Aphis ruborum

Identification & Distribution:

Aphis ruborum apterae (see first picture below) are commonly dark blue-green in spring and pale yellow-green in summer. Dwarf apterae (0.8-1.0 mm) occur in late summer. The abdominal dorsum is mostly pale and membranous. The siphunculi are pale but with dusky bases and apices, and 1.1-2 times the length of the cauda. The antennae and legs are pale. The body length of Aphis ruborum apterae usually varies from 1.1-2.2 mm.

For further assistance in identifying Aphis ruborum see INRA.

The small bramble aphid does not host alternate. Aphis ruborum feeds on blackberry (Rubus fruticosus). It is also found on loganberry and rarely on strawberry. In early summer it lives in dense colonies, is ant attended and causes leaf curl. In late summer dwarf apterae may be found living singly on the underside of the leaf between the veins. Sexual forms occur in autumn. Aphis ruborum is widely distributed through Europe into North Africa and central Asia.

Biology & Ecology:

Life cycle

In spring dense colonies of Aphis ruborum develop on the young shoots of blackberry (Rubus fruticosus agg.). The darker green forms seem to occur mainly in spring, but this is by no means invariant. Both colour forms can be found for much of the summer and sometimes even together in the same colony.

Examination of a large number of our photos suggests that the variation in the shade of green of the small bramble aphid is related to maintaining crypsis on the host plant, as the plant stem and leaf colour varies through the year.

Hille Ris Lambers (1950) notes that numerous alates appear in the second generation of the year. These disperse to other bramble bushes. Later in the year they can be found under leaves, in flowers (see first picture below of aphids on flower stems) and on developing fruits (see second picture below of aphids on developing berries).

Aphis ruborum spends the winter as eggs at the base of buds.

Ant attendance

Aphis ruborum is nearly always attended by ants, in the first picture below by a Lasius species, in the second by Formica rufa.

The pictures below show Aphis ruborum being attended by Myrmica ants (first), and an attendant Myrmica ant in alcohol (second).

Natural enemies

The recorded parasitoid spectrum of Aphis ruborum in the West Palaearctic is rich (Havelka et al., 2012). It is composed of Aphidius colemani, Aphidius matricariae, Binodoxys acalephae, Binodoxys angelicae, Ephedrus persicae, Lipolexis gracilis, Lysiphlebus confusus, Lysiphlebus fabarum and Praon abjectum, and supplemented by the introduction of Lysiphlebus testaceipes. Surprisingly we have only once found large numbers of a colony of the bramble aphid parasitized (see picture below).

Possibly their attending ants generally keep parasitoids away from the aphids.

Of the predators, syrphid larvae seem to be the most common, two different species of which are shown below. Using Rotheray (1984) we have provisionally identified the first as Platycheirus scutatus, a species associated with a wide range of ground layer aphids. The second is most likely a Baccha sp. found on low growing herbaceous plants, particularly those in shady conditions.

Aphis ruborum are also predated by the larvae of various Cecidomyiidae. We have yet to find larvae of these, but we have found cecidomyiid eggs either laid directly on to aphids or in their vicinity (see pictures below).

Other aphids on same host:

Blackman & Eastop list 10 species of aphid as feeding on blackberry (Rubus fruticosus) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 7 as occurring in Britain (Show British list).

Loxdale & Brookes (1989) found that electrophoresis provided an excellent way to differentiate early instars of four of these species, Amphorophora rubi, Macrosiphum funestum, Sitobion fragariae and Aphis ruborum.

Beneficial effects:

Many of the parasitoids recorded for Aphis ruborum are important parasitoids of aphids of agricultural importance. Havelka et al. (2012) suggest that Aphis ruborum constitutes a valuable parasitoid reservoir both in Europe and the Americas.

Acknowledgements We especially thank Warnham Common Nature Reserve for their kind assistance, and permission to sample. Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made 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  Havelka, J. et al. (2012). Review and key to the world parasitoids (Hymenoptera: Braconidae: Aphidiinae) of Aphis ruborum (Hemiptera: Aphididae) and its role as a host reservoir. Annals of the Entomological Society of America 105(3), 386-394. Full text  Hille Ris Lambers, D. (1950). The Rubus aphids of the Netherlands. Tijdschrift over Plantenziekten 56(3), 253-261. Abstract  Rotheray, G.E. (1984). Colour guide to hoverfly larvae (Diptera, Syrphidae) in Britain and Europe. Dipterists Digest No. 9. Derek Whiteley, Sheffield. Full text