Komposisi Spesies Penggerek Batang Padi dan Parasitoid Telurnya pada Ketinggian Tempat yang Berbeda

Composition of Rice Stem Borer Species and Their Egg Parasitoids at Different Altitudes. Rice stem borer is one of the main pest of rice plants that always percolating and attack plants in the field. The pests can result in damage to plants and lost of the grain from season to season. The aim of this research is to know composition and dominance rice stem borer species and role of their eggs parasitoid at an altitude of different places. Research is done by survey based on the height of different altitude in rice plants two weeks after cropping up until eleven weeks after planting. Research conducted from April until August 2019 in rice field that belonging to farmers at Subak Cemagi Let, Cemagi Village and Subak Teba, Mengwi village, Badung regency, Bali province. Subak Cemagi Let are at an altitude of 15 meters above sea level whereas Subak Teba are at an altitude of 300 meters above sea level. Identification of Rice stem borer larvae and their eggs parasitoid done in Pest Laboratory, Agriculture Faculty of Udayana University. Found three species rice stem borer in the height 15 mdpl namely Scirpophaga incertulas; Sesamia inferens dan Chilo suppressalis, whereas in the height 300 mdpl found four species namely Scirpophaga incertulas, Sesamia inferens, Chilo suppressalis, dan Chilo polychrysus. S. incertulas was the most dominant at the two different altitude. Three species of eggs parasitoid that have role to suppress the development of rice stem borer at the different altitude namely Tetrastichus schoenobii, Telenomus rowani dan Trichogramma japonicum. T. schoenobii was the most dominant to suppress rice stem borer populations.

KEANEKARAGAMAN, DOMINASI, PERSEBARAN SPESIES PENGGEREK BATANG PADI DAN SERANGANNYA PADA BERBAGAI TIPOLOGI LAHAN DI PROVINSI JAMBI

Diversity, domination, and distribution of rice stem borer species and its damage in various land typologies in Jambi Province. The research was conducted to analyze the diversity, domination, species distribution of rice stem borers (RSB) and its damage on various land typologies in Jambi Province. The research was carried out using survey method, from December 2010 until June 2011. Samples of RSB were collected from tidal swamp in Tanjung Jabung Timur District, swampy area in Muaro Jambi District, rainfed lowland in Sarolangun District, irrigated lowland in Merangin District, and irrigated upland in Kerinci District and Sungai Penuh District. The results showed that there were five spesies of RSB found in Jambi Province. Scirpophaga incertulas Walker (yellow stem borer) was the most dominant of RSB, followed by Sesamia inferens Walker (pink stem borer), Chilo suppressalis Walker (striped stem borer), Chilo polychrysus Meyrick (dark-headed stem borer), and Scirpophaga innotata Walker (white stem borer). The distribution of S. incertulas, S. inferens, C. suppressalis and C. polychrysus were in all of rice field in Jambi Province, but that of S. innotata was limited over tidal swamp and rainfield lowland area. The RSB damage rate was lower than economic thereshold.

The control of rice stem-borers (Lepidoptera: Pyralidae) by insecticides applied to the roots of rice plants

Experiments were conducted in Bangladesh in April–July and July–December to study the effectiveness of three methods of insecticide application to three varieties of rice against the stem-borers Scirpophaga incertulas (Wlk.) and Chilo polychrysus (Meyr.). In April–July, seedlings of the varieties IR8 and Dacca-14 were uprooted when 22 days old and treated individually with 0·0375%, 0·075%, 0·15% or 0·3% diazinon (as Diazinon 60 EC), dicrotophos (as Bidrin 85 EC) or carbaryl (as Sevin 85 SP) or 0·3% γ-BHC dust for 12, followed by dipping for 12 h in fresh water and then transplantation. In July–December, the same treatments were applied by controlled irrigation to the seedbeds of the varieties IR8 and Dacca-25 and for 40 h when the seedlings were 24 days old. In another experiment in July–December, granular formulations of diazinon (as Diazinon 5G), dicrotophos (as Bidrin 5G) and Sevidol (a mixed formulation of carbaryl 8G plus γ-BHC 8G) were also applied to the transplanted field at an interval of 20 days. Insecticides applied to uprooted seedlings reduced borer populations more in the case of variety IR8 than in Dacca–14. Diazinon applied at 0·3% to the variety IR8 and Dacca–25 effectively reduced the borer population to 4–8 and 10·5%, respectively, for up to 41 days; γ-BHC applied to the seedbed did not show much response. Dicrotophos was not highly effective in controlling the borers. Granular formulations of Sevidol at 1–5, 2 and 2–5 kg a.i./ ha and diazinon at 2–5 kg a.i./ha controlled stem-borers more effectively in variety IR8 than in Dacca-25. Variety IR8 was found more susceptible to the stem-borers than Dacca-25 and Dacca-14.