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Aphidinae : Macrosiphini : Sitobion berkemiae
 

 

Sitobion berkemiae

Bear willow aphid

On this page: Identification & Distribution Other aphids on the same host

Identification & Distribution

Adult apterae of Sitobion berkemiae have a deep green abdomen, a brown head and prothorax and black sclerotic siphunculi. Their antennae are black, six segmented, with a terminal process about 6.6 times as long as the base of antennal segment VI. The apical rostral segment has 4-6 accessory hairs. The dorsum is largely membranous apart from darkened postsiphuncular sclerites. The femora are greenish basally and black distally; the tibiae and tarsi are jet black. The tapering siphunculi are about 1.6 times the length of the cauda. They have a small but distinct flange, and reticulation on the distal 0.32-0.44 of their length (cf. Sitobion berchemiae in China, which have reticulation on the distal 0.25-0.33 of their siphunculi). The cauda is pale yellow-green. The body length of adult Sitobion berkemiae apterae is 1.3-1.8 mm.

Note: Sitobion berkemiae was first described as Acyrthosiphon berkemiae by Shinji (1941), then redescribed as Macrosiphum berkemiae by Miyakazi (1980), before being reassigned to Sitobion by Blackman & Eastop (1984). Sitobion berkemiae may be a synonym of the Chinese species Sitobion berchemiae Takahashi.

Image above by permission, copyright Akihide Koguchi, all rights reserved.

We can find no description of the alate vivipara of Sitobion berkemiae, but it is likely to be similarly coloured to the aptera apart from increased sclerotization on the head and thorax, and possibly black abdominal markings.

Image above by permission, copyright Akihide Koguchi, all rights reserved.

Immatures (see picture above) are coloured as the adult aptera, except that immature alatae (and probably immature apterae of instars 1-III) have only the distal part of their siphunculi dark.

Image above by permission, copyright Akihide Koguchi, all rights reserved.

The only known host of Sitobion berkemiae is bear willow (Berchemia racemosa) in the buckthorn family (Rhamnaceae). They feed along the leaf veins (see picture above). The life cycle of the aphid is unknown. Sitobion berkemiae is only known from Japan.

 

Other aphids on the same host

Sitobion berkemiae has been recorded on 1 species of Berchemia (Berchemia racemosa).

Blackman & Eastop list 2 species of aphid as feeding on bear willow (Berchemia racemosa) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 1 as occurring in Britain (Show British list).

Acknowledgements

We are especially grateful to Akihide Koguchi for allowing us to reproduce the image of Sitobion berkemiae from his blog page, and to Daisuke Sasaki who confirmed the identification.

We have used the keys and species accounts from Roger Blackman & Victor Eastop in Aphids on Worlds Plants, supplemented with measurements from the photos. 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

References

  • Miyakazi, M. (1980). Redescription of Macrosiphum berkemiae. Akitu 30, 1-4.

  • Shinji, O. (1941). [Monograph of Japanese Aphididae], Shinkyo Sha Shoin, Tokyo 1215 pp.