Judul: Impact of Rice Straw Incorporation and Insecticide Application on Insect and Spider Biodiversity and  Brown Planthopper Populations
Abstrak: Biodiversity in agricultural ecosystems plays a crucial role in maintaining ecological balance and supporting increased food crop production. In Indonesia, especially in rice cultivation, there is a tendency to make agroecosystems fragile, thereby increasing the potential for the explosion of pest populations, such as the brown planthopper (BPH). One potential solution to enhance the health of rice plants is to return straw after harvest to agricultural fields. This step contributes to maintaining the balance of paddy ecosystems and improving crop production. Optimizing straw incorporation can be enhanced by judiciously applying appropriate and wise insecticides. Therefore, this study aims to investigate the effects of returning organic material, namely rice straw, and applying insecticides with different spectrums and selectivities to rice cultivation. The impacts are observed on soil nutrient content, microbial activity, plant growth, insect and spider diversity, the dynamics of the main pest, BPH population and their effects on yield. Observations of the interaction between straw incorporation and insecticide application were made during two different planting seasons in the experimental field of PT Corteva Agriscience Indonesia, located in Ciwaringin Village, Lemahabang, Karawang Regency, West Java, from January to September 2022. The research design utilized a split-plot design, with two main plots (with and without straw incorporation) and three subplots (without insecticide, broad-spectrum fipronil insecticide, and narrow-spectrum triflumezopyrim insecticide. Soil nutrient and microbial samples were collected by taking soil samples from each plot after planting the land. Insect and spider samples were taken every two weeks using suction devices and insect nets, while BPH population observations were conducted every week until one week before harvest. The overall research results indicate that straw incorporation elicits a positive response regarding plant growth, insect and spider diversity, reduced pest insect populations, and increased natural enemy populations. However, the level of this positive response is influenced by the planting season. Conversely, applying narrow-spectrum insecticides is more effective in protecting rice plants from BPH infestation, positively impacting increased yields. In conclusion, the combination of straw incorporation and triflumezopyrim insecticide application is expected to provide better results for rice protection against BPH infestations., Keanekaragaman hayati dalam ekosistem pertanian memainkan peran penting dalam menjaga keseimbangan ekologi dan mendukung peningkatan produksi tanaman pangan. Di Indonesia, khususnya pada budi daya padi, ada kecenderungan membuat agroekosistem menjadi rapuh, sehingga meningkatkan potensi peledakan populasi hama seperti wereng batang cokelat (WBC). Salah satu solusi potensial untuk meningkatkan kesehatan tanaman padi adalah mengembalikan jerami sisa panen ke lahan pertanian. Langkah ini tidak hanya dapat menjaga keseimbangan ekosistem padi sawah secara tidak langsung, tetapi juga dapat meningkatkan produksi tanaman. Optimalisasi pengembalian jerami dapat ditingkatkan dengan penggunaan insektisida yang tepat dan bijaksana. Oleh karena itu, penelitian ini bertujuan untuk memahami pengaruh dari pengembalian bahan organik berupa jerami dan aplikasi insektisida dengan spektrum dan selektivitas yang berbeda pada pertanaman padi dengan mengamati pengaruhnya terhadap kandungan unsur hara dan mikroba tanah, pertumbuhan tanaman, keanekaragaman artropoda, dinamika populasi hama utama, yaitu WBC, hingga pengaruhnya terhadap hasil panen. Pengamatan interaksi antara pengembalian jerami dan aplikasi insektisida diamati pada dua musim tanam yang berbeda di lahan percobaan PT Corteva Agriscience Indonesia, Desa Ciwaringin, Lemahabang,
Keyword: agroecosystem, fipronil, organic material, triflumezopyrim

Judul: Population of Plant-hoppers and Spiders in Biointensive and Conventional Rice Croping
Abstrak: Padi merupakan salah satu tanaman serelia penting yang digunakan sebagai makanan pokok sebagian besar penduduk dunia. Padi tergolong dalam tanaman pangan berupa rumput berumpun dan memiliki kemampuan beradaptasi yang tinggi pada berbagai kondisi lingkungan. Penelitian bertujuan mengetahui perbandingan populasi hama wereng dan populasi laba-laba pada pertanaman padi biointensif dan konvensional di Kampung Darim, Kecamatan Terisi, Kabupaten Indramayu, Provinsi Jawa Barat. Metode penelitian yang digunakan adalah metode pengamatan langsung dilakukan dengan menetapkan titik pengamatan secara terpilih yang mewakili bagian tengah lahan sawah dengan ukuran 10 m x 10 m. Pada setiap lahan sawah ditentukan 100 grid pengamatan, grid pengamatan berukuran 1 m2. Data diolah dan dianalisis menggunakan aplikasi Microsoft excel 2013. Hasil penelitian menunjukkan bahwa populasi wereng lebih tinggi pada lahan pertanaman padi dengan perlakuan biointensif, populasi laba-laba lebih tinggi pada lahan pertanaman padi dengan perlakuan biointensif. Spesies yang ditemukan yaitu Araneus inustus, Neoscona theisi, Atypena adelina, Pardosa pseudoannulata, Tetragnathidae sp., Oxyopes javanus, dan Harmochirus sp. Dominasi spesies yang ditemukan yaitu Atypena adelina baik pada lahan dengan perlakuan biointensif maupun konvensional. Famili yang mendominasi pada pada lahan dengan perlakuan biointensif maupun konvensional adalah Famili Araneidae., Rice is one of the important cereal crops which is used as a staple food for most of the world's population. Rice is classified as a food crop in the form of clump grass and has high adaptability to various environmental conditions. This study aims to determine the comparison of planthopper populations and spider populations in biointensive and conventional rice plantations in Darim Village, Terisi District, Indramayu Regency, West Java Province. The research method used is a direct observation method carried out by determining selected observation points that represent the middle of the rice field with a size of 10 m x 10 m. In each rice field, 100 observation grids are determined, the observation grid is 1 m2 in size. The data was processed and analyzed using the Microsoft Excel 2013 application. The results showed that the planthopper population was higher on rice plantations with biointensive treatment, the spider population was higher on rice plantations with biointensive treatment. The species found were Araneus inustus, Neoscona theisi, Atypena adelina, Pardosa pseudoannulata, Tetragnathidae sp., Oxyopes javanus, and Harmochirus sp. The dominant species found was Atypena adelina both on land with biointensive and conventional treatment. The family that dominates on land with biointensive and conventional treatment is the Araneidae family.
Keyword: dominasi, keragaman, musuh alami

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
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