Insects - Pests of Ornamental Trees, Shrubs and Flowers - page 49

Aulacorthum solani (Kaltenbach) ( 86 )
syn. Myzus pseudosolani (Theobald)
Glasshouse & potato aphid
In unheated situations, a generally common pest of
greenhouse-grown crops, including ornamentals such as
Capsicum, Geranium, Pelargonium and winter cherry
( Solanum capsicastrum ). Also present in summer on
various outdoor hosts. Virtually cosmopolitan. Widely
distributed in Europe.

DESCRIPTION
Apterous female: 1.2-2.6 mm long; shiny whitish to
greenish white, with blackish markings on the abdomen
which often form a horseshoe-shaped pattern; antennae
and legs mainly pale; siphunculi and cauda pale and
elongate. Alate: 1.6-2.4 mm long; similar to aptera.
Nymph: similar to adult but lacking the black body
pattern.

LIFE HISTORY
This species is entirely parthenogenetic. Breeding
continues throughout the year if conditions are
favourable but the aphids are usually most numerous in
the early spring. Winged forms occur occasionally, and
these help to spread infestations from plant to plant;
along with apterae, they are responsible for transmitting
certain plant viruses. Infestations often occur on
outdoor plants during the summer, particularly in
sheltered situations. The aphids excrete considerable
quantities of honeydew.

DESCRIPTION
Apterous female: 1.8-3.0 mm long; pear-shaped, shiny
greenish yellow, with darker patches at base of
siphunculi; antennae about as long as body; siphunculi
pale with dark tips, long, slender, tapered and distinctly
flanged. Alate: 1.8-3.0 mm long; head and thorax dark
brown to black; abdomen yellowish green, marked with
dark brown spots and crossbars. Nymph: yellowish
green and shiny, with dusky legs and antennae.

LIFE HISTORY
All stages overwinter, including eggs. In spring,
infestations spread to various hosts, both indoors and
outside. Colonies reach the peak of development in July
but largely die out by the autumn. In favourable
protected habitats the aphids continue to breed
parthenogenetically throughout the year, producing
both wingless and winged forms.

DAMAGE
Aphids occur on foliage and flowers, and heavy
infestations are directly harmful to many kinds of
ornamental plants; attacks on cyclamen and certain
lilies, e.g. calla lily, are particularly damaging. Infested
plants are often soiled by honeydew and sooty moulds;
they may also become infected by viruses, such as
dahlia mosaic virus, primula mosaic virus and tulip
breaking virus, which are commonly transmitted by this
species.

DAMAGE
Infestations weaken plants; they also spoil the
appearance and quality of hosts.

85

86

85 Colony of mottled arum aphid ( Aulacorthum
circumflexum ).

86 Glasshouse & potato aphid ( Aulacorthum solani ).