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Genus Wahlgreniella

Heather aphids

On this page: Genus Wahlgreniella  Wahlgreniella nervata 

Genus Wahlgreniella [Macrosiphini]

Wahlgreniella are rather large aphids which are similar to Amphorophora in many respects, but have fewer caudal hairs. Adult viviparae may be winged or wingless. The antennal tubercles are well developed with diverging or parallel inner sides. The antennae are rather long and thin. The siphunculi are long and swollen with no reticulation and a distinct flange. The cauda is tongue shaped.

Wahlgreniella is a small genus, with only 6 species in the world. Most live on plants of the heather family (Ericaceae), but with one on rose (Rosaceae) in North America. They do not host alternate, except perhaps Wahlgreniella nervata which may alternate from Arbutus to Rosa. Wahlgreniella are not ant attended.

 

Wahlgreniella nervata (Strawberry tree aphid)

Wahlgreniella nervata apterae are spindle-shaped and yellowish or green (see below first picture ssp. arbuti & second picture ssp. nervata), sometimes mottled with reddish anteriorly (see below third picture). The antennal tubercles have their inner faces divergent and smooth. The femora do not have distinctly dark apices. Their siphunculi are slightly swollen rather symmetrically about their inner and outer faces, and have dark tips and a small flange.

Winged viviparae of Wahlgreniella nervata (not pictured) have a green abdomen with variably developed dark dorsal cross-bands, sometimes coalescing into an irregular patch.

There are two subspecies (or divergent clones of the same species):

  1. Wahlgreniella nervata arbuti
    The apical segment of the rostrum (RIV+V) is longer than 1.3 times the length of segment two of the hind tarsus (HTII). The apterae in spring and summer are shining yellowish green. Aptera body length is 2.1-2.9 mm. On Arbutus (strawberry tree) and Arctostaphylos (manzanitas and bearberries), but in culture able to live on rose.
  2. Wahlgreniella nervata nervata
    RIV+V is shorter than 1.3 times the length of HTII. The apterae in spring and summer are pale green to dull mid-green. Aptera body length is 1.4-2.5 mm. This subspecies lives on rose (Rosa) but, in culture, able to live on strawberry tree.

In North America Wahlgreniella nervata apparently host alternates between rose (Rosa) and ericaceous plants (mainly strawberry tree, Arbutus), although the host alternation has not yet been experimentally verified. Parthenogenetic populations on both Rosa and Arbutus have been introduced into Europe, and are treated as separate subspecies. Wahlgreniella nervata is considered an invasive species, having been reported from Damask rose in Turkey (Barjadze, 2011 ), and as a new pest of rose in India (Joshi et al., 2014 ).

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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).

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References

  • Blackman, R.L. & Eastop, V.F. (2006). Aphids on the world's herbaceous plants and shrubs. Vols 1 and 2. John Wiley & Sons.

  • Heie, O.E. (1980-1995). The Aphidoidea, Hemiptera, of Fennoscandia and Denmark. (Fauna Entomologica Scandinavica) E.J. Brill, London