DINAMIKA POPULASI WERENG BATANG COKLAT Nilaparvata lugens Stal (HEMIPTERA: DELPHACIDAE) DAN PREDATOR GENERALIS PADA PERTANAMAN PADI PASCA PENERAPAN REKAYASA EKOSISTEM

Rekayasa ekologi melalui manipulasi habitat merupakan bentuk konservasi ekologi yang bertujuan melestarikan keberadaan musuh alami, salah satunya golongan predator generalis. Usaha ini merupakan strategi PHT untuk menangani masalah WBC (Nilaparvata lugens). Penelitian ini bertujuan untuk mengamati perkembangan populasi WBC dan predator generalis pasca penerapan rekayasa ekosistem. Penelitian dilakukan di lahan persawahan Desa Tejoasri, Laren, Lamongan dengan mengamati populasi WBC, predator umum, pertumbuhan dan perkembangan tanaman, dan analisis usahatani. Plot PHT berbasis rekayasa ekosistem (PHT-RE), PHT konvensional (PHT), dan budidaya konvensional digunakan untuk memperoleh data. Hasil rerata populasi WBC pada perlakuan PHT-RE (8,73 ekor) , berbeda sedikit dengan hasil plot PHT (8,55 ekor), namun hasil keduanya jauh lebih rendah dibandingkan dengan sistem konvensional (14,27 ekor). Predator generalis yang ditemukan pada saat pengamatan terdiri dari laba-laba, capung, kumbang kubah (Coccinelidae), kumbang botol (Ophionea indica), dan Paederus sp. Jenis predator spesialis juga ditemukan yaitu Cyrtorhinus lividipennis. Populasi predator generalis tertinggi ditemukan pada petak PHT-RE (1069 ekor), diikuti petak PHT (656 ekor) dan konvensional (426 ekor). Nilai BCR yang diperoleh pada perlakuan PHT-RE, PHT, dan konvensional berturut-turut yaitu 3,78, 3,25, dan 1,84.

The Amino Acid-Mediated TOR Pathway Regulates Reproductive Potential and Population Growth in Cyrtorhinus lividipennis Reuter (Hemiptera: Miridae)

The predatory mirid bug, Cyrtorhinus lividipennis Reuter, feeds on brown planthopper (BPH) eggs that are deposited on rice and gramineous plants surrounding rice fields. The development and reproduction of C. lividipennis are inhibited by feeding on BPH eggs from gramineous species, and the underlining regulatory mechanism for this phenomenon is unclear. In the present study, HPLC-MS/MS analysis revealed that the concentrations of six amino acids (AAs:Ala, Arg, Ser, Lys, Thr, and Pro) were significantly higher in rice than in five gramineous species. When C. lividipennis fed on gramineous plants with BPH eggs, expression of several genes in the target of rapamycin (TOR) pathway (Rheb, TOR, and S6K) were significantly lower than that in the insects fed on rice plants with BPH eggs. Treatment of C. lividipennis females with rapamycin, dsRheb, dsTOR, or dsS6K caused a decrease in Rheb, TOR, and S6K expression, and these effects were partially rescued by the juvenile hormone (JH) analog, methoprene. Dietary dsTOR treatment significantly influenced a number of physiological parameters and resulted in impaired predatory capacity, fecundity, and population growth. This study indicates that these six AAs play an important role in the mediated-TOR pathway, which in turn regulates vitellogenin (Vg) synthesis, reproduction, and population growth in C. lividipennis.