Agriculture Reference
In-Depth Information
50
Faba bean
Field pea
Lentil
Grass pea
40
30
20
10
0
2
6
10
14
Number of aphids/plant
Figure 2. Number of nymphs produced per aphid at various aphid densities per plant
on four legumes.
On the other hand, daily nymphal production was significantly affected by
aphid density per plant. On faba bean, 2 aphids/ plant gave the highest daily
reproduction, while 14 aphids/ plant had the lowest. Reproduction showed a
decreasing trend as aphid density increased in all test crop species. For all
aphid densities, reproduction started to decline after 8 days on each of faba
bean and grass pea, after 6 days on field pea and lentil (Wale et al., 2003b).
6.
P
OPULATION
D
YNAMICS
Basic estimates of populations are required in integrated pest management
in order to understand the population dynamics of a pest species and as the
basis for making management decisions relating to monitoring and forecasting
levels of pest abundance and distribution (Dent, 2000). Absolute estimates of
aphids per unit plant were recorded.
The population dynamics of pea aphids was investigated on field peas at
two locations: Adet (relatively cooler area at 2240 m altitude) and Zema
(warmer and lower than 2000 m altitude) for three years (seasons), i.e., 1994,
1995 and 1996.
The cooler location is located at 11
o
17‟ N latitude and 37
o
43‟ longitudes
on an altitude of 2240 m above sea level. The center receives average annual
rainfall of 1271 mm and temperature ranging from 8.8-25.2
o
C (ARC, 2011).
