screening elite genotypes and ipm of defoliators in groundnut

Third instar duration was significantly longer on the genotypes ICGV-86699 Tan (3.83
days) and Mutant III (3.75 days) followed by GPBD-6 (3.25 days) and GPBD-5 (3.25 days)
and were on par with JL-24 (3.08 days), GPBD-4 (3.00 days) and ICGV- 86699 Red (3.00
days).
4.1.1.1.4 Fourth instar
The color of the fourth instar larvae was grayish to black with a dark head and three
white spots were observed on cervix. On meso and metathoracic segments white spots were
seen on the lateral sides along the black stripes. The larvae got scattered from the egg laying
site and fed on the leaves irregularly from the margin inwards.
The duration of fourth instar was significantly longer on the resistant genotypes,
ICGV- 86699 Tan (4.33 days) and Mutant III (4.17 days) followed by GPBD-5 (3.83 days),
GPBD-6 (3.67 days) and ICGV- 86699 Red (3.67 days). The shortest larval duration was
recorded in susceptible genotypes GPBD-4 (3.25 days) and JL-24 (3.17 days).
4.1.1.1.5 Fifth instar
Considerable variation in the color ranging from light green to dark brown with a dark
brown head was apparent. A prominent ‘Y’ shaped epicranial suture was present on the head.
The lateral stripes were more clearly visible from a distance. Larvae were more gregarious
and fed irregularly on the leaves from margin inwards.
The duration of fifth larval instar was significantly longer in the genotypes, ICGV-
86699 Tan (4.75 days) and Mutant III (4.58 days) followed by GPBD-5 (3.92 days), and
GPBD-6 (3.90 days) and were on par with ICGV- 86699 Red (3.42 days). The least larval
duration was recorded in susceptible genotypes GPBD-4 (3.33 days) and JL-24 (3.25 days).
4.1.1.1.6 Sixth instar
The full grown sixth instar larva was stout and smooth. It was dull grayish to blackish
green in color with a bright yellow stripes bordered by semicircular stripe. Along the lower
edge of lateral side of the body, dull yellow stripe was distinct. On the dark brown head
inverted ‘Y’ shaped suture was prominent.
The duration of last instar was significantly longer in the resistant genotypes, ICGV-
86699 Tan (4.92 days) and Mutant III (4.83 days) followed by GPBD-5 (4.08 days), and
GPBD-6 (4.09 days) and shortest larval duration was noticed in ICGV- 86699 Red (3.42
days).However, it was on par with JL-24 (3. 52 days) and GPBD-4 (3.50 days).
4.1.1.1.7 Total larval period
The total larval period on all the genotypes ranged from 17.33 to 23.67 days. The
resistant genotypes, ICGV- 86699 Tan and Mutant III permitted the larvae to complete their
development in longer period (23.67 days and 22.83 days respectively) followed by GPBD-5
(19.75 days) and GPBD-6 (19.49 days) and ICGV- 86699 Red (18.17 days). The susceptible
varieties JL-24 and GPBD-4 allowed the larvae to complete their larval period within shortest
period (17.93 days and 17.33 days) (Table 2).
4.1.1.2 Larval weight
Mean of 20 larval weight was recorded on each genotype at 5, 10 and 15 days after
hatching. The weight gain by the larvae after 5 days after hatching (DAH) was maximum on
susceptible genotypes, JL-24 (0.08 g) and GPBD-4 (0.08 g) followed by GPBD-5 (0.06 g) and
minimum weight was recorded in resistant genotypes, ICGV- 86699 Tan (0.02 g) and Mutant
III (0.02 g) and remaining genotypes were on par with each other (Table 3).
After 10 DAH, the larval weight was significantly highest on JL-24 (1.98 g) and
GPBD-4 (1.91 g) followed by GPBD-6 (1.44 g), GPBD-5 (1.41 g) ICGV-86699 Red (1.28 g).