Agriculture Reference
In-Depth Information
nies develop on these plants in the spring;
winged forms are produced relatively early in the
season, and these migrate to peas and beans
from May onwards. These immigrants infest the
growing points, and infestations are often over-
looked until colonies build-up on the foliage or
developing pods. The aphids, which drop readily
to the ground when disturbed, often form signifi-
cant infestations in June and July; colonies on
summer hosts usually persist until the autumn.
DESCRIPTION
Aptera
2.5-4.0mm long;
body
elongate, pale
green to yellowish or pinkish;
antennae, legs and
cauda
long, slender;
siphunculi
very long, slender
and dark tipped
(Fig. 188a);
head
deeply in-
dented
(Fig. 189a). Nymph
similar to adult but
with a slight waxy coating.
Amphorophora idaei
(Borner)
Large raspberry aphid
Although commonly associated with wild and
cultivated raspberry, and closely related plants
(but not blackberry), this aphid is rarely numer-
ous and is of significance mainly as a vector of
raspberry leaf spot and raspberry mosaic viruses.
BIOLOGY
This species overwinters in the egg stage.
Nymphs appear from early March onwards and
then feed on the tips of the developing buds.
Later, they invade the underside of expanded
leaves. The aphids are usually present in rela-
tively small numbers and do not form dense colo-
nies (cf. small raspberry aphid,
Aphis idaei,
p.
108). In June and July, after two generations of
wingless forms, winged aphids are produced, and
these are responsible for spreading infestations.
Sexual forms, including alate males, occur in the
autumn. Winter eggs are deposited on the canes
by oviparae from October onwards.
Fig. 188
Siphunculi and caudas of some aphids
associated with salad or vegetable crops: (a) pea
aphid.
Acyrthosiphon pisum;
(b) black bean aphid,
Aphis fabae;
(c) melon & cotton aphid,
Aphis
gossypik
(d) cabbage aphid,
Brevicoryne brassicae;
(e) vetch aphid
Megoura viciae;
(f) currant/lettuce
aphid,
Nasonovia ribisnigri.
Amphorophora rubi
(Kaltenbach)
Bramble aphid
This medium-sized to large (2.5-4.0 mm long),
shiny green to yellowish-green species is gener-
ally common on
Rubus fruticosus,
including
cultivated blackberry. It is very similar in ap-
pearance to
Amphorophora idaei
(above), with
which it was once confused, but does not infest
raspberry and is not an important pest. This spe-
cies sometimes overwinters anholocyclically.
DESCRIPTION
Aptera
2.6-4.1 mm long, shiny, pale yellowish-
green to green;
antennae and legs
long and
slender;
siphunculi
pale, elongate and slightly
swollen on the apical half, with the tip flanged;
cauda
finger-shaped.
