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: Kapasitas Konsumsi Larva dan Imago Epilachna vigintioctopunctata (Fab.) (Coleoptera: Coccinellidae) pada Inang Terung (Solanum melongena) dan Tomat (Lycopersicum esculentum).
Abstrak: The hadda beetle of Epilachna vigintioctopunctata is an important pest on Solanaceae plants. Crops devoliation are strongly influenced by food consumption pattern on each host plant. The aim of this study is to compare the consumption of E. vigintioctopunctata on eggplant and tomato leaves and its influenced on the acceleration of larval growth rate, the body size, the length of each instars periods, and standing position of the beetles during eating. Each tested leaf was taken from two-month-old host plants and fed to newly hatched instars larvae. The daily leaf areal consumed and the body lengths of insect were measured until the adult died. The changing of instars morph and the position of insect on the leaf surface were also observed. The average rate of food consumption by fourth instar larvae and adult were significantly higher on eggplants 190.5 and 190.8 mm2/days compared with tomatoes 76.40 and 127.1 mm2/days, respectively. The total areas of damaging leaf within 17.2 days during larval and adult feeding stage were 2069.1 mm2/insect on eggplants and 1067.3 mm2/insect on tomatoes. Food consumption on the eggplant shortened the length of the pupal period and increased the longevity of adult to become 4 and 9 days, respectively. Highly food consumption by the third instar larvae almost produced the same size of the next fourth instar, further consumption caused the lengthened of pupal size and the shortened of adult on the eggplant compared with tomato. The growth rate of larval body size was 0.5-0.7 mm/day on eggplants significantly higher than tomatoes was 0.1-0.3 mm/day. The adult beetles tend to stay on the upper surface, while the larvae prefer on the lower surface of both eggplant and tomato leaves. In general, E. vigintioctopunctata devastated more on the eggplant than tomato leaves.
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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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