Brachycaudus lateralis

Identification & Distribution:

Brachycaudus lateralis apterae (see first picture below) are green or reddish, with separate cross bars on thoracic segments, a large shining black spot situated dorsally on the abdomen and 2 or 3 black stripes at the tip. The rostrum is long and reaches the hind coxae. The longest hairs on abdominal tergite 8 are 20-61 µm long, and the longest hairs on the hind femur are 10-25 μm long (cf. the closely related Brachycaudus cardui for which the longest hairs on abdominal tergite 8 are 85-110 μm long, and the longest hairs on the hind femur are 40-80 μm long). Their siphunculi are black, thick and cylindrical and 2.3-3.4 times the length of the cauda. The body length of apterae of Brachycaudus lateralis is 1.6-2.6 mm.

Note: the results of recent DNA studies suggest that Brachycaudus lateralis should only be accorded subspecific status to Brachycaudus cardui.

The alate female (not pictured) has a dorsal patch irregularly bordered, and partly broken into crossbars and smaller sclerites. There are 18-35 secondary rhinaria on antennal segment III, and none on segment IV. Immatures (see second picture above) often have reddish patches on a greenish background. The pictures below are micrographs of Brachycaudus lateralis in alcohol. The first is an adult aptera whilst the second shows the very short hairs on the femur.

Brachycaudus lateralis is usually found close to the ground on the stems and leaves of numerous Asteraceae, including chamomile (Anthemis), thistles (Carduus, Cirsium) and ragworts and groundsels (Senecio), where they are usually attended by ants which tent over the colony with soil particles. Brachycaudus lateralis usually remains on Asteraceae all year, although it has been recorded host alternating to plum (Prunus). Brachycaudus lateralis is found over most of Europe.

Biology & Ecology:

Most work on Brachycaudus lateralis has been focused upon whether it can be regarded as 'good' species distinct from Brachycaudus cardui. Remaudière & Remaudière (1997) and Heie (1992) and others regard them as two separate species. Andreev (2004) and others regard Brachycaudus lateralis as a subspecies of Brachycaudus cardui, while Eastop & Hille Ris Lambers (1976) treat Brachycaudus lateralis as a synonym of Brachycaudus cardui. More recently Coeur d'acier (2007) using molecular techniques found all their Brachycaudus cardui and Brachycaudus lateralis samples clustered together in a highly supported clade showing very small intragroup genetic distance. Moreover, the two 'species' did not form two separate clades, indicating no genetic difference. Jousselin et al. (2009), Jousselin et al. (2010) found a lack of symbiont DNA divergence between aphid specimens identified as belonging to these two 'species, and concluded that the two morphospecies, Brachycaudus cardui and Brachycaudus lateralis, may actually correspond to a single biological species.

All the colonies of Brachycaudus lateralis that we have found have been attended by ants, often tented with earth particles. This was the case for the colony on spear thistle (Cirsium vulgare) shown below.

Lasius niger was usually the species of ant attending Brachycaudus lateralis. The picture below shows this species of ant attending on lesser burdock (Arctium minus).

Colonies of Brachycaudus aphids on thistles are often heavily parasitized especially by Lysiphlebus fabarum.

Other aphids on same host:

Primary hosts

There are unconfirmed reports of Brachycaudus lateralis on 2 Prunus species: Prunus domestica and Prunus spinosa.

• Blackman & Eastop list 23 species of aphid as feeding on common or European plum (Prunus domestica) worldwide, and provide formal identification keys.

  Of those aphid species, Baker (2015) lists 17 as occurring in Britain: Aphis craccivora, Aphis fabae, Aphis gossypii Brachycaudus amygdalinus, Brachycaudus cardui, Brachycaudus helichrysi, Brachycaudus persicae, Hyalopterus pruni, Macrosiphum euphorbiae, Myzus lythri, Myzus ornatus, Myzus persicae, Nearctaphis bakeri, Rhopalosiphum nymphaeae, Rhopalosiphum padi and Rhopalosiphum rufiabdominale.

• Blackman & Eastop list 13 species of aphid as feeding on blackthorn (=sloe, Prunus spinosa) worldwide, and provide formal identification keys.

  Of those aphid species, Baker (2015) lists 9 as occurring in Britain: Aphis pomi, Brachycaudus cardui, Brachycaudus helichrysi, Brachycaudus persicae, Brachycaudus prunifex, Hyalopterus pruni, Rhopalosiphum nymphaeae and Rhopalosiphum padi.

Secondary hosts

• Brachycaudus lateralis has been recorded on at least 6 Senecio species.

  Blackman & Eastop list 16 species of aphid as feeding on ragwort (=Stinking willie, Senecio jacobaea, Jacobaea vulgaris) worldwide, and provide formal identification keys.

  Of those aphid species, Baker (2015) lists 12 as occurring in Britain: Aphis fabae, Aphis jacobaeae, Aphis nasturtii, Aulacorthum solani, Brachycaudus cardui, Brachycaudus helichrysi, Brachycaudus lateralis, Eriosoma patchiae, Macrosiphum euphorbiae, Myzus persicae, Protaphis terricola and Uroleucon sonchi.

• Brachycaudus lateralis has been recorded on 2 Carduus species (C. pycnocephalus and C. tenuiflorus).

  Aside from a few polyphagous aphids, Blackman & Eastop list 29 aphid species as feeding on Carduus thistles worldwide, and provide formal identification keys.

  Of those aphid species, Baker (2015) lists 13 as occurring in Britain: Aphis fabae, Aphis gossypii, Aphis solanella, Brachycaudus cardui, Brachycaudus helichrysi, Brachycaudus lateralis, Capitophorus carduinus, Capitophorus elaeagni, Pemphigus bursarius, Protrama radicis, Trama troglodytes, Uroleucon aeneum and Uroleucon cichorii.

• Brachycaudus lateralis has been recorded on unspecified Cirsium species.

  Blackman & Eastop list about 55 species of aphids as feeding on Cirsium species worldwide, and provides formal identification keys for aphids on Cirsium.

  Of the 36 species on creeping thistle (Cirsium arvense) Baker (2015) lists 41 as occurring in Britain: Aphis fabae cirsiiacanthoidis Aphis gossypii, Aphis nasturtii, Aphis solanella, Aulacorthum solani, Brachycaudus cardui, Brachycaudus helichrysi, Capitophorus carduinus, Capitophorus elaeagni, Capitophorus gynoxanthus, Dysaphis lappae cirsii, Hyperomyzus lactucae, Macrosiphum euphorbiae, Myzus cymbalariae, Myzus persicae, Protaphis terricola, Protrama radicis, Smynthurodes betae, Trama troglodytes, Uroleucon aeneum, Uroleucon cirsii, and Uroleucon jaceae.

• Whilst Brachycaudus lateralis has yet to be recorded on Anthemis arvensis, it has been recorded on Anthemis cotula and Anthemis tinctoria.

  Blackman & Eastop list 23 species of aphid as feeding on those two species.

  Of those aphid species, Baker (2015) lists 19 as occurring in Britain: Aphis fabae, Aphis nasturtii, Aphis spiraecola, Aphis vandergooti, Aphis gossypii, Aulacorthum solani, Brachycaudus cardui, Brachycaudus helichrysi, Brachycaudus lateralis, Macrosiphoniella abrotani, Macrosiphoniella millefolii, Macrosiphoniella tanacetaria, Macrosiphum euphorbiae, Myzus ornatus, Myzus persicae Pemphigus bursarius, Trama troglodytes, and Uroleucon jaceae.