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Dysaphis apiifolia

Hawthorn-parsley aphid, Rusty banded aphid

Identification & Distribution  Biology & Ecology  Damage & Control 

Identification & Distribution:

The fundatrix of Dysaphis apiifolia is indistinguishable from that of several related species, namely Dysaphis crataegi,  Dysaphis angelicae  and Dysaphis lauberti. We refer to these species as the Dysaphis crataegi species group (the Hawthorn-umbellifer aphids). On the primary host the plump fundatrix (see picture below) of Dysaphis crataegi species group is bluish grey and densely powdered with wax. Their antennae are short at about 0.3 times the body length. The terminal process is 1.3-2.0 times the base of the last antennal segment. The siphunculi of aphids in this species group are quite short, about 0.08-0.09 times the body length and 1.4-1.8 times the cauda. The body length of the Dysaphis crataegi fundatrix is 1.7-2.3 mm.

The fundatrix induces a cherry-red to crimson curled-leaf gall on hawthorn (see second picture above). The galls caused by the Dysaphis crataegi species group are also indistinguishable from each other. Nearly all of the generation produced in the gall are winged (see pictures below). These winged adult females are known as 'spring migrants'.

These emigrant alates can be identified to species. Dysaphis apiifolia emigrant alates have the following characteristics:

  • Most individuals (all in summer and autumn) have paired or unpaired marginal tubercles on abdominal tergite VII (cf. Dysaphis crataegi where summer and autumn alatae never have paired marginal tubercles on abdominal tergite VII).
  • The hairs on abdominal tergite 8 are usually short and blunt, rarely more than 30 µm in spring migrants and not more than 26 µm in summer and autumn. (cf. Dysaphis crataegi on which the longest hairs on abdominal tergite 8 are 18-87 µm.

The Dysaphis apiifolia alates migrate to the ground level parts of various Apiaceae. Apterae on the secondary host (see pictures below) are yellowish grey or greenish grey and lightly wax powdered. The longest hairs on abdominal tergite 8 are at most 11-36 µm in length, and rarely greater than 30 µm. The pictures below show adult apterae and immatures on alexanders (Smyrnium olusatrum) in southern England.

The micrographs below show dorsal and ventral views of an adult aptera of Dysaphis apiifolia in alcohol.

The hawthorn-parsley aphid can be found on a wide range of Apiaceae, especially parsley (Petroselinum), but also hemlock (Conium, celery (Apium), fennel (Foeniculum and alexanders (Smyrnium). Dysaphis apiifolia has not been classified into various subspecies determined by the secondary host species. Host alternation is often present in Europe, but permanent parthenogenetic populations are also common in Europe and other parts of the world.

 

Biology & Ecology:

We have found colonies of Dysaphis apiifolia on alexanders (see pictures of live apterae above and below) in East & West Sussex.

We have also provisionally identified colonies on fennel at Rye Harbour, East Sussex, as being Dysaphis apiifolia (see two pictures below).

 

On the secondary host Dysaphis apiifolia is nearly always attended and, generally, sheltered by ants (see picture below).

It is rare to find predators when Dysaphis apiifolia are ant-attended, but they are sometimes parasitized, for example by Aphidius colemani and Lysiphlebus testaceipes (Stary et al., 2007 )

 

Damage and control

Dysaphis apiifolia can damage celery crops by stunting growth, by transmitting celery yellow spot virus and by contaminating the crop with honeydew and debris (University of California ).

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

  •  Stary, P. et al. (2007). Aphid parasitoids (Hymenoptera, Braconidae, Aphidiinae) and their associations related to biological control in Brazil. Revista Brasiliera de Entomologia 51(1), 75-83. Full text 

  •  University of California. Pest Management Guidelines: Celery Full text