Biology Reference
In-Depth Information
92
Dysaphis tulipae (Boyer de Fonscolombe) ( 92 )
Tulip bulb aphid
A common pest of stored bulbs and corms, including
Crocus , Hippeastrum, Lilium and snowdrop ( Galanthus
nivalis ), but especially Gladiolus , Iris and tulip ( Tulipa );
also a virus vector. Virtually cosmopolitan. Widely
distributed in Europe.
DESCRIPTION
Apterous female: 1.5-2.5 mm long; pale yellowish,
greyish or pinkish brown, dusted with white wax;
siphunculi dark, tapered and relatively short; cauda
small and triangular. Alate: 1.5-2.3 mm long; abdomen
with a black dorsal mark and black siphunculi.
92 Colony of tulip bulb aphid ( Dysaphis tulipae ).
LIFE HISTORY
This entirely parthenogenetic aphid occurs on bulbs and
corms in store, breeding beneath the dried outer scales
throughout the year if conditions are favourable. When
infested bulbs or corms are planted out, aphid numbers
increase rapidly on the young shoots; later, the flowers,
flower spikes and developing seed pods may also
be colonized. Colonies are sometimes ant-attended
(cf. Rhopalosiphoninus spp., p. 70).
93
DAMAGE
Infestations severely check and distort the growth of
young shoots, and heavily infested bulbs and corms may
fail to develop. A vector of lily symptomless virus and
tulip breaking virus.
93 Colony of hawthorn/carrot aphid ( Dysaphis crataegi ) on
Crataegus .
Dysaphis crataegi (Kaltenbach) ( 93-94 )
Hawthorn/carrot aphid
This aphid overwinters in the egg stage on hawthorn
( Crataegus ), where spring colonies of blackish aphids
lightly dusted with wax inhabit conspicuous, deep-red
pseudo-galls on the leaves. Winged aphids later migrate
to wild and cultivated carrot ( Daucus carota ), where
they initiate dense, ant-attended colonies on the tap root
and leaf bases. Further winged forms then return to
hawthorn, the primary host, where winter eggs are laid.
94
Dysaphis sorbi (Kaltenbach) ( 95 )
syn. D. brevirostris (Börner)
Rowan aphid
Infestations of this aphid cause distortion of leaves of
rowan ( Sorbus aucuparia ), infested shoots becoming
contaminated with cast aphid skins, honeydew and
sooty moulds. Eggs overwinter on this primary host and
hatch in the spring. Colonies of aphids then develop
from April onwards, culminating in the production of
winged forms in late June or July. There is then a
migration to secondary (summer) hosts, such as bell
94 Gall of hawthorn/carrot aphid ( Dysaphis crataegi ) on leaf
of Crataegus .
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