Judul: Biologi dan Potensi Peningkatan Populasi Kutu Putih Singkong, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), Hama Pendatang Baru di Indonesia
Abstrak: The cassava mealybug, Phenacoccus manihoti Matile-Ferrero (Hemiptera: Pseudococcidae), has been reported as a new invasive pest causing heavy damage on cassava in Indonesia since 2010. Study was conducted in laboratory with the objectives to determine the biology and life table parameters of the mealybug as feeding on cassava plants. P. manihoti is parthenogenic species, producing only female offspring. The eggs hatched 7-8 days after oviposition. Nymphal instar-1, - 2, -3 lasted 4.58, 4.20, 4.58 days, respectively. Adult female mean longevity was 34.38 days, with an average fecundity was 570 eggs. The intrinsic rate of increase (rm) was 0.213 female offspring per female per day. The mean generation time (T) was 28.48 days and the net reproductive rate (Ro) during this period was 456.02. The finite rate of increase (λ) was 1.24 times per days and the population doubling time (Dt) was 3.22 days.
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Judul: Biologi perkembangan dan neraca hayati kutu putih pepaya, Paracoccus marginatus (Williams and Granara de Willink) (Hemiptera: Pseudococcidae) pada tiga jenis tumbuhan inang
Abstrak: The papaya mealybug, Paracoccus marginatus Williams & Granara de Willink (Hemiptera: Pseudococcidae), has been considered as a new invasive pest causing heavy damage on papaya in Indonesia since 2008. The pest is polyphagous with more than 55 host plant species. Study was conducted in laboratory with the objectives to determine developmental biology and life table parameters of the mealybug feeding on papaya, physic nut, and cassava leaves. Host plant species affected papaya mealybug performances. Egg stage lasted 7,25, 8,09, and 9,86 d on papaya, physic nut, and cassava, respectively. The shortest female nymphal developmental time was on papaya (18,91 d) and the longest on cassava (32,45 d). Longevity of adult males ranged from 1,09-2,85 d while females 12,29-14,93 d, respectively. When the mealybugs were reared on a seedling, the fecundity was higher on papaya (324,6) than those of physic nut (186,6) and cassava (157,5). No egg production occurred in virgin females. The sex ratio of P. marginatus favoured females, which comprised about 90% of population on papaya and cassava. The intrinsic rate of increase (rm) was significantly different among hosts, with the highest rate (0,117 female offspring/female/d) occured on papaya, followed by physic nut (0,079) and cassava (0,057). The maximum values of rm along with net reproductive rate (Ro) and finite rate of increase (λ), and the shortest mean generation time (T) and doubling time (DT) on papaya, indicating that papaya was the most favorable host plant for P. marginatus.
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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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