122 M. Chandrashekharaiah et al.
Rubiales 2009). Sabbour ( 2012 ) evaluated nano
aluminium oxide (Al 2 O 3 ) and titanium diox-
ide (TiO 2 ) against rice weevil Sitophilus oryzae
(Coleoptera: Curculionidae). Nano Al 2 O 3 found
highly effective against S. oryzae and nano TiO 2
has low to moderately effective against S. oryzae.
Silica nanoparticle (SNP) was evaluated Debnath
et al. ( 2011 ) against S. oryzae and its efficacy
was compared with bulk-sized silica (individual
particles larger than 1 lm). Amorphous SNP was
highly effective against this insect pest causing
more than 90 % mortality.
Effect of Tebufenozide—A Moult
Inducing Growth Regulator
on Helicoverpa armigera Larvae
Effect of tebufenozide on the neonate and fourth
instar larvae of H. armigera (Lepidoptera: Noc-
tuidae) was recorded through feeding for 96 h
and then transferred the larvae to normal diet.
At lower concentrations of IGR, i.e., at 1.0 and
2.5 ppm, behavior of the larvae was normal on the
1st DAT. Larvae showed taxis towards the source
and palpated on the diet. However, at higher con-
centrations of IGR, i.e., at 10 and 20 ppm, lar-
vae exhibited kinesis (undirected orientation and
movements), larvae turned sluggish and treated
diet surface inhibited feeding in larvae. After
18 days, the compound resulted in 100 % lar-
val mortality. Study clearly denoted significant
change in the developmental processes of newly
borne larvae H. armigera larvae. The sensitiv-
ity was observed after about 60 h of feeding on
tebufenozide. This insect growth regulator dis-
rupted the normal development of neonate larvae
subsequently in a more or less dose-dependent
manner (Table 4 ). At 0.10 ppm, average of single
neonate larval weight after 7 days from the start
of the experiment was 64.46 ± 2.82 mg. In control,
the neonate larval weight after 7 days from the
start of the experiment was 78.52 ± 2.61 mg. At
the lowest concentration of 0.10 ppm, tebufeno-
zide failed to exert influence on the pupal weight
(Table 4 ). However, with subsequent increase in
concentration pupal weights (163.51 ± 18.20 mg
and 124.63 ± 8.56 mg) differed significantly from
control (208.52 ± 12.12 mg) (Table 4 ). Concentra-
tion gradient effect of tebufenozide was also re-
flected in the neonate larval weights taken 7 days
after the experiment. The average pupal weight
at 0.25 ppm was 163.51 ± 18.20 mg and at dose
0.50 ppm, it was 124.63 ± 8.56 mg, respectively.
Fourth instar larvae of fruit borer fed on syn-
thetic diet treated with tebufenozide for 96 h
disrupted the development in a dose-dependent
manner. This disruption of growth was reflected
in the maximum average larval weight as well as
average pupal weight (Table 2 ). Average pupal
weight in all concentrations differed significantly
from control (Table 2 ). There were no significant
differences in average fourth instar larval weight
after 7 days. Data denoted that at 10 and 20 ppm
pupation did not take place since 100 % larval
mortality occurred on day 7 (Table 5 ). Both first
and fourth instars larvae of H. armigera after
tebufenozide reduced intake of food, growth and
caused rupture of the cuticle, resulting in malfor-
mation and mortality.Tebufeno-
zide (conc.
ppm)Average single
larval weight after 7
days (mg) (X ± SE)Average larval
weight (mg)
(X ± SE)Day 100 %
larval mortal-
ity occurredAverage single
pupal weight
(mg) (X ± SE)
Control 78.52 ± 2.61a 506.51 ± 1 1.50a – 208.52 ± 12.12a
0.10 64.46 ± 2.82b 325.63 ± 7.16b – 197.47 ± 15.36a
0.25 60.57 ± 2.43b 309.47 ± 15.60b – 163.51 ± 18.20b
0.50 52.51 ± 5.01c 270.54 ± 1 1.76c – 124.63 ± 8.56c
1.00 30.27 ± 1.73d 264.32 ± 20.48c 16 –
2.50 27.64 ± 1.84d 146.57 ± 14.28d 14 –
5.00 14.23 ± 1.43e 70.51 ± 7.36e 12 –
Experiment terminated 48 h after treatment; means followed by the same letter are not
significantly different ( p < 0.01; one-way ANOVA followed by Tukey–Kramer test)Table 4 Effect of feeding
on tebufenozide (RH-
5992) treated diet on the
developmental responses
of neonate larvae of H.
armigera for 48 h