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Aphidinae : Macrosiphini : Diuraphis tritici
 

 

Diuraphis tritici

Western wheatgrass aphid

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

Identification & Distribution

Adult apterae of Diuraphis tritici (see picture below) are pale yellowish-green, but that colour is obscured by a rather dense covering of fine white wax powder. Their siphunculi, cauda and legs are dusky. Their antennae are much shorter than the body. The rostrum extends to or past the second pair of coxae (cf. Diuraphis frequens, which has a short rostrum, not reaching the second pair of coxae). The apical rostral segment (RIV+V) is approximately 3 times as long as wide at base, with 2 accessory hairs; it is 0.9-1.15 times as long as the second hind tarsal segment (HTII) (cf. Diuraphis frequens, which has a relatively shorter RIV+V at only 0.5-0.75 times HTII). There is no supracaudal process on abdominal tergite VIII, and usually no marginal tubercles on abdominal tergites II-VI (cf. Diuraphis noxia, Diuraphis mexicana & Diuraphis muehlei, which have a supracaudal process on tergite VIII, and marginal tubercles on at least tergites III-V). The siphunculi are short, without an apical flange. The cauda is elongate, triangular with rounded apex, and with 4-6 lateral hairs. The body length of adult Diuraphis tritici apterae is 1.9-2.2 mm.

Note: Although the picture below appears to show that Diuraphis tritici has a denser whiter wax coating than Diuraphis frequens, this may not be a reliable character to distinguish the species. The degree of waxing of aphids tends to be very variable, depending on time since last moult, climate factors, degree of ant attendance and (we expect) predation.

Image copyright Frank Peairs, Colorado State University, Bugwood.org under a creative commons licence.

The alate Diuraphis tritici (not pictured) has a green abdomen. The head, thorax, most of antennae, and the cauda are black. The siphunculi are a little yellowish or brownish. The body is covered with white wax powder. The antennae are shorter than body, with 4-7 secondary rhinaria on segment III, 1-3 on IV and 0-1 on V. The wing veins are conspicuously darkened.

Diuraphis tritici lives in the curled leaves of grasses, especially western wheatgrass (Elymus smithi) and other Elymus species, and also sometimes on wheat (Triticum). Feeding damage is expressed as regular red or yellowish streaking on the green leaves. It is monoecious holocyclic with oviparae and apterous males in October. Diuraphis tritici are not attended by ants. It was first found and described in several western states of the USA, and more recently in Peru. It is also found in East Asia where it is may have originated, although most workers consider it a native American species.

 

Other aphids on the same host

Blackman & Eastop list 5 species of aphid as feeding on western wheatgrass (Elymus smithi) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists none as occurring in Britain (Show British list).

Blackman & Eastop list 60 species of aphid as feeding on 'common wheat' (Triticum aestivum) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 30 as occurring in Britain (Show British list).

 

Damage and control

Diuraphis tritici is not known to reach pest status on cereal crops, but there is concern regarding it's ability to interbreed with the Russian wheat aphid (Diuraphis noxia). Puterka (2017) found that Diuraphis tritici males readily mate with Diuraphis noxia females. The offspring were not as fit for survival as their parents, but their parthenogenetically-produced offspring damaged wheat and barley more than either parent.

Acknowledgements

We are grateful to Frank Peairs, Colorado State University, for making his picture of Diuraphis tritici available for use under a creative commons licence.

We have used the keys and species accounts of Gillette (1911) (as Brachycolus tritici) Miller et al. 2005 and Puterka et al. (2010) along with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors and those listed in the reference sections 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

  • Gillette, C.P. (1911). A new genus and four new species of Aphididae (Rhynch.) Entomological News 22(10), 440-444. Full text

  • Miller, G.L. et al. (2005). A systematic reappraisal of the genus Diuraphis Aizenberg (Hemiptera: Aphididae). Proc. Entomol. Soc. Wash. 107(3), 700-728. Full text

  • Puterka, G.J. et al. (2010). Host associations and incidence of Diuraphis spp. in the Rocky Mountain Region of the United States, and pictorial key for their identification. Journal of Economic Entomology 103(5), 1875-1885. Full text

  • Puterka, G.J. (2017). More virulent offspring result from hybridization of invasive aphid species, Diuraphis noxia (Hemiptera: Aphididae), with Diuraphis tritici endemic to the United States. Journal of Economic Entomology 110(2), 731-738. Full text