Macrosiphoniella sejuncta

Identification & Distribution:

Adult Macrosiphoniella sejuncta apterae are usually green mottled with brownish red, with no wax powdering (see first picture below). The antennae are rather dark, but with a very short pale section at the base of segment III. The first tarsal segment has only 3 hairs. Macrosiphoniella sejuncta siphunculi are greenish brown to brown with paler bases and the cauda is a pale greenish brown. The siphunculi are very thin, slightly swollen at the base, slightly widened at the apex, have reticulation on the apical 48-69%, and are 1.7 to 2.2 times the length of the cauda (cf. Macrosiphoniella millefoliiwhich has siphunculi 0.8-0.9 times as long as the cauda). The body length of the adult aptera is 2.5-3.1 mm.

The Macrosiphoniella sejuncta alate is much like the apterous viviparous female, but is more slender and has well developed marginal sclerites as well as presiphuncular sclerites (see second picture above). The third antennal segment has 30-40 rhinaria. The ovipara is similar to the apterous vivipara, but its cauda is slightly thicker and blunt, and the basal half of the hind tibia is swollen. The male is wingless and small with a body length of only about 2 mm.

The micrograph below shows an aptera viewed dorsally in alcohol.

The clarified slide mounts below are of adult viviparous female Macrosiphoniella sejuncta : wingless, and winged.

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

Macrosiphoniella sejuncta feeds on the older leaves close to the ground of yarrow (Achillea millefolium). The best way to find these aphids is to shake the host-plants over a sheet placed on the soil under the leaves. The species does not host alternate, but remains all year on yarrow - overwintering in the egg stage. Sexual forms can be found in September and October. The large mottled yarrow aphid is found across Europe east to Western Siberia.

Other aphids on same host:

Macrosiphoniella sejuncta has been recorded from 2 Achillea species (Achillea millefolium, Achillea ptarmica).

Blackman & Eastop list 46 species of aphid as feeding on yarrow (Achillea millefolium) worldwide, and provide formal identification keys.

Of those aphid species, Baker (2015) lists 26 as occurring in Britain: Aphis craccivora, Aphis fabae, Aphis gossypii, Aphis vandergooti, Aulacorthum solani, Brachycaudus cardui, Brachycaudus helichrysi, Coloradoa achilleae, Macrosiphoniella abrotani, Macrosiphoniella millefolii, Macrosiphoniella ptarmicae, Macrosiphoniella sejuncta, Macrosiphoniella tanacetaria, Macrosiphoniella tapuskae, Macrosiphoniella usquertensis, Macrosiphum euphorbiae, Metopeurum fuscoviride, Microsiphum millefolii, Myzus ascalonicus, Myzus cymbalariae, Myzus ornatus, Myzus persicae, Neomyzus circumflexus, Pleotrichophorus duponti, Trama troglodytes and Uroleucon achilleae.

Acknowledgements Our particular thanks to Roger Blackman for images of his clarified slide mounts. We also thank Middle Farm, East Sussex for their kind assistance, and permission to sample. 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).

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