BIO-ECOLOGY AND MANAGEMENT OF SCIRPOPHAGA FUSCIFLUA HAMPSON
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Date
2018-07-18
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CSKHPKV, Palampur
Abstract
Detailed studies on white stem borer, Scirpophaga fusciflua (Hampson) were undertaken at Rice and Wheat Research Centre of CSK Himachal Pradesh Krishi Vishvavidyalaya at Malan during Kharif season 2015-2017. The studies included white stem borer annual life cycle, its population build-up, assessment of yield losses inflicted and management with suitable insecticides and biopesticides. Three generations of white stem borer were recorded under laboratory conditions. Life history of white stem borer comprised of four well-defined stages viz., egg, larvae, pupa and adult. At the end of the crop season, as the temperature decreased, the full grown larvae diapaused in rice stubbles, adult of which emerged during last week of April to first week of May under laboratory conditions. The female moths on an average laid 58.4 to 65.6 eggs in masses in different generations with pre-oviposition, oviposition and post-oviposition period of 23.8 to 24.1, 24.9 to 26.0 and 6.0 to 6.6 hours, respectively. The larva passed through five instars to complete the larval development and the head capsule width increased with each instar. Population build-up of S. fusciflua was undertaken at three locations viz., Kohala, Jia and Malan. The pest appearance initiated during the month of July and the peak activity of pest was recorded during the month of August and September. The adult population had a positive relationship with minimum and maximum temperature and relative humidity whereas, rainfall influenced adult population negatively. However, the larval population was found to be negatively correlated with minimum temperature, rainfall, relative humidity (morning and evening). The plant infestation was found to have significant negative correlation with temperature (maximum and minimum), relative humidity (morning and evening) and rainfall. Stepwise regression analysis based on the data clubbed for three cropping seasons (2015-2017) revealed that minimum temperature, maximum temperature and rainfall influenced light trap and sweep net catch, significantly. Predators viz., spiders, dragonflies and damselflies, were found associated with white stem borer in paddy ecosystem. Four species of parasitoids viz., Telenomus sp. Tetrastichus sp. Stenobracon sp. and Xanthopimpla punctata were found to be associated with white stem borer. The plant infestation and losses inflicted to paddy due to different release levels of S. fusciflua viz., 2, 4 and 6 larvae per hill released at tillering stage revealed that maximum infestation in terms of dead hearts and white ears was 11.6 per cent at highest release level (6 larvae per hill) and lowest (6.2%) at release level of 2 larvae per hill and per cent avoidable losses varied from 7.5 to 32.3 per cent. Application of various insecticides viz., flubendiamide 48% SC @ 50 ml ha-1, rynaxypyr 20 SC @ 150 ml ha-1, dinotefuran 20 SG @ 200 g ha-1, monocrotophos 36 SL @ 850 ml ha-1 and two biopesticides viz., melia and eupatorium 5% extract @ 2.5 L ha-1 proved promising in checking white stem borer infestation, with flubendiamide being the most effective and more or less comparable with other insecticides. Among biopesticides, eupatorium application provided a significant check. However, maximum returns were obtained from monocrotophos and flubendiamide.
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