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Macrosiphum weberi

Devil's-bit aphid

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

Identification & Distribution

Adult apterae of Macrosiphum weberi are plump oval to elliptical in shape (cf. Macrosiphum rosae, which are spindle-shaped). They are usually coloured dark violet-red, but Holman (1972) reports occasional green or yellow individuals and a green form is present in Scotland (see Stroyan, 1955, and images presented here). Antennal segments I & II are black, III & IV are mainly pale, segment V is similar but darker and segment VI is black apart from the tip of the terminal process which may be whitish. The abdomen often has moderate to quite large black marginal sclerites on segments I-IV and VII, as well as large black ante- and post-siphuncular sclerites. Spino-pleural sclerites are also sometimes present, most often on abdominal segments VII & VIII. The femora have their distal thirds black. The siphunculi are entirely black (cf. Macrosiphum euphorbiae, which has pale siphunculi which may be brownish distally). The siphunculi are less than 0.33 times the body length, abruptly tapering near the base and quite slender, about equal in thickness to the hind tibiae at midlength (cf. Macrosiphum rosae, whose siphunculi are usually longer than 0.33 times the body length, and thicker than the hind tibiae at midlength). The cauda is yellowish-white and at least 0.5 times the siphuncular length, without any basal constriction.

Both images above copyright Alan Watson Featherstone all rights reserved.

The alate Macrosiphum weberi is similar to the aptera except that the head and thorax are black, antennal segment III is dark due to secondary rhinaria along most of its length, and the femora have their distal halves black. The alate abdomen has large dark grey to black lateral sclerites, narrow spinal sclerites and ante- and postsiphuncular sclerites.

The clarified slide mounts below are of adult viviparous female Macrosiphum weberi : wingless, and winged.

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

The principal host of Macrosiphum weberi is devil's-bit scabious, Succisa pratensis, but it has also been recorded on two species of Scabiosa. There is no host alternation, and sexuales with alate males develop in autumn. Colonies of Macrosiphum weberi are usually attended by ants. The devil's bit aphid has been recorded from much of Europe, but mainly seems to frequent alpine areas.

 

Biology & Ecology

Ant attendance

One of the most interesting things about Macrosiphum weberi is that it is one of a very few members of the Macrosiphini that is attended by ants. The other member of the Macrosiphini found regularly on Succisa, Macrosiphum rosae, is very rarely (if ever) attended by ants.

Image above copyright Alan Watson Featherstone all rights reserved.

The Macrosiphum weberi shown here from Scotland were attended by Myrmica ruginodis, a species found across the northern Palaearctic region, at higher altitudes than the common red ant Myrmica rubra.

Image above copyright Alan Watson Featherstone all rights reserved.

Heie (2009) commented that the long siphunculi of Macrosiphini may interfere with honeydew gathering by ants, and anyway the release of warning pheromones from the siphunculi is less important for aphids that have ant protection.

Image above copyright Alan Watson Featherstone all rights reserved.

Given the above, one might expect Macrosiphum weberi to have somewhat shorter siphunculi than other Macrosiphum species, and this is true in relation to Macrosiphum rosae - but not to several other non-attended Macrosiphum species.

 

Natural enemies

Ricci & Ponti (2005) reported the coccinellid Ceratomegilla notata as a predator of Macrosiphum weberi in natural pastures in the mountain environments of the Northern Italian Alps. Other prey of this coccinellid included Megoura viciae, Uroleucon jaceae, Uroleucon cichorii and Cavariella theobaldi.

Image above copyright Hectonichus under a Creative Commons Attribution 4.0 International License.

 

Other aphids on the same host

Macrosiphum weberi occurs on 1 species of Succisa (Succisa pratensis).

Macrosiphum weberi occurs on 2 species of scabious, Scabiosa (Scabiosa atropurpurea, Scabiosa columbaria)

Acknowledgements

We are very grateful to Alan Watson Featherstone for his photos of this aphid from Scotland.

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 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

References

  • Heie, O.E. (2009). Aphid mysteries not yet solved /Hemiptera:Aphidomorpha/ Aphids and other hemipterous insects 15, 31-48. Full text

  • Holman, J. (1972). Description of Macrosiphum knautiae sp.n., with notes on the taxonomy of the M. rosae group. (Homoptera, Aphididae). Acta Entomologica Bohemoslovaca. 69(3), 175-185.

  • Ricci, C. & Ponti, L. (2005). Seasonal food of Ceratomegilla notata (Coleoptera: Coccinellidae) in mountain environments of Northern Italian Alps. European Journal of Entomology 102, 527-530. Full text

  • Stroyan, H.L.G. (1955). Recent additions to the British aphid fauna. Part II. Transactions of the Royal Entomological Society of London 106(7), 283-340.