Agriculture Reference
In-Depth Information
lentil, 9 on field pea and faba bean, and 8 on grass pea. This indicates that the
pea aphid varies in its daily reproduction due to differences in host plant and
here lentil is more susceptible to damage by pea aphids than are field pea,
grass pea and faba bean. Similar differences have been reported on other
leguminous plants elsewhere (Kaakeh and Ducther, 1993).
Effect of minimum and maximum temperatures on aphid survival and
reproduction was computed. Significant relationship was obtained between
daily nymphal production and minimum temperature on lentil alone (F=4.61,
P<0.05). The relationship of aphid survival and minimum temperature was
also nearly significant (F=4.07, P=0.06). There was no discernible relationship
between survival/reproduction and maximum temperature.
4.
W
ILD AND
C
ULTIVATED
H
OSTS OF
P
EA
A
PHID
These are legumes (perennial or annual) that grow wild or are cultivated
for fodder or for other purposes. They do not belong to food-legumes. We
found clover (wild), vetch and pigeon pea (cultivated) that are infested by pea
aphids.
In a field survey carried out in 1999 and 2000 in West Gojam,
northwestern Ethiopia, wild or cultivated annual and perennial legume plants
were sampled for the presence of pea aphids on 0.5× 0.5 m
2
quadrates which
were selected randomly (Wale et al., 2003a).
In case of annual plants, pea aphids infested vetches (
Vicia
spp.) and
clover (
Trifolium ruepellanium
Fresen) significantly (χ
2
=245.7, P=0.005). This
was not found to be the case on lupine (
Lupinus
spp.) and alfalfa (
Medicago
sativa
L.). Aphids infested flowers of clover, and flowers, leaves, and stems of
vetch. Despite the search for its existence on many perennial trees, pea aphid
was consistently found only on the perennial pigeon pea (
Cajanus cajan
)
plants throughout the year and not on others such as sesbania,
Sesbania sesban
(L.) Merr.
Clover plants were found growing in pasturelands and as undergrowth
beneath large cereals such as maize and sorghum or even under small cereals
such as wheat and barley. Clover plants were found infested more in October
when the plants flowered and set pods as compared to other times of the year
(Wale et al., 2003a). From December onwards, these plants almost
disappeared except in very wet conditions such as near leaking water taps,
irrigation channels and stream banks. Clover plant density and aphid numbers
