Judul: Kesesuaian Inang dan Perilaku Makan Kutudaun Pentalonia nigronervosa Coquerel dan Pentalonia caladii van der Goot (Hemiptera: Aphididae) pada Berbagai Kultivar Pisang
Abstrak: Banana aphids (Pentalonia nigronervosa Coquerel) and taro aphids (Pentalonia caladii van der Goot) have been reported as banana pests and known as vectors for Banana bunchy top virus (BBTV). Host suitability and feeding behavior of P. nigronervosa and P. caladii will influence their potential to transmit BBTV. This study aimed to determine the most suitable banana cultivars for banana and taro aphids and to analyze the feeding behavior of banana and taro aphids using an electrical penetration graph (EPG). The experiments were conducted using a completely randomized design with aphid species (P. nigronervosa and P. caladii) and banana cultivars (‘Mas Kirana’, ‘Klutuk’, ‘Barangan Jumbo Merah’, ‘Ambon Kuning’, ‘Tanduk’, and ‘Kepok Kuning’) as the treatments. Each treatment was replicated three times, and each replication consisted of 12 plants. The host suitability test was conducted in the greenhouse. Five adult aphids were infested on each banana cultivar, then observation of aphid population was done every day for 30 days. Feeding behavior of aphids with EPG were conducted in the laboratory and observations of aphid feeding behavior were made every 10 hours. Based on the development of aphid population it is known that the most suitable banana cultivars for P. nigronervosa and P. caladii are ‘Barangan Jumbo Merah’ and ‘Ambon Kuning’, meanwhile unsuitable banana cultivars are ‘Klutuk’ and ‘Kepok Kuning’. The highest feeding activity of P. nigronervosa was observed on three banana cultivars, i.e. ‘Mas Kirana’, ‘Barangan Jumbo Merah’, and ‘Ambon Kuning’; while P. caladii only on two cultivars, i.e. ‘Barangan Jumbo Merah’, and ‘Ambon Kuning’. P. nigronervosa and P. caladii exhibited low feeding activity on cv. Klutuk and cv. Kepok Kuning. The information on specific banana cultivars that support aphid population development is crucial for effective management of banana bunchy top disease.
Keyword: Aphid population, Banana bunchy top virus, EPG, insect vectors of plant disease

Judul: Aphids infesting bananas in Java: Identification, Morphometric, Host Range, and Population Density
Abstrak: Banana aphid, Pentalonia nigronervosa Coquerel (Hemiptera: Aphididae) has been known as the vector of Banana bunchy top virus (BBTV), the causal agent of banana bunchy top disease. The disease is threatening production of banana which can cause yield loss up to 100%. Understanding the basic information of the vector can help farmers and IPM practitioners to formulate better and more effective strategies in controlling the BBTV distribution. The goal of this research was to identify and to analyze morphometric characters of aphids infesting banana in Java, to determine the banana aphid host range and its population density. Sampling was done by using purposive method. Morphology and morphometry of aphid observation was conducted to identify aphids infesting banana and non banana host plants. As many as 151 specimens collected from various of banana cultivars were examined to identify the species of aphid infesting banana in Java. Moreover, as many as 101 specimens was selected from eleven banana cultivars of West Java, Central Java and East Java in order to assess the morphometric variation of P. nigronervosa. Morphological measurement was derived from image-measuring using Stereo Microscope Leica M 205C and Leica Application Suit Software Version 4.4.0. Eleven morphometric characters of apterous (wingless aphid) were measured: length of body, head width, antennal length, length of antennal segment I-II, length of antennal segment III-V, length of antennal segment VI, length of ultimate rostrum segment, length of siphunculus, length of femur, length of tibia and length of caudal. Investigation of population density of banana aphids was conducted on two different altitudes, i.e. <500 m asl and 500-1000 m asl. The observation was done on a total of 320 banana suckers from 32 villages in West Java, Central Java and East Java. Suckers with 50-150 cm height were selected for aphid observation. Aphid species identification was done based on the identification key by Blackman and Eastop (2006) and Miller et al. (2014). The morphometric data was analyzed using Principle Component Analysis (PCA). Multivariate analysis of variance (MANOVA) was done to test the morphometric differences among the colonies of P. nigronervosa. Linear discriminant analysis (LDA) was performed to test the classification of the species based on the morphometric characters. Cluster analysis with unweighted pair group method with arithmetic mean (UPGMA) using Euclidian distance was conducted to assess character similarity of P. nigronervosa collected from different banana cultivars. The identification result showed there were two aphid species infesting bananas in Java, P. nigronervosa and P. caladii. P. nigronervosa mostly infested bananas (Musa spp.), and a few on heliconia (Heliconia sp.) and the banana traveler (Ravenala madagascariensis). In contrast P. caladii was rarely found on bananas; the aphid generally infested taro (Colocasia esculenta), turmeric (Curcuma longa), costus (Costus sp.), and dumbcane (Dieffenbachia sp.). Some new host plants of banana aphids in Java were recorded in this study, P. nigronervosa was found on banana traveler (Ravenala madagascariensis) and P. caladii was found on banana (Musa sp.), turmeric (Curcuma longa), and banana traveler (Ravenala madagascariensis). The morphometric variation of P. nigronervosa inhabiting different banana cultivars in Java was clearly indicated by the PCA
Keyword: Banana bunchy top virus, banana genome, morphology character, multivariate analysis, Pentalonia spp

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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