaksana dapat memicu munculnya dampak negatif. Metode alternatif yang lebih aman untuk mengendalikan hama ini perlu terus dikembangkan, salah satunya dengan memanfaatkan tungau predator sebagai agen pengendalian hayati. Salah satu musuh alami yang penting bagi T. kanzawai adalah tungau predator famili Phytoseiidae, di antaranya Neoseiulus dan Phytoseiulus. Neoseiulus longispinosus Evans (Acari: Phytoseiidae) merupakan tungau predator tipe II atau predator generalis yang memiliki preferensi terhadap tungau Tetranychidae. Penelitian ini bertujuan menentukan rasio dan waktu pelepasan N. longispinosus yang paling efektif dalam mengendalikan T. kanzawai pada tanaman ubi kayu. Percobaan menggunakan rancangan strip plot dengan tiga ulangan. Rasio pelepasan predator:mangsa adalah faktor A dengan empat taraf yaitu rasio pelepasan predator:mangsa 0 : 5, 1 : 5, 2 : 5, dan 3 : 5. Waktu pelepasan predator adalah faktor B dengan tiga taraf, yaitu satu, dua, dan tiga minggu T. kanzawai diinfestasi. (tiga minggu setelah tanam (MST), 4 MST, dan 5 MST). Infestasi T. kanzawai dilakukan pada tanaman ubi kayu kultivar Mentega saat tanaman berumur 2 MST. Pengamatan pengaruh pelepasan predator N. longispinosus terhadap intensitas serangan dan populasi T. kanzawai dilakukan saat tanaman berumur 6 MST. Pelepasan predator N. longispinosus dapat menekan populasi dan intensitas serangan T. kanzawai pada tanaman ubi kayu. Rasio predator:mangsa (N. longispinosus: T. kanzawai) yang optimum untuk menekan populasi T. kanzawai adalah rasio 2:5 dan 3:5. Penekanan populasi T. kanzawai tertinggi terjadi pada perlakuan pelepasan predator satu minggu setelah infestasi tungau hama. Pelepasan N. longispinosus hanya mampu menurunkan intensitas serangan T. kanzawai pada tanaman ubi kayu paling tinggi sebesar 8,55%., Tetranychus kanzawai Kishida is an important pest that causes a lot of damage to several types of crops in Indonesia. The control of this mite is generally carried out chemically using acaricide. The intensive use of acaricide triggers many negative impacts. Alternative ways for the control this pest are needed, and one of which is by using predatory mites as biological control agents. Some important natural enemies of T. kanzawai are phytoseiid mites, including Neoseiulus and Phytoseiulus. Neoseiulus longispinosus Evans (Acari: Phytoseiidae) is a type II predator or generalist predator which has preference for tetranychid mites. This study was aimed to determine the most effective release ratio and time of N. longispinosus in controlling T. kanzawai in cassava plants. The experiment was carried out using a strip plot design with three replications. The predator release ratio to prey as the factor A consisting of four levels, namely 0:5, 1:5, 2:5, and 3:5 of predator:prey ratio. Predator release time as factor B with three levels, namely one, two, and three weeks after T. kanzawai release (three weeks after planting (WAP), 4 WAP, and 5 WAP). Infestation of T. kanzawai was carried out on cassava plant cultivar Mentega when the plants were 2 WAP. Observations on the effect of N. longispinosus release on the attack intensity and population of T. kanzawai were carried out at 6 WAP. The results in
Keyword: biological control, predatory mite, predator to prey ratio, spider mite

Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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