BIOLOGY AND MANAGEMENT OF BEAN APHID, APHIS CRACCIVORA (KOCH) ON MUNG CROP
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Date
2000
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Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu
Abstract
The investigation on the "Biology and management of bean aphid, Aphis craccivora (Koch) on mung crop" was conducted during kharif, 1999 at RARS, R.S.Pura and Pulses Research Sub-Station, Samba, SKUAST, Jammu. The female laid 32.15 + 6.38, 15.25 + 4.65, 38.25 ± 9.09 and 63.60 ± 7.08 nymphs in her life span during July, August, September and October with average temperature of 29.28 ± 3.04, 30.80 ± 2.87, 29.12 ± 3.31 and 25.33 ± 5.46°C and relative humidity was 79.61 + 12.02, 71.00 ± 12.94 , 72.60 ± 14.79 and 58.22 ± 20.79 per cent respectively. Whereas, the average fecundity per female per day was 5.08 ± 6.42, 3.08 ± 1.84, 5.52 ± 10.19 and 6.75 ± 5.87 nymphs at the corresponding temperature and relative humidity. The newly born nymphs passed through four instars. The 1st, 2nd, 3rd and 4th instar occupied a period of 1.55 ± 0.47,1.43 + 0.36,1.23 ± 0.19 and 1.37 + 0.34 days during July; 1.64 ± 0.42,1.42 ± 0.35,1.24 ± 0.31 and 1.36 ± 0.24 days during August and 1.38 + 0.34, 1.22 ± 0.24,1.09 ± 0.29 and 1.24 ± 0.37 days during September respectively. The mean nymphal period was 5.58 ± 0.81, 5.66 + 0.58 and 4.93 ± 0.41 days during July, August and September respectively. The adult longevity was 6.23 ± 1.85, 6.42 ± 1.76 and 6.87 ± 2.18 days and life span was 11.81 + 1.87, 12.08 ± 2.19 and 11.80 ± 1.78 days during the corresponding months with average temperature of 30.7, 29.7 and 26.2°C and relative humidity of 69.42, 76.57 and 62.35 per cent respectively. The morphometries (length x breadth) of 1st, 2nd, 3rd and 4th instar nymphs and adult female were (0.66 ± 0.05) x (0.32 ± 0.02), (0.90 ± 0.08) x (0.45 ± 0.05), (1.19 ± 0.11) X (0.62 ± 0.05), (1.42 ± 0.10) x (0.78 ± 0.08) and (1.74 ± 0.13) x (0.93 ± 0.09) mm respectively. The antennal length for corresponding instars and adult female was 0.37 ± 0.02, 0.57 ± 0.02, 0.68 ± 0.02, 0.79 ± 0.03 and 1.28 ± 0.02 mm respectivley. Twenty three mung genotypes were screened on the basis of aphid population in the terminal shoot and a foliar damage index (FDI). The aphid population ranged from 64.0 - 234.0 per 2.5 cm shoot length and FDI ranged from 0.6 - 3.5 per plant. Out of 23 mung entries, genotypes designated as resistant, moderately resistant, intermediate, susceptible and highly susceptible numbered 4, 5,5, 5 and 4 respectively. Five insecticides viz., endosulfan 35 EC, fenvalerate 20 EC, oxydemeton methyl 25 EC, cypermethrin 10 EC and malathion 50 EC each at three concentrations evaluated against the pest and were found superior to control. However, fenvalerate 0.03 per cent and cypermethrin 0.03 per cent proved most effective, whereas, endosulfan 0.05 per cent was least effective. The highest cost/benefit ratio (1:7.65) was obtained with fenvalerate 0.01 per cent followed by fenvalerate 0.02 per cent (1:5.87) and fenvalerate 0.03 percent (1:4.95).
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