STUDIES ON INSECT PEST COMPLEX OF GROUNDNUT (Arachis hypogaea L.) WITH SPECIAL REFERENCE TO EMERGING PEST, Maruca vitrata (Geyer) (Lepidoptera: Pyralidae) DURING rabi SEASON
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Date
2016
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Acharya N.G. Ranga Agricultural University, Guntur
Abstract
The present investigation on “Studies on insect pest complex of groundnut (Arachis hypogaea L.) with special reference to emerging pest, Maruca vitrata (Geyer) (Lepidoptera: Pyralidae) during rabi season” was carried out in Department of Entomology, S. V. Agricultural College, Tirupati. The Experiment was conducted during rabi, 2015-2016.
Afield experiment was laid out to study insect pest incidence in groundnut varieties (Dharani and K-6) with special reference to M. vitrata at 4 dates of sowing Nov II FN, Dec I FN, Dec II FN and Jan I FN during rabi 2015-16. Result indicated that M. vitrata incidence was high in D1 and D2scown crop where as it was totally absent in D3 and D4 sown groundnut. Between the two varieties i.e. infestation observed in Dharani and K-6 was ranged from 0.89 to 17.25 and 0.66 to 13.78 per cent respectively. The damage was comparatively high on Dharani as it was ranged from 7.60 to 17.25 per cent during 3rd to 9th standard weeks. Similarly incidence of S. litura recorded more infestation in D1 and D2 sown crop and it was ranged from 0.32 to 20.22 and 0.2 to 28.14 per cent in Dharani and K-6. Comparatively infestation was more in K-6 and it was ranged from 12.82 to 28.14 during the 50th standard week of 2015 to 6th standard week of 2016. Incidence of leaf miner was more in D3 and D4 sown crop compared with D1 and D2 sown crop and it was
ranged from 15.54 to 38.46 and 15.48 to 41.59 in Dharani ad K-6 varieties respectively. Thrips damage was more in all the dates of sowings and the infestation ranged from 0.34 to 29.47 and 0.63 to 28.45 in Dharani and K-6 respectively, infestation was high during the 4th to 15th standard week. There is no much difference between two varieties with respect to thrips damage.
Survey on M. vitrata incidence in groundnut was conducted during rabi 2015-16 in eastern parts of Chittoor and Nellore districts. The result revealed that there was not much variation in M. vitrata incidence levels in the surveyed areas of both Chittoor and Nellore districts i.e. 11.12 ± 1.56 and 11.82 ± 1.49 respectively. Four groundnut cultivars were majorly grown in the two districts Chittoor and Nellore districts i.e.. mainly Dharani, K-6, TAG-24 and JL- 24. Out of these Dharani occupied 40-55 per cent , K-6 30-35 per cent, TAG-24 5-20 per cent and JL-24 5 to 10 per cent in Chittoor and Nellore districts. From the survey data it was found that majority of the farmers preferred insecticide chlorpyriphos which ranged from 40 to 45 per cent followed by novaluron + indoxacarb from 15 to 20 per cent, emamectin benzoate 10 to 15 per cent, novaluron 10 to 15 per cent and quinalphos 5 to 10 per cent for spraying against M. vitrata infestation in Chittoor and Nellore districts, respectively.
A screening trial was laid out with twenty one genotypes and four checks of groundnut for their reaction against the spotted pod borer (M.vitrata) in the dryland farm of S.V. Agricultural College, Tirupati during rabi, 2015-2016. The results revealed that the genotypes viz., ICGV-86368, K-9, TAGS-1426 and CS-19 have showed less infestation of M. vitrata. The genotypes viz., Dharani, Kadiri-6 (K-6), Narayani and TCGS-1543 have recorded high per cent of infestation. Infestation of M. vitrata on groundnut positively correlated with (r = 0.43) with specific leaf area and negatively correlated (r = -0.48) with SPAD Chlorophyll meter readings at 60 DAS.
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D5336
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