Agriculture Reference
In-Depth Information
a vector of persistent and non-persistent viruses,
including bean yellow mosaic, bean leaf roll, beet
yellow net, pea enation mosaic and potato leaf
roll.
BIOLOGY
The winter is usually passed in the egg stage on
Euonymus europaeus
although, in favourable
situations, colonies may also survive the winter
on herbaceous hosts. Eggs hatch in the early
spring and colonies of aphids soon develop on
the young leaves and shoots. Winged forms ap-
pear in May or June and these disperse to vari-
ous herbaceous plants, colonies on the primary
host then dying out. Breeding on herbaceous
plants continues throughout the summer, with
the frequent production of winged forms and
further spread to other secondary hosts. Colo-
nies are often ant-attended, and are most popu-
lous in July and August. There is a return
migration to primary hosts in the autumn where
winter eggs are laid.
Fig. 189
Outline of front of head of various species
of aphid: (a) pea aphid,
Acyrthosiphon pisum;
(b)
black bean aphid,
Aphis fabae:
(c) glasshouse &
potato aphid,
Aulacorthum solani;
(d) strawberrv
aphid,
Chaetosiphon fragaefolii:
(e) rose/grain aphid.
Metopolophium dirhodum;
(f) peach/potato aphid.
Myzus persicae;
(g) damson/hop aphid,
Phorodon
humuli;
(h) bird-cherry aphid,
Rhopalosiphum padi.
DESCRIPTION
Aptera
1.5-3.0 mm long;
body
oval, usually dull
black (in older colonies, with conspicuous
patches of white wax on the abdomen);
antennae
much shorter than the body;
siphunculi
black
and tapered, and distinctly longer than the
cauda;
cauda
bluntly finger-shaped
(Fig. 188b);
head
with lateral tubercles no higher than the
median bulge
(Fig. 189b).
Aphis fabae
Scopoli
Black bean aphid
This well-known aphid is a major pest of field
bean, sugar beet and various other plants, includ-
ing vegetable crops such as broad bean, French
bean, red beet, runner bean and spinach; infesta-
tions also occur on minor field crops (including
quinoa) and on ornamental plants, some of which
are primary and others secondary hosts. Heavy
infestations on field and vegetable crops can
reduce yields significantly; leaves and shoots
may become malformed and plants noticeably
stunted. The aphids also contaminate host plants
with honeydew, upon which sooty moulds de-
velop; on field bean, chocolate spot disease can
also develop on excreted honeydew. The aphid is
Aphis gossypii
Glover
Melon & cotton aphid
This aphid is a major glasshouse pest, attacking
both ornamental and vegetable crops, especially
cucumber, melon and chrysanthemum. This spe-
cies is a complex of different races; specimens
associated with cucurbits, for example, do not
breed on chrysanthemum, and vice versa. Foli-
age of attacked plants turns yellow and may also
wilt and die. On cucumber and melon, infested
flowers may fail to open and fruitlets can be dis-
torted; crop yields and quality are also reduced
by the accumulation of honeydew and develop-
