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Genus Schizaphis

Grass aphids

Species Overview: Schizaphis   Schizaphis graminum  Schizaphis scirpi 

Schizaphis [Aphidini]

Schizaphis are small to medium sized aphids, ovate to somewhat elongate in shape. The dorsal body cuticle is colourless to smoky and more or less reticulate, sometimes with a transverse dark band across abdominal tergite 8. The siphunculi are cylindrical to slightly tapering. The cauda is blunt finger shaped, from about half as long as, to slightly longer than, the siphunculi. The rostrum is short, not reaching beyond the middle coxae. The forewing of the alate has the median vein only once branched.

This genus has about 40 species, of which about half of which live all year on grasses (Poaceae). Most of the rest belong to the subgenus Paraschizaphis and live on on sedges (Cyperaceae) and bulrushes (Typhaceae). A few mainly Asian species host alternate, overwintering as eggs on pear (Pyrus) or apple (Malus). More than half the species are European, and the others live in Middle East, Asia, Africa and North America.

 

Schizaphis graminum (Greenbug aphid)

Adult apterae of Schizaphis graminum are small and elongate-oval. The head and prothorax is yellowish or greenish straw-coloured. The rest of the thorax and the abdomen are yellowish green to bluish green with a noticeable darker green spinal stripe. The antennae are uniformly dusky. The siphunculi are pale with slightly flared and darkened tips. The body length of Schizaphis graminum aptera is 1.3 to 2.1 mm.

 

First image: Kent Loeffler (Public domain).   Second image: Alton N. Sparks (Creative Common Attribution 3.0 Unported license)

Schizaphis graminum alatae have a brownish-yellow head and prothorax, black thoracic lobes and a yellowish green to dark green abdomen.

The preferred hosts are grasses and cereals, where Schizaphis graminum can be a major pest. It causes severe feeding damage - initially yellow or red leaf spots which can lead to leaf and root death. It also transmits several plant viruses including barley yellow dwarf virus. Schizaphis graminum develops sexual forms in cold temperate climates, where overwintering in the egg stage occurs predominantly on Poa pratensis, but it continues to reproduce parthenogenetically wherever the climate allows. Schizaphis graminum is not ant attended.

This aphid is of Palaearctic origin, but is now widely distributed in southern Europe, Middle East, Central and South Asia, Africa and the Americas. Despite the fact that two alatae trapped in UK had identical DNA sequences to the sorghum-adapted form in the USA, there are no records from field crops in northern Europe. We discuss why Schizaphis graminum has failed to establish itself in Western Europe in our rare aphids page. 

 

Schizaphis scirpi (Bulrush aphid)

Apterae of Schizaphis scirpi are shiny dark bronze-brown to reddish brown or blackish. The third segment of the antenna is dark with long fine hairs up to 3-4 times longer than the basal diameter of the segment. The longest hairs on abdominal tergite 3 are 0.10-0.13 mm long. The siphunculi are about twice as long as the cauda. The body length of Schizaphis scirpi apterae is 1.5-2.8 mm.

 

Guest images copyright Sandy Rae , all rights reserved

Schizaphis scirpi alatae have 7-16 secondary rhinaria on the third antennal segment, 0-8 on the fourth, and 0-1 on the fifth.

The bulrush aphid lives in ant-attended colonies at the leaf-bases of bulrushes (Typha spp.) and bur-reed (Sparganium spp.). They also occur on sedges (Carex, Eriophorum, Scirpus) and sometimes on other water plants. European populations on cottongrass (Eriophorum spp.) are considered to be a subspecies, Schizaphis scirpi ssp. eriophori They do not host alternate. Oviparae and winged males develop in the autumn. Schizaphis scirpi are found throughout Europe, and in south-west Asia.

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Acknowledgements

We have made provisional 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 sp 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).

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