Brachycaudus cardui

Identification & Distribution:

Brachycaudus cardui apterae (see first picture below) are brownish-yellow, pale green or brown, 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 Brachycaudus cardui rostrum is long and reaches the hind coxae. 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. (cf. the short-haired Brachycaudus lateralis. for which 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. ) Their siphunculi are black, thick and cylindrical and 1.7-3.4 times the length of their cauda. The body length of apterae is 1.8-2.4 mm.

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

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

In continental Europe Brachycaudus cardui host alternates between various Prunus species, mainly cherry, plum and apricot, and various wild and cultivated daisies (Asteraceae) especially thistle (Carduus and Cirsium spp.) and borage (Boraginaceae). In Britain it seems to live all year round on Asteraceae. Infested leaves undergo severe curling. Dense colonies occur at the base of flower heads and on the leaves. A return migration to primary hosts occurs in autumn. The plum-thistle aphid is found throughout Britain and Europe as well as in Asia, north Africa and North America.

Other aphids on same host:

Primary hosts

Brachycaudus cardui has been recorded on at least 14 Prunus species, ans there are about 72 species of aphids which feed on plants in the genus Prunus worldwide (Show World list) of which 24 have been recorded in Britain (Show British list).

• Of the 16 species of aphid on sweet cherry (Prunus avium) (Show World list) Baker (2015) lists 12 as occurring in Britain (Show British list).

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

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

• Blackman & Eastop list 21 species of aphid as feeding on apricot (Prunus armeniaca) worldwide, and provide formal identification keys (Show World list).

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

Secondary hosts

• Brachycaudus cardui has been recorded on 18 Carduus species.

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

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

• 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) (Show World list). Baker (2015) lists 22 as occurring in Britain (Show British list).

Acknowledgements Our particular thanks to Roger Blackman for images of his clarified slide mounts. 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

 

Identification requests Alan Outen, 03 June 2014, Re: Aphid hunting Today in Shefford, Beds I found a species on Oxford Ragwort (Senecio squalidus) but which was clearly not Aphis jacobaeae. Using the on-line Blackman and Eastop key it suggests four options: S. squalidus Brachycaudus cardui, helichrysi, lateralis; Macrosiphum euphorbiae, and I came down to Brachycaudus cardui, which I hope is correct. Image(s) copyright Alan Outen, all rights reserved.     Bob, InfluentialPoints: Almost certainly Brachycaudus cardui. Can't distinguish B. lateralis from B. cardui in photos. B. lateralis is basically a short haired version of B. cardui. But looking at Blackman, they may be one and the same species, so for photos I'll just stick to B. cardui! I have now looked at the hairs on the Brachycaudus under the stereo-binoc and these are certainly right for B. cardui.