Agriculture Reference
In-Depth Information
Epilobium, with a return migration to goose-
berry in the autumn.
Aphis idaei van der Goot
Small raspberry aphid
This aphid causes leaf curl on loganberry and
raspberry, but is of greater importance as a vec-
tor of raspberry vein chlorosis virus. Eggs, which
overwinter on the canes, hatch in March. Dense
colonies then develop on the shoots, buds and
flower trusses; such colonies are usually ant-
attended. The apterous females within these
colonies are 1.5-2.0 mm long and pale green
to yellowish-green, with moderately long, out-
wardly curved siphunculi. Winged forms are
reared during the summer and these disperse to
the new canes, eventually giving rise to small,
pale yellow apterae which develop singly on the
underside of expanded leaves. Wingless sexual
forms are produced in the autumn.
Aphis pomi Degeer
Green apple aphid
Fig. 191 Siphunculi and caudas of some aphids
associated with fruit trees: (a) green apple aphid,
Aphis pomi; (b) leaf-curling plum aphid,
Brachycaudus helichrysi; (c) rosy leaf-curling aphid,
Dysaphis devecta; (d) rosy apple aphid, Dysaphis
plantaginea; (e) mealy plum aphid, Hyalopterus
pruni; (f) apple/grass aphid, Rhopalosiphum
insertum.
The green apple aphid is associated mainly with
apple but will also colonize pear, quince and
various other trees and shrubs in the family
Rosaceae, including ornamentals. Although
often common, and causing slight leaf curl, it is
usually of importance only on young host plants.
The winter is passed in the egg stage on the
bark of the young shoots. The eggs hatch from
April onwards and ant-attended colonies de-
velop quickly, the aphids clustering tightly to-
gether on the underside of leaves and along
the new shoots. Winged migrants produced in
June spread infestations. Wingless males and fe-
males are produced in the autumn prior to the
deposition of winter eggs by oviparae. Apterous
females (1.3-2.2 mm long) are bright green to
yellowish-green with moderately long, black or
dark brown siphunculi and a finger-like, tapered
cauda (Fig. 191a).
NOTE Several other members of this genus are
associated with cultivated plants, including: Aphis
craccivora Koch (cowpea aphid), a shiny black aphid
infesting herbage legumes and ornamental legumes;
A. lambersi (Borner) (permanent carrot aphid), a
black to greenish-black aphid on carrot; A. schneideri
(Borner) (permanent currant aphid), a dark green,
wax-coated aphid on red currant and black currant;
and A. triglochinis Theobald (red currant/arrowgrass
aphid), a brownish-green species overwintering on red
currant and, less frequently, black currant.
Aulacorthum solani (Kaltenbach)
Glasshouse & potato aphid
This extremely polyphagous aphid is a com-
mon glasshouse species, where it infests various
vegetable and ornamental plants. It is often also
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