Macrosiphoniella asteris

Identification & Distribution

Adult apterae of Macrosiphoniella asteris are reddish brown suffused with green with a bronze sheen and sometimes a little wax powdering (see pictures below - although these may be oviparae). Dorsal hairs and their black scleroites are sparse and mainly arranged in longitudinal rows. The apical segment of the rostrum (RIV+V) is rather short, only 0.7-0.8 times the length of the second hind tarsal segment; it is not stiletto shaped as in other Macrosiphoniella, but has slightly convex margins. The antesiphuncular sclerites are rather large. The black siphunculi are 1.0-1.2 times the length of the cauda, which is dusky and paler than the siphunculi. The body length of adult Macrosiphoniella asteris apterae is 2.3-3.1 mm.

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

Macrosiphoniella asteris lives only on sea aster (Aster tripolium), feeding on the upper parts of the stems and the flowers. The species seems to be rare in Britain, but is found in coastal areas over most of Europe.

Biology & Ecology

Less is known about the ecology of the bronze sea aster aphid than is the case for some other salt marsh specialists. Healy (1975) investigated the salt marsh fauna of North Bull Island, near Dublin in the Republic of Ireland, during 1961-1963.

Sea aster (Tripolium pannonicum) (see picture above) was found to host two salt marsh specialists: Aphis tripolii and Macrosiphoniella asteris. Colonies of Macrosiphoniella asteris were found on the sea aster in the marsh from July to September.

Hopkins et al. (2002) noted that Macrosiphoniella asteris is very rare in Britain, with (at that time) the only record since Walker in 1847 being from Theobald (1926) who found it "occurring in very small numbers at Swale and Stour near Sandwich, Kent". We have looked for this species in various salt marsh sites in Hampshire, Sussex and Kent. We have so far found it in only one location - in Keyhaven salt marsh in Hampshire in two consecutive years. In 2018 we visited in October and there were sexuales present. The image below shows the small dark male of Macrosiphoniella asteris.

There were also a few immatures present (see picture below).

The following year we visited Keyhaven salt marsh in September, a month earlier, and found good numbers of bronze sea aster aphids on the sea aster.

Most of the adults had some offspring close to them. The nymph below on the aster petal appears to have 5 antennal segments, indicating it is a second instar nymph: For most aphid species, instar I has 4 antennal segments, instar II has 5 segments, and instars III, IV and adults have 6 antennal segments.

The picture below shows another adult Macrosiphoniella asteris resting besides the exuvium from its last moult.

Other aphids on same host:

Macrosiphoniella asteris has not been recorded on any Aster species, and has only been recorded on 1 Tripolium species (Tripolium pannonicum).

Blackman & Eastop list 6 species of aphid as feeding on sea aster (Tripolium pannonicum) worldwide, and provide formal identification keys for aphids on Aster species (Show World list). Of those aphid species, Baker (2015) lists all 6 as occurring in Britain (Show British list).

Acknowledgements 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 Healy, B. (1975). Fauna of the salt-marsh, North Bull Island, Dublin.. Proceedings of the Royal Irish Academy 75 B, 225-244. Full text Hopkins, G.W. et al. (2002). Identifying rarity in insects: the importance of host plant range. Biological Conservation 105, 293-307.  Full text Theobald, F.V. (1926). Plant Lice or Aphididae of Great Britain. Vol. 2. Headley Bros., London.