Judul: Pengaruh Provenansi dan Kondisi Pohon Sengon (Paraserianthes falcataria (L) Nielsen) terhadap Biologi Hama Boktor (Xystrocera festiva Pascoe) pada Artificial
Abstrak: Recently, Sengon tree (Paraserinthes falcataria (L) Nielsen) cultivation in the form of monoculture has been increasing with the increase of demand and price of sengon timber. Sengon tree has also been used extensively in the rehabilitation effort of degraded forest and land. Sengon cultivation in the form of monoculture, however has faced serious problem of insect attack, especially stem borer, namely Boktor (Xystrocera festiva Pascoe). The pest problem requires an appropriate control measures, because it can destroy a plantation. An effective and efficient control method has not been developed, however, due to lack of knowledge on insect biology and physiology. This report describes a study on boktor larvae conducted in Forest Entomology Laboratory, Faculty of Forest, IPB, starting February to April 2006. The purpose of study were to investigate the effect of different provenance and tree condition in an artificial diet on the growth and preference of boktor larvae. Results of the study could give information on the biology and behavior of boktor larvae, as well as the possible resistant provenance against the pest.
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Judul: Pengaruh Provenan Sengon Terhadap Perkembangan Larva Boktor (Xystrocera Festiva Thoms) Dalam Makanan Buatan (Artificial Diet)
Abstrak: Problem which is most commonly encountered in the management of sengon plantation forest, at present was the attack by stem borer insect Xystrocera festiva Thoms, a pest which is more often referred to as boktor, uter-uter, wowolan, and engkes-engkes. Up to now, the effective and efficient specific control for boktor pest, has not been discovered yet. One method which had ever been practiced was slicing the sengon bark and discarding the boktor larvae existing inside the tree. However, this practice will damage the physiological process of sengon trees, and this will in turn reduce the quality and price of sengon wood. One of the cause which makes the control of boktor has not been fully successful is the lack of knowledge concerning this insect, particularly in its larval stadium (the damaging phase), when this insect larvae live under the bark, which makes the study of biology and physiology of the insect difficult. For overcoming this phenomenon, a laboratory research was conducted where the boktor insects were reproduced and observed while being raised using artificial diet. This research was useful for obtaining information on the behavior and life cycle of boktor. The objectives of this research were learning the effects of provenance, tree health condition (sick or healthy condition of trees) and artificial diet on the growth of boktor larvae, and seeking the appropriate composition of artificial diet for boktor larvae. Materials used in this research were sengon wood powder from Kediri and Subang provenance with two kinds of tree condition (sick and healthy trees) while each of them had undergone freeze drying process, yeast extract, streptomycin, sucrose, agar, aquadest, vitamin C, vitamin B, benzoate, NaCl, dolomite, olive oil, and small sized boktor larvae (1.4 – 2.4 cm). The parameters observed and measured were larvae weight, weight of consumed food by the boktor larvae, larvae length, and diameter of boktor larvae head. Observation and measurements were conducted each week for 8 weeks, while conducting also food change. Results of analysis of variance showed that the provenance factor exhibited the greatest and significant effect on larvae growth (larvae length, diameter of larvae head) and amount of food consumed by the boktor larvae. On the other hand, factor of tree condition did not create significant effect on all parameters for 7 weeks. Factor of tree condition was seen to have effect on week 8. Patterns of average growth of larvae weight and length, for all treatments showed significant decrease in week-5 and 6. This phenomenon occurred because at week 5 and 6, many larvae underwent ecdysis (molting). Results of Duncan test showed that Subang provenance gave the best effect. The best growth of boktor larvae, namely those of Subang provenance had larvae length increment of 2.53 mm and larvae head diameter increment of 0.166 mm. Feeding behavior of boktor larvae during the laboratory research, using artificial diet, was similar with that in the field. Keywords: sengon, artificial diet, boktor
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Judul: Invers Drazin dari Matriks Toeplitz Singular
Abstrak: Matriks Toeplitz adalah matriks yang setiap unsur pada diagonal utama bernilai sama dan setiap unsur pada subdiagonal yang bersesuaian dengan diagonal utama juga bernilai sama. Matriks singular adalah matriks yang tidak bisa ditentukan inversnya. Akan tetapi, dapat diupayakan untuk ditentukan inversnya menggunakan invers matriks yang diperumum. Invers Drazin merupakan salah satu jenis invers matriks yang diperumum. Pada karya ilmiah ini ditentukan invers Drazin dari matriks Toeplitz singular dengan menggunakan metode Leverrier Faddeev. Kemudian, ditentukan invers Drazin dari matriks Toeplitz singular yang direpresentasikan sebagai penjumlahan segitiga bawah dan segitiga atas matriks Toeplitz berdasar pada teorema Gohberg dan Semencul., Toeplitz matrix is a matrix in with element on the main diagonal has the same value and on the subdiagonal corresponding to the main diagonal also has the same value. Singular matrix is a matrix that has no inverse. However, it can be attempted to determine the inverse using a generalized inverse matrix. Inverse Drazin is a type of generalized matrix inverse. This paper discussed the inverse Drazin for a singular Toeplitz matrix using the Leverrier Faddeev method. Then, the Drazin inverse of the singular Toeplitz matrix which is represented as a sum of products of lower and upper triangular Toeplitz matrix based on Gohberg and Semencul theorem.
Keyword: inverse Drazine, singular Toeplitz matrix