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Gooseberry-sowthistle aphidIdentification & Distribution Biology & Ecology Damage & Control
Identification & Distribution:Adult apterae of Hyperomyzus pallidus are opaque yellowish white or greenish. The legs and antennae are pale with dark apices to the segments. The siphunculi are dark-tipped and are 3-5 times longer than the maximum width of their swollen part. The swollen part is 1.6-2.4 times the minimum width of the basal part. The body length of adult Hyperomyzus pallidus apterae is 2.3-3.5 mm.
The secondary rhinaria on antennal segment III of the aptera are more or less evenly distributed along the length of the segment (compare Hyperomyzus lactucae where they are clustered towards the base of the segment). The hairs on antennal segment III are short, only about a quarter of the basal diameter of that segment (compare Hyperomyzus lactucae where they are about a half of the basal diameter of that segment).
The clarified slide mounts below are of adult viviparous female Hyperomyzus pallidus: wingless, and winged.
The alate has a more-or-less solid black dorsal abdominal patch and blackish siphunculi. It has 50-75 secondary rhinaria on antennal segment three, 15-28 on segment IV and 0-9 on segment V.
The gooseberry-sowthistle aphid host alternates from the young leaves of gooseberry (Ribes uva-crispa) to the lower leaves of sowthistles (Sonchus spp.). Sexual forms occur in autumn. Hyperomyzus pallidus is found throughout Europe and in western Siberia, and has been introduced to North America.
Biology & Ecology:
There is very little in the literature about the biology and ecology of Hyperomyzus pallidus on either the primary or secondary hosts.
We have found them on gooseberry, the primary host, in May in mixed colonies with the currant aphid Nasonovia ribisnigri.
The picture above shows a single Hyperomyzus pallidus (centre screen) surrounded by a colony of developing fourth instar future alate Nasonovia ribisnigri.
On its secondary host, sow-thistle, it is often found in mixed colonies with Hyperomyzus lactucae. Hyperomyzus pallidus prefers the undersides of lower leaves, often closer to the ground, whilst Hyperomyzus lactucae prefers the upper parts of stems and flowers.
Damage and control
Hyperomyzus pallidus is usually considered to be a relatively minor pest of gooseberry. Spring infestations on young shoots can cause stunting and leaf curl, as well as a characteristic yellow vein-banding of the leaves.