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Thistle-root aphid, Daisy-root aphidOn 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.
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 (see picture below) are usually a little more orange-yellow than those of Trama maritima.
Alternatively they may be light green (see picture below).
Our second encounter with Protrama radicis came when one of our correspondents, Maria Fremlin, found some aphids feeding on the roots of some globe artichokes (Cyanara cardunculus).
Protrama radicis has been attended by ants - specifically the yellow meadow ant (Lasius flavus) - on each occasion we have found them. Those at Winchelsea beach spurned out attempts to photograph them, but those on the globe artichoke roots were much more obliging. The image below shows an ant imbibing honeydew from the anus of an aphid.
If they viewed our disturbance of the aphid colony as excessive, the ants picked up the aphids in their jaws and moved them to a safer, more secluded, feeding site.
Other aphids on same host: