Biology Reference
In-Depth Information
158
159
158
Colony of poplar/buttercup aphid (
Thecabius affinis
).
159
Gall of poplar/buttercup aphid (
Thecabius affinis
)
on
Populus
.
Thecabius affinis
(Kaltenbach) (
158-159
)
syn.
T. ranunculi
(Kaltenbach)
Poplar/buttercup aphid
Generally common on black poplar (
Populus nigra
) and,
less frequently, white poplar (
P. alba
'Pyramidalis'). The
summer forms infest the roots of buttercups
(
Ranunculus
), primarily creeping buttercup (
R. repens
).
Eurasiatic. Widespread in Europe.
DAMAGE
Poplar:
galls affect the development of new shoots,
disfiguring host plants; however, attacks on established
trees are of little or no consequence.
Buttercup:
heavy
infestations on the roots produce unsightly masses of
white wax and reduce the vigour of host plants;
however, attacks on cultivated species are uncommon
and rarely important.
Thecabius auriculae
(Murray)
Auricula root aphid
This species infests the roots of auricula (
Primula
auricula
) and certain other related plants. The aphids
feed on the roots, and are particularly damaging on
potted plants and on those growing in greenhouses or
under other protection. The aphids, which occur on the
roots throughout the year, are small (1.3-1.5 mm long),
pale yellowish white or pale greenish white, with
brownish legs, and are coated with white mealy wax.
Winged forms, which are larger (2.5 mm long) and
mainly brown to green, also occur. The leaves of
infested plants turn yellow, and may become mottled
and distorted, with considerable quantities of 'wool'
accumulating around the collar and amongst the root
system. Severely affected plants may wilt and die.
DESCRIPTION
Apterous female [on poplar]:
4.0-4.5 mm long; body
light green to greyish green, and coated with white
waxy powder; head, antennae and legs dark brown; legs
short and robust.
Alate [ex: poplar]:
2.6-3.0 mm long;
mainly blackish brown, with a green to purplish-green
abdomen; legs long and thin.
LIFE HISTORY
Eggs overwinter on poplar trees and hatch in the spring.
Wingless aphids then develop within light green,
yellowish-green, pouch-like galls, each formed from a
folded leaf. After a further generation of wingless
aphids, winged forms are produced; these migrate from
July onwards to the roots of buttercups. Subterranean
colonies of wingless aphids then develop on these
summer hosts, with winged forms appearing in the
autumn and returning to poplar in October and
November.
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