STUDIES ON SCREENING OF GERMPLASM, LARVAL TAXONOMY AND MANAGEMENT OF LEPIDOPTERAN PEST COMPLEX OF CASTOR

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Date
2024-03-20
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Acharya N G Ranga Agricultural University
Abstract
“Studies on screening of germplasm, larval taxonomy and management of lepidopteran pest complex of castor” were undertaken in the Department of Entomology, S.V. Agricultural College, Tirupati during rabi, 2021-22. Investigations on screening of germplasm against lepidopteran pest complex of castor viz., Spodoptera litura, Achaea janata, Ergolis merione and Conogethes punctiferalis with twenty three genotypes revealed that none of the genotypes were found resistant to lepidopteran pest complex. Based on the defoliation scale nine genotypes viz., GC-3 (9.86 % defoliation), ICS-164 (10.13 %), DCH-519 (10.48 %), YTP-1 (10.92 %), DCS-107 (11.78 %), DCS-8g (12.70 %), DCS-9 (12.72 %), 48-1 (13.63 %) and GC-2 (14.33 %) were categorised as tolerant. Three genotypes viz., Haritha (21.58 %), SKI-215 (23.81 %) and SKI-291 (24.07 %) were categorised as moderately tolerant. Based on the per cent capsule damage scale, none of the genotypes were categorised as resistant. six genotypes viz., ICS-164 (0.26 % capsule damage), SKI-215 (0.39 %), GC-3 (0.76 %), DCS-8g (2.57 %), DCS-9 (8.72 %) and 48-1 (8.25 %) were categorised as tolerant. Six genotypes viz., DCS-107 (12.32 %), YTP-1 (12.52 %), GC-2 (12.99 %), DCH-519 (15.65 %), Haritha (16.31 %) and SKI-291 (18.69 %) were categorised as moderately tolerant. The mean larval population of S. litura in different genotypes ranged from 0.31 to 2.23 larvae plant-1. The lowest larval population was observed in the genotypes viz., DCS-107 (0.31 larvae plant-1), GC-2 (0.34 larvae plant-1), DCH-519 (0.36 larvae plant-1), SKI-291 (0.39 larvae plant-1) DCS-9 (0.40 larvae plant-1), 48-1 (0.42 larvae plant-1), YTP-1 (0.46 larvae plant-1), GC-3 (0.51 larvae plant-1) and ICS-164 (0.59 larvae plant-1). In case of A. janata the mean larval population in different genotypes ranged from 0.49 to 2.23 larvae plant-1. The lowest larval population was observed in the genotypes viz., DCS-107 (0.49 larvae plant-1), GC-3 (0.53 larvae plant-1), SKI-291 (0.53 larvae plant-1), DCS-9 (0.55 larvae plant-1), DCH-519 (0.56 larvae plant-1), 48-1 (0.59 larvae plant-1), DCS-8g (0.59 larvae plant-1), YTP-1 (0.60 larvae plant-1), GC-2 (0.63 larvae plant-1) and ICS-164 (0.64 larvae plant-1). The mean larval population of E. merione in xvi different genotypes ranged from 0.00 to 0.63 larvae plant-1. The lowest larval population was observed in the genotypes viz., YTP-1, DCS-9, DCS-8g and DCH-519 with zero larvae plant-1 followed by SKI-215 (0.04 larvae plant-1), GC-2 (0.13 larvae plant-1), JI-35 (0.13 larvae plant-1), ICS-164 (0.14 larvae plant-1), 48-1 (0.16 larvae plant-1), DCS-107 (0.16 larvae plant-1), SKI-291 (0.16 larvae plant-1) and GC-3 (0.17 larvae plant-1). As a part of studies on chaetotaxy of lepidopteran pest complex of castor, four lepidopteran larvae viz., S. litura, A. janata, E. merione and C. punctiferalis were collected and identified from the castor crop. All these lepidopteran larvae were described based on the morphological characters and chaetotaxy of thoracic and abdominal segments especially 3rd abdominal segment and arrangement of crochets on the ventral prolegs. The measurements viz., total length and width of the larva, length and width of head capsule, width across the compound eyes, length and width of thorax as well as abdomen were recorded. Field experiments on evaluation of certain selected insecticides against lepidopteran pest complex of castor revealed that, all the insecticide treatments were significantly superior over untreated control in the management of lepidopteran pest complex. The highest mean per cent reduction of lepidopteran pest complex over the control after three sprays was recorded with chlorantraniliprole 18.5 SC (0.0055 %) + azadirachtin 1 EC (0.01 %) @ 0.3 ml l-1 + 1 ml l-1 followed by chlorantraniliprole 18.5 SC (0.0055 %) @ 0.3 ml l-1 , cyantraniliprole 10.26 OD (0.0123 %) + azadirachtin 1 EC (0.01 %) @ 1.2 ml l-1 + 1 ml l-1, cyantraniliprole 10.26 OD (0.0123 %) @ 1.2 ml l-1), spinetoram 11.7 SC (0.0058 %) + azadirachtin 1 EC (0.01 %) @ 0.5 ml l-1 + 1 ml l-1, spinetoram 11.7 SC (0.0058 %) @ 0.5 ml l-1, chlorfluazuron 5.4 EC (0.0108 %) + azadirachtin 1 EC (0.01 %) @ 2 ml l-1 + 1 ml l-1, chlorfluazuron 5.4 EC (0.0108 %) @ 2 ml l-1 , quinalphos 25 EC (0.05 %) @ 2 ml l-1 and azadirachtin 1 EC (0.01 %) @ 1 ml l-1 . The highest capsule yield was recorded in the treatment chlorantraniliprole 18.5 SC (0.0055 %) + azadirachtin 1 EC (0.01 %) @ 0.3 ml l-1 + 1 ml l-1 (2369 kg ha-1) followed by chlorantraniliprole 18.5 SC (0.0055 %) @ 0.3 ml l-1 (2063 kg ha-1), cyantraniliprole 10.26 OD (0.0123 %) + azadirachtin 1 EC (0.01 %) @ 1.2 ml l-1 + 1 ml l-1 (1835 kg ha-1). Among all the treatments, the treatment chlorantraniliprole 18.5 SC (0.0055 %) + azadirachtin 1 EC (0.01 %) @ 0.3 ml l-1 + 1 ml l-1 emerged as the best treatment when compared with the other treatments with highest per cent reduction of lepidopteran pest complex of castor viz., S. litura (75.26 %), A. janata (82.31 %), E. merione (87.90 %) and C. punctiferalis (77.26 %) followed by chlorantraniliprole 18.5 % SC which was found to be the second best treatment against S. litura (68.80 %), A. janata (76.15 %), E. merione (82.71 %) and C. punctiferalis (73.46 %). The next effective treatment was cyantraniliprole 10.26 OD (0.0123 %) + azadirachtin 1 EC (0.01 %) @ 1.2 ml l-1 + 1 ml l-1was followed by cyantraniliprole 10.26 OD (0.0123 %).
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