Judul: Field Survey of Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) on Corn Plants at Regency of Bogor, Sukabumi, Cianjur, and Tangerang
Abstrak: Jagung (Zea mays L.) merupakan salah satu komoditas penting setelah beras sebagai sumber karbohidrat dan pakan ternak. Kendala dalam budidaya tanaman jagung salah satunya diakibatkan oleh serangan hama. Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae) merupakan salah satu hama penting pada pertanaman jagung. Sejak tahun 2019 serangga ini adalah spesies invasif di pertanaman jagung Indonesia. Penelitian ini bertujuan untuk mengetahui persebaran hama Spodoptera frugiperda di Kabupaten Bogor, Sukabumi, Cianjur, dan Tangerang. Survei dilakukan di beberapa lokasi pertanaman jagung dengan jumlah yang berbeda di setiap kabupatennya. Survei meliputi pengamatan dan wawancara kepada petani jagung secara langsung. Beberapa larva dari tanaman yang terserang diambil dan diamati sampai fase pupa untuk mengetahui keberadaan patogen atau parasitoid yang berpotensi sebagai musuh alami di lapang. Serangan hama S. frugiperda terjadi pada tanaman jagung di beberapa lokasi di Kabupaten Bogor yang meyerang tanaman jagung, seperti Desa Cibeber dengan luas serangan mencapai 14.5% dan 17.3% di Desa Cisalada. Luas serangan di Desa Cimapak, Kabupaten Sukabumi 16.6% dan 14.3% di Desa Mekarsari, Kabupaten Tangerang. Serangan S. frugiperda tidak dilaporkan terjadi di Kabupaten Cianjur. Tanaman jagung yang diserang adalah pada bagian titik tumbuh (pucuk tanaman), bunga jagung, daun jagung, dan juga menyerang tongkol jagung. Ditemukan beberapa patogen yang belum diidentifikasi yang berasosiasi dengan S. frugiperda yang dipelihara. Kata kunci: Hama baru, persebaran hama, survei, tanaman jagung., Corn (Zea mays L.) is one of the important commodities after rice as a source of carbohydrate and animal feed. The one of obstacles in the corn cultivation is insect pests. One of the importants insect pests of corn is fall armyworm, Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae). The insect is invasive species on corn plantations in Indonesia since 2019. The aim of this research was to determine distribution of fall armyworm in corn plantation at area of Bogor, Sukabumi, Cianjur, and Tangerang. Survey was conducted in several locations of the corn plantations with different number of location site for each area. The survey includes direct observations of the insect damage and interviews with several corn farmers. Some larvae from the infested plants were collected and it was reared until pupa stage to determine presence of its natural enemies including pathogens or parasitoids that have a potential as natural enemies in the field. The survey result showed that demage of fall armyworm occurred in several corn field locations at Bogor Regency, such as in Cibeber Village with attack area of 14.5% and 17.3% in Cisalada Village; 14.7% of corn field in Cimapak Village, Sukabumi Regency, and 14.3% in Mekarsari Village, Tangerang Regency are reported damaged by this insect. However, there were no evidence that fall armyworm demage occurred at Cianjur Regency during the survey. The part of corn plants that were attacked by fall armyworm were at the growing point (palan shoots), corn flowers, corn leaves, and also attacked the corn cobs. There were unidentified natural enemies associated with the reared insects. Keywords: Corn plantation, new pest, pest attack, pest distribution, survey.
Keyword: Hama baru, Persebaran hama, Survei, Tanaman jagung

Judul: Infestation of Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) on Maize Plantations in Morotai Island, North Moluccas
Abstrak: Ulat gerayak jagung Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) merupakan hama invasif yang berasal dari Benua Amerika. Pada tahun 2019, S. frugiperda dilaporkan telah menyerang pertanaman jagung di Indonesia tepatnya di Kabupaten Pasaman Barat, Sumatra Barat dengan tingkat serangan berat. Persebaran hama ini semakin meluas ke berbagai wilayah di Indonesia termasuk ke wilayah Pulau Morotai, Maluku Utara. Penelitian ini bertujuan mengetahui jalur masuk, luas serangan, dan intensitas serangan S. frugiperda pada pertanaman jagung di Pulau Morotai, Maluku Utara serta merekomendasikan tindakan pengendalian. Penelitian dilaksanakan pada bulan Agustus hingga Desember 2020. Pengamatan dilaksanakan di dua lokasi yaitu di pertanaman jagung konvensional Desa Sambiki Baru dan di pertanaman jagung organik Desa Dehegila. Pengamatan luas dan intensitas serangan dilakukan setiap minggu pada umur tanaman 2 MST hingga 9 MST. Ulat gerayak jagung S. frugiperda terbawa tongkol jagung masuk ke Pulau Morotai melalui kapal dari Halmahera Utara. Luas serangan pada tanaman jagung konvensional tertinggi sebesar 78,14%, sedangkan pada jagung organik tertinggi sebesar 40,98%. Intensitas serangan pada tanaman jagung konvensional tertinggi sebesar 48,98%, sedangkan pada jagung organik tertinggi sebesar 31,6%. Tindakan pengendalian yang baik dapat dilakukan dengan penggunaan insektisida yang tepat sasaran dengan kombinasi strategi pengendalian lainnya., Fall armyworm Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) is an invasive pest native to the Americas. In 2019, S. frugiperda was reported to have attacked maize crops in Indonesia, precisely in West Pasaman Regency, West Sumatra with a heavy attack rate. The spread of this pest is increasingly widespread in various regions in Indonesia, including the Morotai Island region, North Moluccas. This study aims to provide information about port of entry, attack area, and intensity of S. frugiperda in maize on Morotai Island, North Moluccas and recommends pest management. The research was conducted from August to December 2020. The observations were carried out in two locations, namely in the conventional corn plantation in Sambiki Baru Village and in the organic maize plantation in Dehegila Village. Observation of the area of attack and intensity carried out every week starting when the maize plants were 2 WAP to 9 WAP. Fall armyworm S. frugiperda was carried with the corn cobs into Morotai Island via boat from North Halmahera. The highest attack area on conventional maize was 78,14%, while the highest for organic corn was 40,98%. The highest attack intensity on conventional maize was 48,98%, while the highest was 31,6% for organic corn. Pest management can be taken with targeted insecticides in combination with other control measures.
Keyword: fall armyworm, first report, port of entry

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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