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Dysaphis aucupariae

Wild service aphid

On this page: Identification & Distribution  Biology & Ecology 

Identification & Distribution:

The spring generations of Dysaphis aucupariae live in characteristic reddish to yellowish rolled or twisted pseudogalls on the leaves of Sorbus torminalis (wild service tree) (see first picture below). Apterae of Dysaphis aucupariae on their primary host are heavily wax-powdered (see second picture below). The colour under the wax is greyish green or pinkish yellow with distinctive brownish to reddish areas at siphuncular bases.

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These reddish areas are often visible on recently ecdysed aphids (see picture below). The head, antennae (except segment III), legs, siphunculi and cauda are all dark. Their antennae are about 0.6 to 0.7 times the body length. The dorsum of Dysaphis aucupariae is membranous with cross bars on the thorax and abdominal tergites VI and VIII only, and smaller sclerites on other segments. The siphunculi are 2.5 to 3.1 times the length of the triangular cauda. Their body length is 2.2-2.6 mm.

The alate viviparous female Dysaphis aucupariae from the primary host has the abdomen ochreous to greenish-yellow with a black trapeziform dorsal patch on tergites III-V and spinal cross bands on tergites I and II. apterae on the secondary host are pinkish ochreous with reddish or brownish areas at the siphuncular bases.The alate from the secondary host is reddish ochreous with a blackish sclerotic pattern.

Dysaphis aucupariae host alternates from wild service tree to various plantain species (Plantago lanceolata, Plantago media, Plantago major), where they live in the grooves between the veins on the undersides of the leaves. They are often attended by ants. Dysaphis aucupariae is found in Europe east to Crimea and the Caucasus and the Azores. It has (presumably) been introduced to Australia, New Zealand, Argentina and Washington, USA.

 

Biology & Ecology:

In April the fundatrices of Dysaphis aucupariae stimulate the development of rolled pseudogalls (see picture below).

The pseudogall of Dysaphis aucupariae is initially pale yellow green, but soon becomes tinged with red. Its form is somewhat variable, either curled from the the leaf apex to the base (see above), or laterally (from the sides of the leaf inwards) (see below).

Guest image copyright Dr Jula Werres, INRES,  all rights reserved

Early in the year many more leaves may have limited galling than actually develop to an 'occupied' pseudogall. We initially assumed that this was the result of some of the gall initiators being predated before they could found a colony. However, very few predators were found apart from a few earwigs. Another possibility was that some of the rather mobile young larvae (see picture below) were visiting and feeding on several leaves before settling on one as the eventual site to found a colony.

This would have the advantage of stimulating a number of empty pseudogalls which would confuse potential bird predators.

The affected leaves eventually turn golden yellow (see second picture below).

Guest image copyright Dr Jula Werres, INRES,  all rights reserved

Later in the year colonies can sometimes develop on more mature leaves (see picture below) which then develop very little apparent galling.

Aphid colonies in the pseudogalls are heavily waxed (see picture below) and often attended by ants.

Despite this, predators are usually present, especially syrphid larvae (see second picture below).

Guest image copyright Dr Jula Werres, INRES,  all rights reserved

Parasitoids also enter the galls. The picture below shows a mummified aphid from a leaf gall in Kent.

Sometimes all the leaves on a tree are infested with aphids and then, some weeks later, the whole tree is bare branched. Sunde (1984)  records the apparent establishment of a Dysaphis aucupariae population in New Zealand. Since the wild service tree is not present in New Zealand, it is generally assumed that the population is maintaining itself on the secondary host. Buckton (1877) reports that the species also feeds on rowan (Sorbus aucupariae) which is found in New Zealand. Possibly it does use rowan in New Zealand, but in Europe it is found far more often on wild service tree.

Acknowledgements

Our sincere thanks to Jula Werres for some of the pictures shown above. We also thank the UK Forestry Commission Bedgebury Pinetum  for their kind assistance, and permission to sample.

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

  •  Sunde, R.G. (1984). New records of plant pests in New Zealand 4. 7 aphid species (Homoptera: Aphidoidea). New Zealand Journal of Agricultural Research 27, 575-579.