Tubaphis ranunculina

Identification & Distribution

Adult apterae of Tubaphis ranunculina are deep yellow with pale appendages. The antennae are about as long as the body, with a terminal process 1.9-2.5 times the length of the base of the sixth antennal segment. The apical segment of the rostrum is 1.0-1.1 times the length of the second hind tarsal segment. The siphunculi are rough and thin, but broadening at the base and with a large flange. The cauda is blunt, tipped with white hairs, constricted at the base and with the apical half narrower than the basal half.

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

Tubaphis ranunculina does not host alternate but remains all year round on the underside of leaves of buttercups (Ranunculus species). Creeping buttercup (Ranunculus repens), meadow buttercup (Ranunculus acris) and Ranunculus velutinus are utilized in Europe, Ranunculus subcorymbosum in the Far East of Russia, and Ranunculus japonicus in Japan. Oviparae and alate males develop in autumn. They are not attended by ants. Tubaphis ranunculina has a wide distribution throughout Europe and much of Asia to Japan.

Biology & Ecology

Life cycle

Tubaphis ranunculina is not especially rare - it is in fact one of the commoner species in meadow communities (Borowiak-Sobkowiak et al., 2008). However, since it lives on the undersides of the leaves, and does not seem to develop very large colonies, one is unlikely to notice Tubaphis ranunculina unless one is specifically looking for it.

We first found this species in early June in the Long House Garden situated in the South Downs hamlet of West Dean in East Sussex. The garden is part formal and part 'wild garden' with lots of wild flowers, including both creeping and meadow buttercups. Searching the underside of the leaves quickly revealed a small population of Tubaphis ranunculina on the creeping buttercups. As is so often the case, having found this species on one site, we found it again the following day - in our own garden a few feet from the back door on a patch of creeping buttercups.

Being early June, aphid populations were likely to be near their peak, and not surprisingly some of the fourth instar nymphs had wing buds, indicating they were destined to become alates. Crowding is one of the main factors which induces the development of winged forms in aphids.

Tubaphis ranunculina sexual forms develop in the autumn - winged males and wingless oviparae - and after mating, the oviparae deposit eggs on the leaves of their host. The ovipara and the male are described by Stekolshchikov et al. (2014).

Colour

Although adult apterae of Tubaphis ranunculina are often described as yellow to yellow-green, all those we have found would be better described as deep yellow to orange-yellow (see picture below), not so very different from the yellow of buttercup flowers.

However they do not, it seems, get the yellow carotenoid pigment from buttercups as they feed exclusively on the leaves (albeit they may get the 'precursor' from the leaves).

Tubaphis ranunculina alates are a little paler (see picture below), and the immatures are indeed pale yellow-green.

Natural enemies

There was no evidence of any predation occurring in early June, but syrphid eggs were being deposited on the buttercup leaf undersides, suggesting that syrphid larvae might be important predators later in the season.

A parasite was present on one of the buttercup aphids in June - a parasitic larval trombidiid mite.

Larval trombidiid mites suck the haemolymph of aphids, reducing their reproductive output and killing them when there are several feeding on the same aphid. We have found them parasitizing many aphid species in Britain (see mites parasitizing aphids).

Other aphids on same host:

Blackman & Eastop list about 14 species of aphid which feed on Ranunculus acris worldwide (Show World list). Of those aphid species, Baker (2015) lists all 14 as occurring in Britain (Show British list).

Blackman & Eastop list about 10 species of aphid which feed on Ranunculus repens worldwide (Show World list). Of those aphid species, Baker (2015) lists all 10 as occurring in Britain (Show British list).

Acknowledgements We especially thank Robin & Rosie Lloyd, The Long House Garden, for their kind assistance and permission to sample. 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 Borowiak-Sobkowiak, B. et al. (2008). Aphids/Hemiptera, Aphidoidea/ on meadow communities from the Molinio-Arrhenatherertea class. Aphids and Other Hemipterous Insects 14, 51-61. Full text Stekolshchikov et al. (2014). Detailed description of oviparous females and males of Tubaphis ranunculina (Homoptera: Aphididae) with comments on the species distribution. Zoosystematica Rossica 23(2), 219-233. Full text