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Protrama radicis

Thistle-root aphid, Daisy-root aphid

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

Identification & Distribution:

Adult apterae of Protrama radicis are dirty-white to pale-yellow or pale brownish-green. Each segment of the dorsum has a transverse dark sclerotized bar (cf. Trama species  which have no dark bars on the dorsum of the aptera). The head and appendages are dark. The antennal terminal process of Protrama radicis is 0.33-0.69 times the length of the base of the sixth antennal segment. The hind tarsus is 0.72-0.87 times the length of the hind tibia (cf. Protrama flavescens where the hind tarsus is only 0.59-0.70 times as long as the hind tibia). Siphunculi are present as pores placed on small brown cones. The body length of the adult aptera is 2.5-3.4 mm. The immatures are yellow brown with small siphuncular pores and resemble the immatures of Trama species.

Alate Protrama radicis have never been found - only apterae and alatiform apterae are known.

Protrama radicis lives in ant attended colonies on the roots of various Asteraceae, especially thistles (Cirsium and Carduus) but also Arctium, Centaurea, and Cynara. They feed on the roots close to the soil surface. They reproduce parthenogenetically throughout the year, and no sexual morphs have been found.

 

Biology & Ecology

We first found Protrama radicis in August 2018 on the root of spear thistle (Cirsium vulgare) on Winchelsea Beach in East Sussex, very close to where we found Trama maritima  on Picris echioides in 2016. Many of the spear thistle there had been ant-tented with sand grains and plant fragments by colonies of the short-haired thistle aphid (Brachycaudus lateralis ). One tented spear thistle in 2018 instead had a large colony of Protrama radicis on the roots, just below the stem base. The picture below shows an adult (centre) surrounded by immatures.

This adult appears to be rather lightly marked compared to the adults shown above, but it is possible that this is because it has only recently moulted to the adult stage. Immature Protrama radicis are usually a little more orange-yellow than those of Trama maritima (see picture below).

Alternatively they may be light green (see picture below).

Paul (1977)  says that alatae are rare, but Blackman et al. (in press)  say that alatae have not yet been found of this species.

 

Other aphids on same host:

Acknowledgements

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

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

  • Blackman, R.L. et al. (in press). Aphids Anoeciinae, Lachninae, Eriosomatinae, Phloeomyzinae, Thelaxinae, Hormaphidinae, Mindarinae. Handbooks for the Identification of British Insects 2(8). Royal Entomological Society of London.

  • Paul, R.G. (1977). Aspects of the biology and taxonomy of British myrmecophilous root aphids. PhD thesis. Imperial College, London. Full text