Agriculture Reference
In-Depth Information
ment of sooty moulds. The aphids are vectors of
viruses, including cucumber mosaic.
BIOLOGY
This entirely parthenogenetic (anholocyclic)
species breeds continuously under protection,
producing both winged and wingless forms.
Colonies are frequently ant-attended and often
become very populous. In densely populated
colonies, if temperatures are high, the adult
aphids are often smaller than normal. Infesta-
tions may occur on outdoor plants during the
summer but, in Northern Europe, the aphids are
unlikely to survive the winter out-of-doors.
DESCRIPTION
Aptera
0.9-1.9 mm long;
body
pear-shaped, usu-
ally green or yellowish-green to dark green, blue-
green or blackish (dwarf specimens, often no
longer than 1mm, usually creamish or whitish);
siphunculi
dark, moderately long and tapered;
cauda
narrow and elongate
(Fig. 188c).
Aphis nasturtii
Kaltenbach
Buckthorn/potato aphid
This generally common species is a minor pest
of certain vegetable crops, especially potato and
watercress. The aphids cause little direct damage
and tend to be of greater significance as vectors
of viruses, including potato virus A, potato virus
Y and turnip mosaic.
Fig. 190
Siphunculi and caudas of some aphids
associated with bulb or potato crops: (a) buckthorn/
potato aphid,
Aphis nasturtii;
(b) glasshouse &
potato aphid,
Aulacorthum solani;
(c) potato aphid,
Macrosiphum euphorbiae;
(d) shallot aphid,
Myzus
ascalonicus;
(e) peach/potato aphid,
Myzus persicae;
(f) bulb & potato aphid,
Rhopalosiphoninus
latysiphon;
(g) mangold aphid,
Rhopalosiphoninus
staphyleae tulipaellus.
BIOLOGY
This aphid overwinters in the egg stage on
Rhamnus.
Colonies develop during the spring
from April onwards and, in June, winged forms
migrate to a wide variety of summer hosts, in-
cluding potato, tomato and watercress. Breeding
continues on these hosts until a return migration
to
Rhamnus
takes place in early September.
Aphis grossulariae
Kaltenbach
Gooseberry aphid
This small (1.5-2.2 mm long), greyish-green
species overwinters in the egg stage on goose-
berry. Colonies develop in the spring at the shoot
tips, and attacks often cause significant distortion
of the new growth; heavily infested bushes may
become stunted. The aphids are also vectors
of gooseberry veinbanding virus. Winged aphids
migrate in summer to secondary hosts such as
DESCRIPTION
Aptera
1.1-2.2 mm long, bright yellow to
yellowish-green;
antennae
much shorter than
body;
siphunculi
short, pale with dusky tips but
often entirely brown;
cauda
short and tapered
(Fig. 190a).
