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Mallow aphidOn this page: Identification & Distribution Biology & Ecology Other aphids on the same host
Identification & Distribution:
Adult apterae of Brachycaudus malvae are pale green with separate black cross bars on thoracic segments, and an extensive shining black sclerotic shield on the dorsum (cf. Brachycaudus helichrysi which has no dark sclerotization on the dorsum). The hairs on the third antennal segment are very short, only 0.2-0.25 times the basal diameter of that segment. The last two fused apical rostral segments (RIV + V) are 0.165-0.190 mm in length. Marginal tubercles are often absent; if present they are usually only on the prothorax and abdominal tergites 2-4. Abdominal tergite 8 bears 10-14 short hairs, not in a single row. The siphunculi are black and cylindrical. The body length of Brachycaudus malvae apterae is 1.8-2.3 mm.
Brachycaudus malvae alates have a large black dorsal patch, which may be broken up to a greater or lesser degree into transverse bars. Their antennae each bear 21-30 secondary rhinaria on segment III and 0-3 on segment IV.
Brachycaudus malvae lives all year feeding on mallow (Malva) species with no host alternation. Aphid colonies are usually attended by ants. Sexual morphs do not appear to have been described. Brachycaudus malvae is found in Britain, Spain, Italy, southern Russia, Ukraine and China (an odd distribution suggesting the species has been overlooked in many countries).
Biology & Ecology:
In Britain Baker (2009) found large colonies of Brachycaudus malvae feeding on several common mallow (Malva sylvestris) plants, growing on the edge of a pebble beach at The Knap, Barry, in Wales during summer 2008. Feeding was concentrated on basal parts of the plants where they were sheltered by Lasius niger, but some aphids moved to feed on aerial parts as summer progressed.
We have found Brachycaudus malvae on several occasions in southern England, both in East Sussex and in Bedfordshire, sometimes sheltered by ants but sometimes not. The picture below shows a dense colony on mallow in East Sussex, with a single alate, several adult aptera and numerous immatures.
Brachypterous adults are not uncommon in several of the Brachycaudus species, and Brachycaudus malvae is no exception to this.
The pictures below show micrographs of a normal apterous adult of Brachycaudus malvae and of an apparently albino example of the same species.
There is a real dearth of information about Brachycaudus malvae in the literature. Coeur d'acier et al. (2008) using molecular techniques notes that Brachycaudus malvae is most closely related to Brachycaudus jacobi, a species which utilizes a quite different host family (Boraginaceae). Jousselin et al. (2010) uses Brachycaudus malvae as an example of how speciation in the genus has been via the acquisition of new somewhat distantly related hosts (in this case Malva) during the summer phase of the heteroecious (host alternating) life cycle.
Other aphids on same host:
Blackman & Eastop list 20 species of aphid as feeding on Mallow (Malva species) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 17 as occurring in Britain (Show British list).