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Identification & Distribution

Adult apterae of Staegeriella necopinata are yellowish-green or greyish-green aphids (see two pictures below), powdered ventrally with grey wax. The grey siphunculi are short and truncate, have a small but distinct apical flange, and are distinctly constricted below that flange. The siphunculi are 0.5-0.8 times as long as the grey finger-shaped cauda. The body length of adult Staegeriella necopinata apterae is 1.3-2.2 mm.

Immature Staegeriella necopinata are greenish with more or less extensive wax powdering especially intersegmentally. The alate has similar short truncate siphunculi, rather pale marginal sclerite and no abdominal patch.

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

Staegeriella necopinata does not host alternate, but remains all year round on bedstraws, mainly yellow bedstraw (Galium verum). It feeds on the stem, growing shoot and flower. Oviparae and alate males occur in autumn, with overwintering in the egg stage. Staegeriella necopinata is found in throughout Europe, although it is rare in Britain.

 

Biology & Ecology

Life cycle

Staegeriella necopinata - the bedstraw shoot aphid - is one of several aphid species largely restricted to bedstraws. It appears to be rather rare in the British Isles with few recent records of its occurrence. Wood-Baker & Hopkins (2000)  found the species in County Kerry, Ireland in 1997, and described the oviparae for the first time. Baker (2009)  observed this species feeding in large numbers on the flowering heads of several Galium verum plants growing in unimproved grassland at Porthkerry Park, Barry, in Wales. We found it for the first time in 2018, in Malling Down Nature Reserve in East Sussex.

The main host of Staegeriella necopinata is lady's bedstraw (Galium verum, see picture above). Other aphid species specific to bedstraws include Aphis galiiscabri and Linosiphon galiophagum (both mainly on hedge bedstraw, Galium mollugo), Hydaphias mosana (found at the stem base of lady's bedstraw) and Hydaphias hofmanni (found on the roots of either bedstraw species).

Staegeriella necopinata is found up the stem and on the flowers of lady's bedstraw, but it especially favours the growing point (see picture above).

The immatures (see first picture above) are distinctive, with blue-grey wax intersegmentally. The adult (see second picture above) has no wax on the dorsum.

As the plant grows the colony extends from the growing point down the stem (see picture above).

Sexual forms develop in autumn - the picture above shows the alate male Staegeriella.

Ant attendance

Staegeriella necopinata is not generally considered to be ant-attended, and none of the colonies we have found has been attended. However, Ozdemir et al. (2008)  has recorded ant attendance of Staegeriella necopinata on Galium verum by the ants Plagiolepis pallescens and Plagiolepis vindobonensis in Ankara Province, Turkey.

Associations

Staegeriella necopinata can be found in close association with Myzus cerasi,  a host alternating aphid species which uses Galium as its secondary host. The picture below shows an immature Myzus cerasi feeding beside an immature future alate male Staegeriella necopinata on the growing shoot of lady's bedstraw.

When this photo was taken (late September) the Myzus cerasi were producing alates (see fourth instar alatiform nymph below) which would migrate back to their primary host, cherry (Prunus cerasus).

Natural enemies

We found no predators or parasitoids attacking the colonies we found on lady's bedstraw in East Sussex. Baker & Broad (2013)  reported finding brown mummies of Staegeriella necopinata in Porthkerry Park, Barry in Wales. The parasitoid, Binodoxys brevicornis, proved to be a new species to Britain.

 

Other aphids on same host:

Staegeriella necopinata has been recorded on 9 Galium species: Galium aparine, Galium boreale, Galium ceratopodum, Galium glaucum, Galium intermedium, Galium lucidum, Galium mollugo, Galium rubrum and Galium verum.

Blackman & Eastop list 18 species of aphid  as feeding on lady's bedstraw (Galium verum) worldwide, and provide formal identification keys.

Of those aphid species, Baker (2015)  lists 14 as occurring in Britain: Aphis fabae,  Aphis galiiscabri, Aphis gossypii,  Aphis solanella,  Aulacorthum solani,  Dysaphis pyri,  Hydaphias hofmanni, Hydaphias mosana, Linosiphon galiophagum, Myzus cerasi,  Myzus langei, Myzus ornatus,  Myzus persicae  and Staegeriella necopinata.

Acknowledgements

We have made provisional 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

  •  Baker, E. (2009). Observations of aphids (Aphidoidea) new to Wales. British Journal of Entomology & Natural History 22, 235-246. Google Scholar 

  •  Baker, E. & Broad, G. R. (2013). Eight aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) new to Britain. British Journal of Entomology & Natural History 26, 187-197. Full text 

  •  Ozdemir et al. (2008). Investigations of the association between aphids and ants on wild plants in Ankara Province (Turkey). Mun. Ent. Zool. 3(2), 606-613. Full text 

  •  Wood-Baker, C.S. & Hopkins, G.W. (2000). The oviparous female of Staegeriella necopinata (Borner, 1939) (Hem., Aphididae). Entomologist's Monthly Magazine 136 (1628-1631), 53-54. Google Scholar