Agriculture Reference
In-Depth Information
DESCRIPTION
Aptera
2.1-2.6 mm long, pinkish to dark bluish-
grey, coated with white, mealy wax;
siphunculi
black, elongate, tapered, flanged apically;
cauda
dark, triangular
(Fig. 191d).
transmitting various virus diseases, including
cauliflower mosaic, celery crinkle leaf and celery
mosaic.
Dysaphis crataegi
(Kaltenbach)
Hawthorn/carrot aphid
Dysaphis pyri
(Boyer de Fonscolombe)
Pear/bedstraw aphid
This aphid overwinters in the egg stage on
Crataegus,
where spring colonies of blackish
aphids, lightly dusted with wax, form con-
spicuous, deep-red pseudo-galls on the leaves.
Winged aphids later migrate to wild and culti-
vated carrot, where they initiate dense, ant-
attended colonies of wingless aphids on the tap
root and leaf bases; aphids also occur in summer
on parsnip
(Plate 2c),
as a separate subspecies:
Dysaphis crataegi kunzei
(Borner) = hawthorn/
parsnip aphid. In the autumn, winged forms are
produced, and these return to
Crataegus
where
winter eggs are laid. Apterae on carrot and pars-
nip are 1.4-2.6mm long, yellowish-grey, green-
ish-grey or pinkish-grey, and lightly dusted with
wax; the siphunculi are relatively short and dis-
tinctly tapered.
The pear/bedstraw aphid is a potentially impor-
tant pest of pear. Infestations lead to consider-
able distortion and yellowing of foliage and have
a deleterious effect on shoot growth. The aphids
also contaminate host plants with vast quantities
of honeydew.
BIOLOGY
This species overwinters as eggs on pear, the
primary host. Colonies develop during the spring
on the young leaves and shoots, often becoming
very populous. Winged forms are usually pro-
duced in June, and these migrate to
Galium
the
secondary, summer host. Winged migrants from
Galium
eventually return to pear in the autumn.
DESCRIPTION
Aptera
1.7-3.2mm long, distinctly plump,
brownish-red to dark brown but coated in whit-
ish wax, which gives the body a pinkish appear-
ance;
siphunculi
black;
cauda
short, tongue-like.
Dysaphis tulipae
(Boyer de Fonscolombe)
Tulip bulb aphid
This virtually cosmopolitan aphid is associ-
ated with monocotyledonous plants and is an
important pest of various ornamentals, causing
both direct damage and also acting as a virus
vector. It is often abundant on iris, lily and
tulip, and large numbers often cluster on young
shoots sprouting from corms or bulbs. Apterae
are 1.5-2.5 mm long, grey, pink or whitish-
yellow, and covered in a white, powdery wax.
This species is anholocyclic, breeding entirely
parthenogenetically.
Dysaphis apiifolia petroselini
(Borner)
Hawthorn/parsley aphid
This common species forms red pseudo-galls on
leaves of
Crataegus
during the spring, and mi-
grates in summer to the base of the stems of
celery and parsley. Colonies on these summer
hosts are commonly sheltered by ant-constructed
earthen canopies. The aphids are similar in ap-
pearance to the more widely known
Dysaphis
crataegi
(below) but with a distinct rust-coloured
patch around the base of each siphunculus.
Damage caused to primary and secondary hosts
is of little or no importance but, at least under
laboratory conditions, the aphids are capable of
Hyalopterus pruni
(Geoffroy)
Mealy plum aphid
This aphid is a generally common pest of damson
and plum; infestations also occur on certain wild
