Hyperomyzus pallidus

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 clarified slide mounts below are of adult viviparous female Hyperomyzus pallidus: wingless (from Sonchus), and winged.

Micrographs of clarified mounts by permission of Roger Blackman, copyright AWP all rights reserved.

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.

Other aphids on same host:

Primary host

Blackman & Eastop list 21 species of aphid as feeding on gooseberry (Ribes uva-crispa) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 16 as occurring in Britain (Show British list).

Secondary hosts

• Blackman & Eastop list 36 species of aphid as feeding on common sowthistle (Sonchus oleraceus) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 24 as occurring in Britain (Show British list).

• Blackman & Eastop list 23 species of aphid as feeding on field sow thistle (Sonchus arvensis) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 18 as occurring in Britain (Show British list).

• Blackman & Eastop list 24 species of aphid as feeding on prickly sowthistle (Sonchus asper) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 19 as occurring in Britain (Show British list).

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.

Acknowledgements We especially thank Plumpton College for their kind assistance, and permission to sample. Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994) and Blackman & Eastop (2006) supplemented with Blackman (1974), Stroyan (1977), Stroyan (1984), Blackman & Eastop (1984), Heie (1980-1995), Dixon & Thieme (2007) and Blackman (2010). We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

Useful weblinks