Uroleucon hypochoeridis

Identification & Distribution:

Uroleucon hypochoeridis is a large pinkish-grey aphid with pale legs that are darkened towards the apices of the segments. The apical segment of the rostrum (RIV+V) is usually shorter than, or similar in length to, the second segment of the hind tarsus (HTII) (cf. Uroleucon cichorii which has RIV+V longer than HTII). Abdominal hairs are placed on scleroites and the crescent-shaped antesiphuncular sclerites are prominent. The coxae are dusky or dark, darker than the basal parts of femora. The cauda is pale, usually with about 17 hairs.

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

The large cat's ear aphid lives on the stems of cat's ear (Hypochoeris radicata), autumn hawkbit (Leontodon autumnalis) and related species. Oviparae and alate males occur from late August to October. It is found throughout Europe.

Biology

Life cycle

Eggs hatch in spring to give fundatrices. Uroleucon hypochoeridis are monoecious holocyclic, with sexuales in late August-October. Oviparae have dark swollen hind tibiae. Males are green, and are alate. The first image below shows an immature male (top-right), an immature ovipara (bottom-left), plus two (predatory) syrphid larvae and a syrphid egg. The second image is a mature male.

Natural enemies

Dirk Baert has reported parasitism of Uroleucon hypochoeridis by Praon yomenae. The pictures below show female Praon yomenae, the first reared from Uroleucon hypochoeridis in Belgium, the second is from the CBG Photography Group.

First image above copyright Dirk Baert, second image CBG Photography Group, both under creative common licence.

Diagnostic characteristics of Praon yomenae include antennae of female with 18-19 segments, wing veins 2RS and r+m absent, and m-cu partly missing. Labelling of braconid wing veins is provided here by Zikic et al. (2017). The main hosts of this parasitoid are in the Macrosiphini, especially Uroleucon species. Praon yomenae is thought to have a wide distribution throughout the Palaearctic zone, but precise distribution is unclear because of difficulties in separating members of the "dorsale-yomenae" group (see Mitrovski-Bogdanovic et al., 2014).

Other aphids on same host:

• Blackman & Eastop list 24 species of aphid as feeding on cats ear (Hypochoeris radicata) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 21 as occurring in Britain (Show British list).

• Blackman & Eastop list 17 species of aphid as feeding on autumn hawkbit (Leontodon autumnalis = Scorzoneroides autumnalis) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 15 as occurring in Britain (Show British list).

Acknowledgements Our particular thanks to Roger Blackman for images of his clarified slide mounts, and to Dirk Baert in Belgium for images of Aphidius colemani. 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 Mitrovski-Bogdanovic et al. (2014). The Praon dorsale-yomenae s.str. complex (Hymenoptera, Braconidae, Aphidiinae): Species discrimination using geometric morphometrics and molecular markers with description of a new species. Zoologischer Anzeiger 253(4), 270-282. Abstract Zikic et al (2017). Evolutionary relationships of wing venation and shape in Aphidiinae (Hymenoptera: Braconidae). Organisms, diversity and evolution 17, 607-617. Abstract