Judul: Kelimpahan Wereng Batang Cokelat Nilaparvata lugens (Stål) dan Walang Sangit Leptocorisa oratorius (Fabricius) serta Predatornya pada Tanaman Padi Varietas IR 64
Abstrak: Permintaan masyarakat yang tinggi terhadap beras merupakan landasan untuk meningkatkan produksi beras nasional. Padi ‘IR 64’ memiliki potensi hasil yang cukup tinggi dan banyak ditanam petani di Indonesia. Ada dua hama penting pada pertanaman padi, yaitu wereng batang cokelat Nilaparvata lugens (Stål) (WBC) dan walang sangit Leptocorisa oratorius (Fabricius). Predator merupakan musuh alami yang paling berperan dalam menjaga populasi hama tetap pada batas keseimbangan. Penelitian ini bertujuan untuk memperoleh informasi kelimpahan WBC, walang sangit, serta predatornya pada tanaman padi ‘IR 64’. Pengamatan dilakukan pada pertanaman padi ‘IR 64’ seluas 400 m2. Pengamatan dilakukan secara langsung dengan menghitung populasi nimfa dan imago WBC dan walang sangit, serta kelimpahan predator. Pengamatan dilakukan mulai umur tanaman 1 minggu setelah tanam (MST) sampai 12 MST dengan interval 1 minggu. Hasil penelitian menunjukkan bahwa pada pertanaman padi IR 64, wereng batang cokelat ditemukan pada 1 MST dan mencapai puncak populasinya pada 10 MST. Walang sangit ditemukan pada 5 MST dan mencapai puncaknya pada 9 MST. Predator dominan yang ditemukan dari kelompok serangga adalah Cyrtorhinus lividipennis, Paederus fuscipes, Ophionea nigrofasciata, dan kumbang Coccinellidae. Sedangkan predator dari kelompok laba-laba yaitu famili Lycosidae, Oxyopidae, Linyphiidae, Tetragnathidae, dan Araneidae. Secara keseluruhan, perlakuan insektisida berbahan aktif imidakloprid terhadap WBC dan walang sangit tidak menunjukkan pengaruh yang berbeda nyata. Aplikasi insektisida pada 8 MST dan 10 MST berpengaruh terhadap penururan kelimpahan predator.
Keyword: kelimpahan, wereng batang cokelat, IR 64, walang sangit

Judul: Perkembangan Populasi Wereng Batang Cokelat Nilaparvata lugens (Stål) dan Musuh Alaminya pada Pertanaman Padi IPB 3S di Situgede, Bogor.
Abstrak: Padi merupakan salah satu sumber pangan utama bagi penduduk Indonesia. Padi ‘IPB 3S’ adalah padi varietas unggul yang mulai banyak ditanam petani. Wereng batang cokelat (WBC), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) merupakan salah satu hama penting pada pertanaman padi yang dapat menyebabkan kerusakan secara langsung maupun tidak langsung. Tujuan dari penelitian ini adalah mengetahui perkembangan populasi WBC dan musuh alaminya pada pertanaman padi ‘IPB 3S’ di Situgede, Bogor. Pengamatan dilakukan mulai umur tanaman 1 minggu setelah tanam (MST) sampai 12 MST dengan menggunakan metode pengamatan langsung. Hasil penelitian menunjukkan bahwa infestasi imago WBC makroptera dimulai pada umur tanaman 2 MST. Perkembangan populasi WBC mengalami dua kali puncak populasi yaitu pada umur tanaman 6 MST dan 10 MST. Musuh alami yang banyak ditemukan pada pertanaman padi ‘IPB 3S’ adalah laba-laba Pardosa sp., Paederus sp., Cyrtorhinus lividipennis, Ophionea sp. dan kumbang Coccinellidae. Secara umum, populasi WBC pada lahan tanpa perlakuan insektisida sama dengan lahan yang disemprot insektisida. Kelimpahan musuh alami pada lahan tanpa perlakuan insektisida lebih tinggi dibandingkan lahan yang disemprot insektisida.
Keyword: padi IPB 3S, populasi, musuh alami, wereng batang cokelat

Judul: The Effects of Variance of Interest rate to Variance of Annuity Future Values
Abstrak: Time value of money is a concept that refers to the difference of the value of money due to time difference. The value of money for present time would not be the same as the value of money in the future. The value of money for present time is called as Present Value (PV) of the money and the value of money for future time is called Future Value (FV) of the money. Determination the value of money, for present and future time, depends on the time and rate of return. The value of money is determined by several factors such as inflation, fluctuation of interest rates, and government policy in securities and taxation. Due to fluctuation of the value of money we need a FV formulation, it is useful for knowing whether an investment can be profitable or not, and this information is useful also in budget analysis. Annuity is defined as a series of payments made for a specific period. The payment, fixed or varied, can be made at the beginning or at the end of the period. Annuity paid at the beginning of the period is called annuity-due and annuity paid at the end of the period is called immediate annuity-certain. The accumulated value of the annuity after few years later is called as a final value or a future value. Burnecki et al. (2003) have discussed about the FV of a fixed-rate annuity in which payments are made according to the arithmetic or geometric series. They have also examined FV for annuities in which payments are made according to arithmetic or geometric series with random rates of interest. This paper examines FV for annuity-due in which payments are made according to arithmetic or geometric series with interest rates as a random variable, which is normal distribution ,  . Future value formula is expressed in recursive form. FV for annuity-due which payments are made according to the arithmetic or geometric series with random rates of interest is calculated by theoretical way and simulation way. The random rates of interest is denoted as k k i  i  , where k i an independent random variable; i is a constant and k  is a random variable which has normal distribution ,  . By using the determined parameters, a sequence of random rates of interest are generated for theoretical calculation. Meanwhile for the simulation, the random rates of interest is generated 1000 times for the simulation. The generated data give mean value, variance, and standard deviation. Moreover, error of mean value, variance, and standard deviation from the theoretical and simulation results are calculated. Error calculation uses Symmetric Mean Absolute Percentage Error (SMAPE). The smaller the value of SMAPE is the more accurate the simulation. The interest rate variances are varied from 0.000036 to 0.0001 to study the relationship between variance of rates of interest and variance of future value. The theoretical and simulation results show that when the variance of random rates of interest increases, then the variance of FV increases linearly. FV of the annuity-due in
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