Agriculture Reference
In-Depth Information
Table 1. Duration (in days) of different periods of adult stage of the pea
aphid on four cultivated legumes in northwestern Ethiopia in 1998
and 1999*
Crop
species
Period in days (da
ys ± SE, N)
Pre-
reproductive
period**
Reproductive
Post-
reproductive**
Longevity
Faba
bean
0.9±0.1, 10 b
9.8±1.0, 10 c
1.0±0.1, 10 b
11.1±1.3, 10 c
Field pea 1.2±0.1, 10 a 9.8±0.6, 10 c 1.3±0.2, 10 b 22.7±1.5, 10
bc
Lentil 1.1±0.1, 9 a 17.4±0.9, 9 a 2.1±0.3, 9 b 25.2±1.5, 9 a
Grass pea 0.9±0.1, 9 ab 14.3±1.2, 9 b 0.7±0.0, 9 b 15.3±1.0, 9 b
*Mean separation by least significant difference test, α=0.05; means followed by
different letters within a column are significantly
different
from each other;
**Square root transformed values using the formula where
x
indicates
original values of duration in days. The original values of pre-reproductive and
post-reproductive period were more variable than reproductive period and
longevity and they required square root transformation to stabilize variance. N
stands for number of aphids tested.
x
0
c. Lifetime Fecundity
Basic life table parameters.
Whereas net reproductive rate was highest on
lentil (103.6 females/female), the rates of population increase was highest on
faba bean due the shorter generation time on it (Wale et al., 2000) (Table 2).
The second highest rate of population increase and reproductive rate was
observed on grass pea. The pea aphid doubled its population in less than three
days on all four crop species. The shortest pre-reproductive period was
recorded on faba bean.
Lifetime fecundity of the pea aphid was higher on lentil than on the other
crop species tested, followed by grass pea, faba bean and field pea (Table 3).
Pea aphids developing on lentil produced an average of 115 and on grass pea
83 nymphs. Pea aphids reared on faba bean and field pea had significantly
lower nymphal production than the other two. The difference in lifetime
fecundity was caused by higher daily reproduction on lentil (Table 3).
