BIOECOLOGY AND MANAGEMENT OF RICE HISPA, DICLADISPA ARMIGERA (OLIVER) UNDER MID-HILL CONDITIONS OF HIMACHAL PRADESH
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Date
2017-04
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CSKHPKV, Palampur
Abstract
Detailed studies on rice hispa, Dicladispa armigera (Oliver) were undertaken at CSK Himachal Pradesh Krishi Vishvidyalaya, Rice and Wheat Research Centre, Malan during 2014-2016. The studies included understanding rice hispa’s annual life cycle, its population build-up, assessment of losses inflicted and management with suitable insecticides and biopesticides. The life history of D. armigera consisted of four distinct stages viz. egg, grub, pupa and adult, each having an average duration of 4.5, 14.0, 9.1 and 22.4 (male); 38.7 (female) days, respectively. Both adults and grubs caused damage due to its feeding on paddy leaves. As many as 3-4 generations were recorded under laboratory conditions (mid June-mid November), but the adults of last generation failed to lay eggs. A few individuals of adults of last generation survived on rice seedlings and weed host, Cynodon dactylon (Linn.) till April-May with limited feeding and no egg-laying. Field observations recorded the incidence of hispa adults on wheat crop during February-April. With the early monsoon showers, the adults of hispa started appearing on weeds viz. C. dactylon, Cyperus rotundus (Linn.), Andropogon gayanus (Kunth), Digitaria sanguinalis (Linn.) and Panicum dichotomiflorum Michx., etc in the early June and thereafter it started feeding on paddy crop as soon as it was transplanted (July). During early stages of crop till 39th Standard Meteorological Week (SMW), both adult and grub incidence were recorded on paddy, which built-up during the season. Adults remained associated with the crop till its maturity. The population reached its peak during 31-39 SMW (August-September). Relative humidity significantly and positively influenced its build-up. Natural parasitization of grubs (or pupae) by a eulophid wasp, Chrysonotomyia sp. was reported. Damage and losses inflicted to paddy due to rice hispa as quantified by release density and phenological crop stage revealed that release at early stage (20-days after transplanting, DAT) inflicted more leaf damage (64.9 per cent leaf damage index, at 3-hispa release density) compared to later stages. Moreover, the regression analysis revealed that per unit increase in hispa density at early stage (20-DAT) resulted in 5.82, 5.73, 441.4 reduced number of tillers, panicles and grains, respectively, and the respective grain weight by 8.06g (per four rice hills). Also, at release stage of 40-DAT, the grain number and grain weight reduced significantly (b= 258.5 and 6.87, respectively), but at advanced release stage (60-DAT), no significant losses were recorded. Application of various insecticides viz. dinotefuran 20 SG, triazophos 40 EC, chlorpyriphos 20 EC, monocrotophos 36 SL @ 200g, 500, 1250, 850 ml ha-1, respectively, and biopesticides viz. beauveria 106 spores ml-1, melia 5 per cent, eupatorium 5 per cent @ 5.0, 2.5, 2.5L ha-1, respectively, proved promising in checking hispa infestation, with dinotefuran being the most effective and more or less comparable with other insecticides. Among biopesticides, beauveria application provided a significant check. However, maximum returns were obtained from triazophos.
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