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Nasonovia compositellae

Black-backed daisy aphid

Identification & Distribution  Biology & Ecology 

Identification & Distribution:

The adult aptera of Nasonovia compositellae has a black head, and black cross bars across the pronotum and mesonotum. There is an extensive shining black dorsal abdominal shield covering the metanotum and abdominal tergites 1-VI , and tergites VII and VIII with black cross bars. The body is dark green, often (as here) strongly tinged with orange-red. The antennae are 0.8-0.9 times the body length. The siphunculi are thick at the base and 1.3-1.6 times the length of the cauda. The cauda is finger-shaped with 7 hairs. The body length of the aptera is 1.8-2.5 mm.

 

There are two subspecies of Nasonovia compositellae:

  • Nasonovia compositellae subspecies compositellae has the antennal terminal process of the aptera from 3.3 to 6.7 (usually less than 5.7) times longer than the base of antennal segment VI (our pictures are all of this subspecies).
  • Nasonovia compositellae subspecies nigra has the antennal terminal process of the aptera from 5.3 to 7.8 (usually more than 5.7) times longer than the base of antennal segment VI.

The first image (below) is a micrograph of the adult aptera in alcohol. The second picture shows the lengths of the terminal process (PT) and base of antennal segment VI for a specimen of Nasonovia compositellae ssp. compositellae from the north of Scotland. In this case the PT/base ratio was 5.5, suggesting ssp. compositellae, as would be expected given it was captured in the far north of Scotland (see below).

 

Nasonovia compositellae feeds on hawkweeds (Hieracium species). In spring it feeds on the upper sides of the leaves which fold upwards to enclose the colonies, and later colonizing stems and flowers. Nasonovia compositellae subspecies compositellae produces sexuales in autumn and overwinters as eggs. It is found in the north and west of England and in Wales, Scotland and Ireland. Outside Britain it is only known from Norway and Iceland, so it is a true northern subspecies. Nasonovia compositellae ssp. nigra mainly overwinters as parthenogenetic viviparae. It is found in southern England and Wales, and is widely distributed in Europe.

 

Biology & Ecology:

We have only found this species in Britain on one occasion - Nasonovia compositellae subspecies compositellae at Dundreggan in Inverness-shire. There we found several colonies on Hieracium pilosellae. Blackman (2010)  comments that most British records so far come from another Hieracium species, Hieracium exotericum.

The colonies we found were quite heavily parasitized. The picture below shows several immature aphids which subsequently turned out to be parasitized.

The parasitoid which emerged was identified by Ed Baker as Aphidius hieraciorum.

Croft (2007)  identified the parasitoid Aphidius hieraciorum (together with the use of resistant varieties) as components for the integrated control of the currant-lettuce aphid (Nasonovia ribisnigri) under the low temperatures and short day lengths of a winter crop.

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

  •  Croft, et al. (2007). The identification of winter aphids in protected lettuce. Report to Horticultural Development Council, East Malling, Kent.. 14 pp. Abstract