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Gooseberry-sowthistle aphidOn this page: Identification & Distribution Biology & Ecology Damage & Control
Identification & Distribution:Adult apterae of Hyperomyzus pallidus are opaque greenish or yellowish white (see first picture below). In our experience they are much paler on the secondary host (see second picture below) than on the primary host. The legs and antennae are pale with dark apices to the segments. The secondary rhinaria on antennal segment III of the aptera are more or less evenly distributed along the length of the segment (cf. 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 (cf. Hyperomyzus lactucae where they are about a half of the basal diameter of that segment).The siphunculi are dusky-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 alate (see picture below) has blackish siphunculi and a more-or-less solid black dorsal abdominal patch (cf. Hyperomyzus lactucae which has a rather broken (fenestrated) central dark patch on the upper surface of the abdomen). It has 50-75 secondary rhinaria on antennal segment III, 15-28 on segment IV and 0-9 on segment V.
The pictures below show an adult aptera (from the secondary host, Sonchus) and an alate of Hyperomyzus pallidus in alcohol.
The clarified slide mounts below are of adult viviparous female Hyperomyzus pallidus: wingless (from Sonchus), and winged.
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 rather little in the literature about the biology and ecology of Hyperomyzus pallidus on either the primary or secondary hosts. We have found this aphid on gooseberry, the primary host, in May in mixed colonies with the currant aphid Nasonovia ribisnigri.
The picture above shows an adult aptera on gooseberry, whilst the picture below shows a single Hyperomyzus pallidus (image centre) surrounded by a colony of developing fourth instar future alate Nasonovia ribisnigri.
We have also found Hyperomyzus pallidus commonly on its secondary host, sow-thistle, late in the year in September and October.
It prefers the undersides of lower leaves, often closer to the ground, whilst Hyperomyzus lactucae prefers the upper parts of stems and flowers.
Most of the aphids in October were destined to be alatae for the return migration to the primary host, such as the fourth instar future alate shown in the picture above.
This shows an alate just prior to its return flight.
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.