Development, Characterization and Field Assessment of Multiple Insecticides ... 343
of H. armigera at all the plots. The MIHTTS re-
leased indicated its ability to survive in higher
proportion than laboratory population and that of
natural parasitoid population in farmers practice
plots and untreated control. The higher parasit-
ism by MIHTTS compared to susceptible strain
plots could be due to its tolerance to various in-
secticides in sprayed situation in the field.
The mean percent damage of fruits increased
significantly in different treatments. The percent
fruit damage in MIHTTS plots ranged from 0.78
compared to 4.05 per plant in susceptible strain
and 0.91 per plant in farmers’ practice plots and
damage was highest in untreated control where
it was 11.5 per plant. The larval population per
plant also increased with increase in load of eggs,
however, larval population was significantly less
in MIHTTS plots + insecticide treated plots com-
pared to susceptible strain + insecticides, farm-
ers’ practice plots and untreated control. The
yield recorded was highest in MIHTTS plots
- insecticides plots 495.0 compared to 407.1,
421.5, and 257.4 q/ha in susceptible strain plots,
farmers’ practice plots and untreated control, re-
spectively (Table 12 ).
During 2nd year trial, egg parasitism by
Trichogramma in various plots before initia-
tion of releases was very low ranging from 0.0
to 1.0 %. The post treatment egg parasitism in
MIHTTS plots (65.5 %) was significantly higher
than egg parasitism by susceptible strain plots
(27.2 %), farmers’ practice (8.8 %) and untreated
control (12.6 %). In general in farmers practice
plots egg parasitism was least, even lesser than
untreated control (Table 13 ). The releases of T.
chilonis commenced with moth capture in phero-
mone traps and coincided with period of egg lay-
ing of H. armigera at all the plots. The MIHTTS
plots released indicated its ability to survive in
higher proportion than susceptible strain plots
and that of natural parasitoid population in farm-
ers’ practice plots and untreated control. The
higher parasitism by MIHTTS compared to sus-
ceptible strain could be due to its tolerance to var-
ious insecticides in sprayed situation in the field.
The mean percent damage of fruits increased
significantly in different treatments. The larval
population per plant also increased with increase
in load of eggs, however, larval population was
significantly less in MIHTTS plots + insecticide
treated plots (1.8/plant) compared to susceptible
strain + insecticides (3.6/plant), farmers’ prac-
tice plots (1.9/plant)) and untreated control (4.8/
plant). The percent fruit damage in MIHTTS
plots ranged from 1.17 %, susceptible strain
7.11 %, farmers’ practice 2.2 %, and damage was
highest in untreated control where it was 14.65 %.
The yield recorded was highest in MIHTTS + in-
secticides plots (502 q/ha) compared to 364 q/ha
in susceptible strain + insecticides, 419.0 q/ha
in farmers’ practice plots and untreated control
(236 q/ha), respectively (Table 13 ).Cabbage
In the field evaluation studies during 1st year, no
egg parasitism was recorded by Trichogramma in
any treatments. The post treatment egg parasitism
in MIHTTS of T. chilonis plots was significantly
higher (35.0 %) than egg parasitism by suscep-
tible strain (1.2 %), farmers’ practice (0.0 %) and
untreated control (2.0 %). The MIHTTS released,
indicated its ability to survive in higher propor-
tion than susceptible strain. The higher parasit-
ism by MIHTTS compared to susceptible strain
could be due to its tolerance to various insecti-
cides in sprayed situation in the field (Table 14 ).Table 13 Effect of field release of MIHTTS of T. chilonis on percent egg parasitism and larval population of H. armi-
gera on tomato in Malur (Karnataka) during 2nd year trial
Treatments Egg parasitism (%) No. of larvae/plant % fruit bored Yield (q/ha)
MIHTTS of T. chilonis 65.5 1.8 1.17 502.0
Susceptible strain 27.2 3.6 7.11 364.0
Farmers’ practice 8.8 1.9 2.20 419.0
Untreated control 12.6 4.8 14.65 236.0
SEM. ( ± ) 1.9 0.85 1.12 3.39
LSD (0.05) 5.47 1.88 1.95 12.56
LSD (0.01) 9.36 3.14 3.34 23.48
CV (%) 14.44 18.52 19.78 12.45