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
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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 %).