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Short-tailed plantain aphidOn this page: Identification & Distribution Biology & Ecology Other aphids on the same host
Identification & Distribution:
Adult apterae of Brachycaudus lucifugus are yellowish-green with dark cross bars on the pronotum and mesonotum, a transverse row of sclerites on the metanotum, and a shiny dark brown to black dorsal patch on abdominal segments 1-5. The patch frequently has pale windows or is broken into cross-bands. Abdominal tergite 8 bears 4 very short (less than 10 μm) hairs in a single row, like the dorsal hairs on more anterior segments. The black siphunculi are about double the length of the cauda. The cauda is rounded, as long as it is wide, with 6-9 hairs. The body length of adult apterae is 1.4-2.0 mm.
The alate of Brachycaudus lucifugus does not have broad cross bands or a large dark patch on the dorsal abdomen, but has transverse bars on tergites 7 and 8 with rarely a few sclerotic spots forming lines on tergites 4-6 only.
The short-tailed plantain aphid lives on roots, and root collar, and at the leaf bases of ribwort plantain (Plantago lanceolata). There is no host alternation. Brachycaudus lucifugus is usually ant attended, as in the second picture above. Oviparae and small apterous males can be found in autumn. In England it is restricted to southern counties. Elsewhere in Europe Brachycaudus lucifugus is known from Germany, Hungary, Italy, Poland and Switzerland.
Biology & Ecology:
We have only found Brachycaudus lucifugus in one coastal location - at Birling Gap in East Sussex - where its host plant, ribwort plantain (Plantago lanceolata) (see pictures below) grows in abundance.
The stem base of the plant is tented with earth by ants, specifically Lasius flavus, thus indicating the likelihood of an aphid colony on the plant. In this case, as soon as the colony was revealed, Brachycaudus lucifugus lived up to its Latin name 'lucifugus', meaning 'fleeing from light', and rapidly fled the scene. This made it very difficult to photograph especially in the case of adults - hence our less than impressive photos!
The yellow meadow ants assisted in the rapid departure of the aphids by picking them up in their jaws (see picture above) and carrying them away - presumably to safer locations.
Stroyan (1964) notes the close morphological similarity between Brachycaudus lucifugus and Brachycaudus linariae, a species found only on yellow toadflax (Linaria), and suggests they exemplify the close affinity existing between certain phytophagous insects associated with species of Plantaginaceae and Scrophulariaceae. A similar species pair is also found in the genus Dysaphis with Dysaphis plantaginea on Plantago lanceolata and Dysaphis gallica on Cymbalara muralis (ivy-leaved toadflax).
Stroyan (1964) also noted a close parallel between the aphid Brachycaudus lucifugus and the Glanville fritillary butterfly (Melitaea cinxia), given that both feed on ribwort plantain and both (at least in Britain) have an extreme southern distribution being (at that time) only known to occur on the Isle of Wight and the Channel Islands. He postulated that Brachycaudus lucifugus would also be found to occur in parts of south-east Kent, and we have now found it in East Sussex.
Other aphids on the same host
Blackman & Eastop list 16 species of aphid as feeding on ribwort plantain (Plantago lanceolata) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 15 as occurring in Britain (Show British list).
The only species we have found feeding on Plantago lanceolata is Aphis plantaginis, another plantain root specialist (see picture below), which occurred together with Brachycaudus lucifugus in the same habitat. Aphis plantaginis is not, however, restricted to Plantago lanceolata, being equally common on other species such as hoary plantain (Plantago media). Also the populations of Aphis plantaginis that we have found were tended by a different ant species - Lasius niger rather than Lasius flavus.