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Strawberry tree aphidIdentification & Distribution Biology & Ecology Damage & Control
Identification & Distribution:Wahlgreniella nervata apterae are spindle-shaped and yellowish or green (see below first picture), sometimes mottled with reddish anteriorly (see below second picture). The femora do not have distinctly dark apices. Their siphunculi are slightly swollen rather symmetrically about their inner and outer faces, they have dark tips and a small flange. Winged viviparae of Wahlgreniella nervata have a green abdomen with variably developed dark dorsal cross-bands, sometimes coalescing into an irregular patch.
There are two subspecies:
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 ).
Biology & Ecology:
We have only found Wahlgreniella nervata arbuti in UK once, but this may have more to do with the scarcity of strawberry trees than of the aphid. The nymphs shown below came from the same well established colony as the two apterae shown above.
Predators had found the colony and there were several syrphid larvae present (see picture below).
Parasitoids had also been active (see picture of mummy below), but we were unable to determine the identity of the primary parasitoid, as only hyperparasitoids emerged.
Damage and control
The strawberry tree is grown as an ornamental tree, and the fruits may be used to make preserves.
The strawberry tree aphid is one of the very few pests of the tree, but there is little evidence it causes serious damage.