Schizaphis scirpi

Identification & Distribution:

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.

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 species) and bur-reed (Sparganium pecies). They also occur on sedges (Carex, Eriophorum, Scirpus) and sometimes on other water plants. European populations on cottongrass (Eriophorum pecies) 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.

Biology & Ecology:

There is very little published about the ecology of Schizaphis scirpi. The reddish colour of the leaf with the aphid colony below is most likely feeding damage caused by Schizaphis scirpi. A similar discoloration is caused by the pest species, Schizaphis graminum.

Guest image copyright Sandy Rae, all rights reserved.

The aphid colony below are coloured a more bronzy brown reflecting the colour variation in this species.

Guest image copyright Sandy Rae, all rights reserved.

There has been some work done on parasitoids of this species. Petrovic et al. (2009) reported Schizaphis scirpi as a host for the parasitoid Trioxys auctus. Tomanovic et al. (2012)pointed out that Schizaphis scirpi, along with other wetland aphid species, is an important alternative host for three beneficial parasitoid species, namely Lipolexis gracilis, Ephedrus plagiator and Diaretiella rapae. Since these aphids do not attack any cultivated plants, these parasitoids and their hosts have great potential for biocontrol.

Other aphids on same host:

• Schizaphis scirpi has been recorded from 7 Typha species.

  Blackman & Eastop list 23 species of aphid as feeding on bulrushes (Typha species) worldwide, and provide formal identification keys (Show World list).

  Of those aphid species, Baker (2015) lists 13 as occurring in Britain (Show British list).

• Schizaphis scirpi has been recorded from 1 Sparganium species Sparganium erectum.

  Blackman & Eastop list 3 species of aphid as feeding on bur-reed (Sparganium species) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 2 as occurring in Britain: (Show British list).

• Schizaphis scirpi has been recorded from 7 Carex species.

  Blackman & Eastop list about 110 species of aphids as feeding on sedges worldwide, and provide formal identification keys for aphids on Carex (Show World list).

  Of those, Baker (2015) lists 32 aphid species as occurring in Britain (Show British list).

• Schizaphis scirpi has been recorded from 3 Scirpus species (Scirpus cernuus, Scirpus maritimus, Scirpus sylvaticus).

  Blackman & Eastop list at least 27 species of aphids as feeding on club rush worldwide, and provide formal identification keys for aphids on Scirpus (Show World list).

  Of those, Baker (2015) lists 17 aphid species as occurring in Britain (Show British list).

• Schizaphis scirpi eriophori has been recorded from 2 Eriophorum species (Eriophorum angustifolium, Eriophorum vaginatum).

  Blackman & Eastop list 9 species of aphid as feeding on cottongrass (Eriophorum species) worldwide, and provide formal identification keys (Show World list).

  Of those aphid species, Baker (2015) lists all 9 as occurring in Britain (Show British list).