Bt Research 2015, Vol.6, No.5, 1-10
4
larvae, followed by the treatments where larvae were
either fed with
Bt
maize (T2, 87.6%) or parasitized by
C. flavicincta
(T3,72%). In the treatments where the
larvae were both parasitized and fed with
Bt
maize for
only three days (Figure 2B), the results indicated
significant effectiveness in controlling
S. frugiperda
compared with the control (F= 10,2 gl= 3,8, p= 0.04).
Again treatment T4 was the most effective (71%). In
the groups where the larvae were either fed with
Bt
maize (T2) or parasitized by
C. flavicincta
(T3), the
average mortalities were 67.7 and 63.3%, respectively.
The data did not differ statistically.
1.2 Mortality bioassays of
Spodoptera frugiperda
parasitized by
Campoletis flavicincta
and infected
by the strains
Bt
thuringiensis
4412 (Cry1B) and
Bt.
kurstaki
HD1 (Cry1Ab)
In trials for assessing the mortality of larvae exposed
to
Bt thuringiensis
strain 4412 (Cry1B) and the
parasitoid
C. flavicincta
(Figure 4A), all treatments
were found to be effective, differing significantly from
the control (F= 42,5 df= 3,8 p= 0.000).
In the evaluation of the mortality of larvae exposed to
Bt kurstaki
strain HD1 (Cry1Ab) and the parasitoid
C.
Figure 3 Mortality of
Spodoptera frugiperda
subjected to different treatments for intervals of 3 to 10 days: (A) larvae exposed to
parasitism by
Campoletis flavicincta
and fed with
Bt
maize for ten days; (B) larvae exposed to parasitism and fed with
Bt
maize for
three days (the same letters indicate no significant difference by the Tukey test at a 5% probability)
Figure 4 Mortality of
Spodoptera frugiperda
larvae subjected to (A) the parasitoid and the
Bt thuringiensis
4412 strain (
cry
1B); or (B)
the parasitoid and the
Bt kurstaki
HD1 strain (
cry
1Ab). (the same letters indicate no significant difference by the Tukey test at 5%
probability)
