Agriculture Reference
In-Depth Information
Table 2. Life table parameters for
A. pisum
reared on different
food legumes
Net reproductive
rate
Mean generation
time (days)
Intrinsic rate of
increase
Doubling time
(days)
R
o
r
Faba bean 59.40 14.27 0.286 2.42
Field pea 62.59 16.04 0.256 2.69
Lentil 103.56 18.07 0.257 2.70
Grass pea 82.90 16.02 0.276 2.51
*Mean separation by least signi
ficant diffe
rence test, α=0.05; **Square root transformed
x
0
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.
Table 3. Life-time fecundity and mean daily reproduction of A.pisum
reared on different food legumes
Crop
species
Reproduction
Number of nymphs
(Nymphs/
female±SE, N)
Range
Number/day/female
(Nymphs±SE, N)
Range
Faba bean 59.7±5.8, 10 c 35-89 6.2±1.8, 10 ab 1-9
Field pea 57.9±4.0, 10 c 42-86 5.3±0.9, 10 b 0-8
Lentil 115.1±5.3, 9 b 89-145 6.7±0.6, 9 a 0-12
Grass pea 82.9±7.7, 9 b 35-127 5.4±0.9, 9 b 1-8
*Mean separation by least significant difference test, α=0.05; means followed by
different letters within a column are significantly different from each other.
Reproductive curve.
Pea aphids produced more nymphs per day on lentil
than on other crops (Wale et al., 2000). The peak daily nymphal production
was recorded from adults aged between 6 and 10 days. Reproduction
continued for 21 days on lentil, 19 days on grass pea, 18 days on field pea and
16 days on faba bean. After a break of about one week, reproduction on lentil
resumed, and produced a small second peak between 27 and 30 days of adult
age. On other crops there was no second peak and daily reproduction
progressively declined until it reached nil. The mean daily reproduction of pea
aphids, obtained by dividing the total number of nymphs produced per aphid
by the number of days the aphid produced the nymphs, was significantly
higher on lentil, followed by faba bean. Differences among the rest of the host
plants were not significant. A maximum of 12 nymphs/day was recorded on
