SEASONAL INCIDENCE AND MANAGEMENT OF RICE STEM BORERS (SCIRPOPHAGA SPP.) ON RICE (ORYZA SATIVA L.)
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Date
2017
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Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu
Abstract
Study on Seasonal incidence and management of rice stem borers (Scirpophaga spp.) on rice (Oryza sativa L.) was carried out at Plant Pathology field, Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu, Chatha during Kharif 2015. The observations on natural infestation of rice stem borers, Scirpophaga spp. on rice were recorded at weekly intervals starting from 27th SW to 46th SW during kharif 2015. The seasonal incidence of rice stem borers observed at experimental sites indicated that Yellow stem borer (YSB), Scirpophaga incertulus and white stem borer (WSB), S. innotata were found damaging and remain active on the crop during vegetative and reproductive stages of crop growth. Besides the insect pests, natural enemy fauna were also abundantly found in rice agro-ecosystem. The study revealed that different types of dragonfly, damselfly, coccinellids, spiders, robber fly, ground beetles were actively noticed in rice crops predating upon the stem borer adults population. Apart from predatory fauna, some parasitoids were also observed such as Xanthopimpla spp. Tetrastichus parasitoid, Teleonomus spp. on egg mass of rice stem borers. During kharif 2015, mean number of Yellow stem borer (YSB) population on rice was observed to be increasing gradually till 38th SW recording a maximum of 11.33 larvae / 10 hills. While in case of white stem borer (WSB), S. innotata, the seasonal incidence of larval population was ranged from 1.0 to 14.67 larvae / 10 hills. The population WSB was observed to be peak larval number in 32nd SW with 11.00 larvae / 10 hills and 14.67 larvae / 10 hills during 38th SW. Thus, there was two peak of WSB larval population build-up observed during 32nd and 38th standard weeks on rice crop during 2015. The relationship between abiotic factors and incidence of YSB and WSB larval population when worked out during 2015, it was observed that YSB and WSB larval populations was found significantly correlated with morning relative humidity and rainfall, respectively. The maximum percentage damage of dead heart was noticed in 38th SW and remains observed just before the maturity of rice crop whereas, white ear was recorded on 35th SW with 2.92 per cent during kharif 2015. A weekly interval survey on white ear percentage due to stem borer revealed that the mean white ears were ranged from 2.92 to 14.58. The relationship between abiotic factors and percentage of dead hearts and white ears were found significantly correlated with morning relative humidity and rainfall, respectively. The overall impact of weather factors on the white ears was 74.10 per cent. The maximum catches were recorded in 38th SW with 20.33, 27.33 and 14.67 adults population in light and pheromone traps, respectively. The perusal of data showed that more number of YSB adults was caught in light trap than the pheromone trap. The adult population fluctuated between 32nd to 38th standard weeks, exhibiting one āVā shaped oscillations. Thus, there were two peaks of YSB adult trap catch population noticed during 33rd standard week (13.67) and 38th SW in light trap and 32nd SW (11.00) and 38th SW in pheromone traps, respectively. White stem borer (WSB) adults catches also showed the two peaks viz., in 32nd SW (19.33) and in 38th SW in light traps. The relationship between abiotic factors and rice stem borers (RSB) male adult population by light trap and YSB through pheromone trap catches showed that only pheromone trap catches of YSB was found significantly correlated with morning relative humidity and rainfall, respectively. After 15th days of 1st spray, spinosad was found to be the best treatment in reducing the stem borer population on rice followed by novaluron (72.57 per cent) and cartap hydrochloride (62.38. per cent). In these results, spinosad is the most effective up to 15th days and significantly different from other treatments at 5 per cent level of significance. Overall, spinosad and cartap hydrochloride were the most effective treatment after two sprays up to 15th days in reducing the stem bore population and found to be significantly different from other treatments at 5 per cent level of significance. The descending order of performance of different treatments were found as follows- Spinosad> cartap hydrochloride> Thiodicarb> imidacloprid> Buprofezin + acephate> Bacillus thuringiensis> Novaluron> Azadirachtin.
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