Brachycaudus tragopogonis

Identification & Distribution:

Adult apterae of Brachycaudus tragopogonis (see first picture below) are shining grey-brown to dark brown, although a dense colony appears black. The cross bands are often divided spinally as well as intersegmentally into paired pleural patches. The siphunculi are 0.05-0.06 times as long as the body length and 1.2-1.5 times as long as the cauda. The cauda is helmet-shaped. The body length of Brachycaudus tragopogonis apterae is 1.4-2.3 mm.

The alate viviparous female (see second picture above) has some membranous intersegmental stripes or windows in the dorsal sclerotic area, and abdominal segment 4 has paired ventral spots much smaller than those on segments 5 and 6. The extent of dorsal abdominal sclerotization on both the aptera and the alate is variable. Some are rather heavily sclerotized, whilst others are less so - especially anteriorly - see pictures of adult apterae in alcohol below.

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

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

Brachycaudus tragopogonis lives all year round on the stem and leaves of Tragopogon (goatsbeard) species with no host alternation. Oviparae and winged males appear in autumn. Brachycaudus tragopogonis is found in southern Britain and over much of Europe, and has been introduced to South America.

Biology & Ecology:

We have found this species in Britain several times on naturalized purple salsify (Tragopogon porrifolius) (see picture below), but not so far on any of the native Tragopogon species.

The picture below shows a heavily sclerotized adult aptera of Brachycaudus tragopogonis.

In some years quite large populations have been found on the purple salsify at Rye Harbour nature reserve in East Sussex. One of the aphids in the picture below is very lightly sclerotized.

Brachycaudus tragopogonis adults often have a circle of white wax around their posteriors, much like Brachycaudus lychnidis.

Ant attendance

Brachycaudus tragopogonis colonies produce copious amounts of honeydew (see picture below).

Not surprisingly they are frequently attended by ants consuming the sugar-rich liquid, as in the colony below.

Ozdemir (2008) recorded the ant species Formica glauca, Plagiolepis pallescens and Lasius alienus attending Brachycaudus tragopogonis in Ankara Province in Turkey.

Other aphids on same host:

Blackman & Eastop list 24 species of aphid as feeding on goatsbeard or salsify (Tragopogon species) worldwide, and provide formal identification keys.

Of those aphid species, Baker (2015) lists 18 as occurring in Britain: Aphis craccivora, Aphis fabae, Aphis gossypii, Aphis nasturtii, Aphis spiraecola, Brachycaudus cardui, Brachycaudus helichrysi, Brachycaudus tragopogonis, Hyperomyzus lactucae, Macrosiphum euphorbiae, Myzus persicae, Protaphis terricola, Smynthurodes betae, Trama caudata, Trama troglodytes, Uroleucon cirsii, Uroleucon erigeronense and Uroleucon jaceae.

Acknowledgements We especially thank Rye Harbour Nature Reserve for their kind assistance, and permission to sample. 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

References  Ozdemir, I. et al. (1997). Investigations of the associated between aphids and ants on wild plants in Ankara Province, Turkey. Mun. Ent. Zool. 3(2), 606-613. Full text