screening elite genotypes and ipm of defoliators in groundnut

Sreenivasa et al. (1997) studied on the development of S. litura as influenced by
groundnut genotypes. In laboratory studies, larval mortality of S. litura was highest on the
groundnut variety ICGV 86031 (82.8%) followed by ICGV 86350 (53.32%) and Dh-3-30
(43.02%). Development was shortest (32.25 days) on Dh-3-30 with adults surviving for a
maximum of 10.5 days and longest (37.5 days) development on ICGV 86031 with adults
surviving a maximum of 9.50 days. ICGV 86350 was intermediate.
S. litura reared on EMS treated Valencia mutants at Dharwad, Karnataka, showed
that mutant 28-2 and 45 consistently showed less leaf damage, high mortality, low weight and
low gain in weight of larvae compared to susceptible check (JL-24) and parents (DER and VL
1) at all stages. The mortality and gain weight was very much pronounced on neonate larvae.
The resistance effect of these mutants also extended the larval period by three days and had
pronounced effect on the fecundity of moths indicating resistance in the mutants (Prasad et
al., 2000). Leuk and Skinner (1971) reported that the mean length of the life cycle of
Spodoptera frugiperda (S.) was shorter (29 days) for the susceptible Starr than South Eastern
runner (33.3 days). The mean percentage of moth emergence was significantly less for larvae
fed on foliage of the resistant cultivar, south eastern runner and the mortality of the total
insects fed with the foliages was higher at all the stages of larval development and pupation
on south eastern runner than starr.
According to Patil et al. (2005) the investigations have been carried out for four years
from 1996 to 1999 involving elite genotypes of groundnut to assess the yielding potentiality
over different agroclimatological conditions and also understand the mechanism of resistance
to major defoliator S. litura. Among the genotypes Dh-53 surpassed all other entries for pod
yield under unprotected conditions and hence considered to be a resistant variety of
groundnut against S. litura.
In the laboratory condition, rearing of insect on resistant genotypes like NC Ac 343,
Mutant 28-2 and R 9227 affected larval growth and survival, pupal development, adult
emergence and fecundity indicating antibiosis as the principal mechanism of resistance
(Prasad and Gowda, 2006).
Patil et al. (2009) investigated the presence of resistance mechanism in elite
genotypes of groundnut against S. litura. Eleven genotypes of groundnut such as TR-1-16-2,
R-D-1-51, MN-1-35, DCG-17, M-1-28,R-9227, Dh-4-3, Dh-53, R-2001-2, ICGV-86590 and
Dh-3-30 were evaluated. The variation in larval development and pupal weight after feeding
on these groundnut varieties were taken as criteria and subjected to analysis. The larvae fed
on leaves of MN-1-35, R-9227, DCG-17, M-1-28, Dh-53 & TR-1-16-2 recorded low to
moderate larval weight and lower pupal weight. Higher larval and pupal weight was recorded
in larvae fed on leaves of ICGV-86590, R-2001-2 and Dh-3-30. The results clearly indicated
the presence of resistance mechanism in some groundnut genotypes against the S. litura.
2.2 Different components of IPM for S.litura
2.2.1 Seasonal incidence of S. litura measured by the use of pheromone
traps
Sreedhar (1983) monitored the activity of S. litura moths in cabbage fields at two
locations in Karnataka using sex pheromone traps and found peak moth catches during last
week of February at Raichur and during second week of March at Dharwad. However,
Kulkarni (1989) noticed this pest to be active throughout the year at Dharwad. But more moth
catch was seen from June to October with peak moth activity during September.
Pawar and Shrivastava (1988) tried pheromone traps baited with lure of S. litura and
H. armigera separately and together in a groundnut field in Andhra Pradesh. There was no
difference in catches of S. litura in traps with any one of the lures or a combination of both the
lures.