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Dysaphis gallica

Ivy-leaved toadflax aphid

Identification & Distribution  Biology & Ecology 

Identification & Distribution:

The aptera of Dysaphis gallica has been described variously as 'leaden coloured' and 'dark mottled blackish green, usually with a reddish tinge at bases of siphunculi'. The reddish tinge is more apparent in fourth instar nymphs (see below). The head has quite prominent antennal tubercles and a scabous median frontal tubercle The siphunculi are dark at least towards the apices and are 2.4 to 3.3 times the length of the short, helmet-shaped cauda. The body length is 1.2-1.6 mm.

 

The alate has 27-41 secondary rhinaria on the third antennal segment, 16-35 on the fourth antennal segment and 0-8 on the fifth antennal segment.

 

The aphid has mostly been found on the secondary hosts - various members of the Scrophulariaceae, namely Antirrhinum majus (common snapdragon), Cymbalara muralis (ivy-leaved toadflax) and Veronica (eyebright). The primary host appears to be apple (Malus following its discovery on that host in Pakistan. The species has been recorded on its secondary hosts in England, France, Switzerland, Italy, Sicily and Israel.

 

Biology & Ecology:

We have found Dysaphis gallica in small numbers on ivy-leaved toadflax (Cymbalaria muralis) growing on old walls in several coastal villages of East Sussex, UK. The aphids were active and reproducing from early March through to June.

Not a lot is known about this species. The primary host has been tentatively identified as apple (Malus) following its discovery on apple in pseudogalls by Naumann-Etienne & Remaudière (1995)  in Pakistan. Various transfer experiments have been attempted in Europe, but aphids reared on secondary hosts failed to feed on a range of likely primary hosts. Our observations of reproducing viviparae in March suggest it may not host alternate in UK, but remains all year on its secondary host Cymbalaria muralis (ivy-leaved toadflax).

 

The aphid is cryptically coloured resembling the leaves and flower buds of its food plant. The plant (see above) grows on old walls in south and southwest Europe, but is invasive in many parts of the world - including Britain and the USA.

 

We found no predators or parasitoids associated with the aphid populations, but one appeared to be infected with an orange Entomopthora fungus (see picture above).

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

  •  Naumann-Etienne, K. & Remaudière, G. (1995). A commented preliminary checklist of the aphids (Homoptera: Aphididae) of Pakistan and their host plants. Parasitica 51, 1-61. Abstract