International Journal of Horticulture, 2017,Vol.7, No.2, 7-19
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Figure 3 Fecundity of
Epilachna vigintioctopunctata
Fab. on
Solanum
melongena
,
S.
nigrum
and
Momordica
cochinchinensis
leaves. Different letters with in the rows
indicate the means (Mean ± SE of 3 observations) are
significantly different (
P
< 0.05, Tukey’s HSD) while
comparing one type of host plant with the other
Figure 4 Growth index (GI), of
Epilachna vigintioctopunctata
Fab. on
Solanum melongena
,
S. nigrum
and
Momordica
cochinchinensis
leaves. Different letters with in the rows
indicate the means (Mean ± SE of 3 observations) are
significantly different (
P
< 0.05, Tukey’s HSD) while
comparing one type of host plant with the other
1.3 Population dynamics
The population dynamics of
E. vigintioctopunctata
was calculated on their three host plant leaves,
S. melongena
,
S.
nigrum
and
M. cochinchinensis
, separately and showed different pattern with highly significant differences. The
three cohorts containing 146, 128 and 106 eggs for
S. melongena
,
S. nigrum
and
M. cochinchinensis
, respectively
were reared separately to construct the demographic data of
E. vigintioctopunctata
and they represent similar
pattern of development with significant variations (
P
< 0.05). The proportion of surviving (lx) and average
population alive in each stage (Lx) was also gradually decreased in the development of egg to adult stage on the
three host plants (Table 8; Table 9; and Table 10) which was always significantly higher on
S. melongena
than
S.
nigrum
and
M. cochinchinensis
. Life expectancy (ex) in egg and forth instar stages were higher on
S. nigrum
whereas in first, second, third instar and in pupal stages were higher on
S. melongena
leaves (Table 8; Table 9; and
Table 10). The killing power (Kx) was almost always higher on
M. cochinchinensis
than the other host plants
(Table 8; Table 9; and Table 10). Thus, the overall most vulnerable stage of
E. vigintioctopunctata
was found in
egg and pupal stages on all the three host plants.
Table 8 Stage-specific pooled life table of
Epilachna vigintioctopunctata
Fab. on
Solanum melongena
leaves (Mean of 3
observations)
Parameters
Egg
lnst- I
lnst- II
lnst- III
lnst- IV
Pupa
Adult
lx
0.406
0.306
0.283
0.267
0.247
0.211
0.178
dx
0.100
0.022
0.017
0.019
0.000
0.033
0.001
qx
0.247
0.073
0.059
0.073
0.000
0.158
0.001
sx
0.753
0.927
0.941
0.927
1.000
0.842
1.000
Lx
0.356
0.294
0.275
0.257
0.247
0.194
0.178
Tx
2.525
2.258
1.964
1.689
1.432
0.461
0.267
ex
6.226
7.391
6.931
6.333
5.792
2.184
1.500
kx
0.123
0.033
0.026
0.033
0.000
0.075
0.000
Table 9 Stage-specific pooled life table of
Epilachna vigintioctopunctata
Fab. on
Solanum nigrum
leaves (Mean of 3 observations)
Parameters
Egg
lnst- I
lnst- II
lnst- III
lnst- IV
Pupa
Adult
lx
0.356
0.283
0.261
0.239
0.208
0.192
0.161
dx
0.072
0.022
0.022
0.031
0.000
0.031
0.001
qx
0.203
0.078
0.085
0.128
0.000
0.159
0.001
sx
0.797
0.922
0.915
0.872
1.000
0.841
1.000
Lx
0.319
0.272
0.250
0.224
0.208
0.176
0.161
Tx
2.228
1.989
1.717
1.467
1.243
0.418
0.242
ex
6.266
7.020
6.574
6.140
5.967
2.181
1.500
kx
0.099
0.035
0.039
0.059
0.000
0.075
0.001
