InfluentialPoints.com
Biology, images, analysis, design...
Aphids Find them How to ID AphidBlog
"It has long been an axiom of mine that the little things are infinitely the most important" (Sherlock Holmes)

 

 

Identification & Distribution

Adult apterae of Trama caudata (see first picture below) are whitish, pale yellow or brownish with no sclerotic bands. Trama caudata is differentiated from the closely related Trama maritima  by having a relatively shorter antennal segment III relative to the lengths of antennal segments IV and V. So for Trama caudata antennal segment III is 1.80-2.35 (usually 2.0-2.2 times) the length of antennal segment IV, and 0.90-1.35 times the length of antennal segment V. (cf. Trama maritima for which antennal segment III is 2.1-2.8 times (usually 2.4-2.7 times) the length of antennal segment IV, and 1.35-1.80 times the length of antennal segment V). Siphuncular pores are present on very low cones. The body length of the adult aptera is 2.5-3.3 mm.

The alate viviparous female (not pictured) has dark dorsal and marginal sclerites on the abdomen. Immature Trama caudata (see second picture above) are usually straw-coloured.

Trama caudata feeds on the roots of plants in the daisy family (Asteraceae). They are commonly found on agricultural crops such as chicory (Cichorium) and lettuce (Lactuca), as well as non-cultivated genera including cats ears (Hypochaeris), oxtongues (Picris), hawkbits (Leontodon), sowthistles (Sonchus) and dandelions (Taraxacum). Sexual morphs have not been found, so it is assumed that all reproduction is parthenogenetic and that they overwinter as viviparae. Trama caudata occurs over most of Europe, but has yet to be found in Scandinavia.

 

Biology & Ecology

Life cycle

We have so far only found Trama caudata on cultivated land, specifically on an allotment in Colchester, Essex. Colonies of the garden root aphid were feeding on the roots two members of the Asteraceae, namely chicory (Cichorium intybus) and lettuce (Lactuca).

The adults and older nymphs can often be found feeding on the main tap root (see picture below).

But the younger nymphs often feed on the rootlets - as shown in the picture below.

 

The Trama caudata shown above were all found in March, well before the 'traditional' aphid season, supporting the supposition that populations reproduce parthenogenetically through the year with no sexual reproduction. We will nevertheless continue to watch out for sexuales in autumn following the discovery of sexuales of Trama troglodytes by Blackman et al. (2001). 

 

Ant attendance

Trama caudata is an obligate myrmecophile (Paul, 1977 ), meaning the aphids are always attended by ants.

The ants spend much of their time caressing and tapping the aphids with their antennae in order to encourage honeydew production, as well as guarding them against predators.

As soon as a drop of honeydew is produced, an ant moves to the rear of the aphid and drinks it.

Ants that obtain honeydew from ants are likely to share the food with other nest members by regurgitation, a process known as trophallaxis (see for example ants attending Aphis loti ).

 

Other species on the same host

Acknowledgements

We are extremely grateful to Maria Fremlin  for her most generous assistance, and permission to sample her allotment in Colchester, Essex.

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. (2001). Occurrence of sexual morphs in Trama troglodytes von Heyden, 1837 (Hemiptera, Aphididae). Journal of Natural History 35 (1), 779-785. Full text 

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