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Genus Nasonovia

Currant - daisy aphids

Species Overview: Genus Nasonovia  Nasonovia compositellae  Nasonovia pilosellae  Nasonovia ribisnigri 

Genus Nasonovia [Macrosiphini]

Medium-sized green or reddish, rather shiny aphids with a well-marked dorsal sclerotic pattern of pigmented paired intersegmental muscle plates. Adult viviparae may be winged or wingless. There are distinct antennal and median tubercles and the antennae are rather long. The siphunculi are cylindrical and rather long, with little or no apical reticulation The cauda is elongate and rather blunt finger-shaped.

There are about 30-45 species worldwide which host alternate between currants (Grossulariaceae) and various daisies (Asteraceae), among which the most important are lettuce (Lactuca), Crepis and various species of Hieracium. They are not attended by ants. One species is an important cosmopolitan pest of lettuce.

 

Nasonovia compositellae (Black-backed daisy aphid)

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.

Nasonovia compositellae lives all year round 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.

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Nasonovia pilosellae (Hawkweed aphid)

Medium-sized yellowish-green rather shiny aphids with a well-marked dorsal sclerotic pattern of pigmented paired intersegmental muscle plates. The siphunculi are cylindrical and rather long, with little or no apical reticulation The cauda is elongate and rather blunt finger-shaped. The first segment of the hind tarsus has two hairs. The ratio of the length of the terminal process of the last antennal segment to its base ranges from 5.7-8.0.

 

The hawkweed aphid lives all year round on a few related species of hawkweed, namely the orange hawkweed (Hieracium auranticum), common hawkweed (Hieracium lachrenalii) and the mouse-ear hawkweed (Hieracium pilosella).

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Nasonovia ribisnigri (Currant-lettuce aphid)

Nasonovia ribisnigri apterae on the primary host (gooseberry and blackcurrant, see first picture below) are shiny green with no dark markings. On their secondary host (various members of the daisy family) Nasonovia ribisnigri apterae are more variable in colour, ranging from green to yellow or pink, and have dark transverse bands on the outer parts of each abdominal segment (see second picture below). The ratio of the length of the terminal process of the last antennal segment to its base ranges from 7.0-11.4. The first segment of the hind tarsus has three hairs.

 

Nasonovia ribisnigri siphunculi are pale with dark tips. They are at least as long or longer than the cauda and taper slightly. The cauda is finger shaped, not constricted and the same colour as the basal part of the siphunculi. The body length of Nasonovia ribisnigri apterae is 1.3-2.7 mm.

Alate Nasonovia ribisnigri (see picture above) have a conspicuous pattern of black abdominal markings. They have 23-66 secondary rhinaria on the third antennal segment, 2-14 on the fourth segment and none on the fifth segment.

The currant-lettuce aphid host alternates from currants (Ribes spp.), especially gooseberry and blackcurrant, to various Asteraceae, including lettuce, as well as Brassicaceae, Scrophulariaceae and Solanaceae. Nasonovia ribisnigri is found throughout Britain and continental Europe east to Ukraine, and has been introduced to North and South America.

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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).

Useful weblinks 

References

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