Agriculture Reference
In-Depth Information
Macrosiphum
rosae
(L.)
Rose aphid
tions also occur on grasses. Damage is rarely
important, but 'outbreak' years are known in
which very large populations develop and yield
reductions occur. On wheat and barley, aphids
developing on flag leaves from ear emergence
onwards are of greatest significance; on maize
and sweet corn, the aphids are of only minor
importance unless very numerous. Colonies on
rose bushes have little direct effect on plant
growth.
This aphid is a major pest of rose. Colonies
often persist on rose bushes throughout the year,
overwintering in the egg stage, but a summer
migration to secondary hosts (including Dip-
sacaceae and Valerianaceae) also occurs. The
medium-sized to relatively large aphids (up to
3.6mm long) are broadly spindle-shaped and
shiny; they vary in colour from green to pink or
reddish-brown, and have long antennae, legs and
siphunculi; the siphunculi are characteristically
black and shiny.
BIOLOGY
This species overwinters in the egg stage on wild
and cultivated rose bushes where, in spring,
colonies develop on the leaves and flower buds.
Winged forms are produced from April or early
May onwards. These aphids migrate to cereals
and grasses, where breeding continues; colonies
on rose do not persist beyond June (cf. rose
aphid,
Macrosiphum rosae,
above). On cereals,
the aphids are restricted mainly to the lower
leaves but, especially if numerous, they may in-
vade the upper leaves, including the flag leaves.
The aphids feed mainly beneath the leaves and,
although dislodged by gusts of wind, usually
remain undisturbed by rain (cf. grain aphid,
Sitobion avenae,
p. 120). Colony decline on
Poaceae is followed by a return migration to
rose, the primary host; winter eggs are laid in
October and November. In mild, ideally damp
situations, the aphids are capable of surviving the
winter pathenogenetically on grasses.
Megoura viciae
Buckton
Vetch aphid
Minor infestations of this aphid occur on various
members of the Fabaceae, including broad bean,
culinary pea and vetches. Heavily infested parts
of plants become discoloured, the affected tissue
turning red and eventually black; damage, how-
ever, is rarely important. The aphids are also
vectors of several viruses, including bean enation
mosaic and bean leaf roll.
BIOLOGY
Eggs overwintering on host plants hatch in the
spring from early April onwards. After about
three generations of wingless forms, winged
aphids are produced, and these spread infesta-
tions to other locations. Breeding continues until
the autumn when populations reach their peak
and, eventually, winter eggs are laid.
DESCRIPTION
Aptera
1.5-3.0 mm long;
body
broadly spindle-
shaped, pale green (rarely pink) with a dark
longitudinal stripe dorsally;
siphunculi
long and
pale;
cauda
broadly finger-shaped
(Fig. 193a);
head
with divergent lateral prominences and a
distinct median prominence (outline, therefore,
W-shaped)
(Fig. 189e).
DESCRIPTION
Aptera
3.0-4.3 mm long,
body
spindle-shaped,
mainly green to dark bluish-green;
head, anten-
nae, prothorax and legs
black;
siphunculi
black
and distinctly swollen;
cauda
black and finger-
shaped
(Fig. 188e).
Metopolophium dirhodum
(Walker)
Rose/grain aphid
Metopolophium festucae
(Theobald)
Fescue aphid
This aphid is a potentially harmful pest of cere-
als, especially winter wheat and barley; infesta-
This species is associated mainly with grasses,
but will also occur on cereals, overwintering
