Judul: Host acceptance and food efficiency by Epilachna vigintioctopunctata on several host plants
Abstrak: Epilachna vigintioctopunctata (Fabricius) (Coleoptera: Coccinellidae) is commonly known as hadda beetle. This insect is a phytophagous and causes a serious pest and built a tremendous damage to solanaceaeous crops. The suitability of a certain host plant could affect on feeding activity and digestibility of food that support insect growth and development. Recently, food acceptance and suitability on several varieties of host plants by E. vigintioctopunctata has not been reported in Indonesia. The objective of this research was to investigate the host acceptance and food efficiency by E. vigintioctopunctata on several host plants. Both larvae and adults bite on six species of leaves Solanum melongena, S. tuberosum, Lycopersicon esculentum, Physalis angulata, Cucumis sativus, and Cucurbita pepo. The larvae and adult beetles mostly fed on S. melongena with the areal leaf consumed 6.75 and 1.771 cm2/insect/day, followed by L. esculentum, 4.416 and 1.35 cm2/insect/day. The average rate of consumption on L. esculentum by early 4th instar larvae was 1.5 x 105 μg/insect/day higher than S. melongena was 1.0 x 105 μg/insect/day. On the other hand, the average growth rate and efficiency of conversion of digested food were 3723.7 μg/insect/day and 43.17% higher than in S. melongena than L. esculentum were 2984.8 μg/insect/day and 19.94% respectively. This beetle has low consumption but high efficiency of utilization food on S. melongena.
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Judul: Siklus Hidup dan Demografi Kumbang Lembing Henosepilachna vigintioctopunctata Fabricius (Coleoptera: Coccinellidae) Pada Tanaman Inang yang Berbeda
Abstrak: Phytophagous lady beetle Henosepilachna vigintioctopunctata Fabricius is a serious pest of solanaceous crops, such as eggplants and potatoes. The beetles distributes from sub temperate of Asia to the tropics of Indonesia. The beetle feeds on several species of agricultural plants as well as wild solanaceous plants. Their life cycle has been known in a certain species of plant, however none comparing both their life cycle and demography on different host plants. It has been well known that the species of insect responds physiologically different to the different of food plants. This research aimed to study the respons of H. vigintioctopunctata to the different of given food plants of S. torvum, S. nigrum, S. melongena, and Brugmansia suaveolens. Life cycle, demography, life table, and survivorship curve of the beetle were studied. Results showed that the longest time in life-cycle of H. vigintioctopunctata fed with S.nigrum (93,8 days, male and 104,1 days, female), respectively. The shortest time in life-cycle of H.vigintioctopunctata fed with S.melongena (16,5 days,male and 16,9 days, female), respectively. Highest number of eggs per egg mass occurred in H. vigintioctopunctata fed by S. nigrum (26,20 eggs per egg mass) and the lowest number occurred ini beetle fed by B. suaveolens (19,80 eggs per egg mass). Statistic demography of H.vigintioctopunctata showed that the highest value of gross reproductive rate was in S. torvum (5,5 individu) and the lowest value was in B. suaveolens (0,3 individu). The highest value of net reproductive Rrate was in S. torvum (2,11) and the lowest value was in B.suaveolens (0,02). The shortest of generation time was in S. melongena (5,9 days) and the longest of generation time was in S.nigrum (29,33 days). The higher value of intrinsic growth rate were in S.torvum (0,04) and S.nigrum (0,04), respectively and the lower value were in S. melongena (0,01) and B.suaveolens (0,01), respectively. Life-table analysis showed that the highest value of life expectation of egg and larval stages found on treatment with foliage of S. torvum. The highest value of mortality was found on S. nigrum (32,86%) and the lowest was found in S. melongena (16,67%). Based on value of its life-table, the most suitable host for development of H. vigintioctopunctata were S. torvum and S. nigrum. Survivorship curve of H. vigintioctopunctata showed that the highest number of mortality occurred in egg and larval stage.
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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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