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Garden root aphidOn this page: Identification & Distribution Biology & Ecology Other aphids on the same host
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.
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
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).
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