Dysaphis apiifolia

Identification & Distribution:

The fundatrix of Dysaphis apiifolia induces a cherry-red to crimson curled-leaf gall on hawthorn (see first picture below). Neither the leaf gall nor the fundatrix of Dysaphis apiifolia can be distinguished from others of the Dysaphis crataegi species group (the hawthorn-umbellifer aphids: Dysaphis crataegi, Dysaphis angelicae, Dysaphis apiifolia and Dysaphis lauberti). On the primary host the plump fundatrix (see second picture below) of members of this 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. Nearly all of the generation produced in the gall are winged (see third picture below) and migrate to the ground level parts of various Apiaceae. These winged adult females are known as 'spring migrants' or emigrant alates

The alate can be identified to species. Most individuals of alate Dysaphis apiifolia (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 VIII 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 alates on which the longest hairs on abdominal tergite VIII are 18-87 µm). Apterae on the secondary host (see fourth picture above) 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. Those pictured above were feeding 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 clarified slide mounts below are of adult, viviparous female Dysaphis apiifolia : fundatrix, wingless from secondary host, and winged spring migrant.

Micrographs of clarified mounts by permission of Roger Blackman, copyright AWP all rights reserved.

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:

On secondary host

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 alexanders and fennel at Rye Harbour, East Sussex, as being Dysaphis apiifolia (see two pictures below).

Ant attendance

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)

Other aphids on same host:

Dysaphis apiifolia has been recorded from 2 Crataegus species (Crataegus azarolus, Crataegus monogyna).

Blackman & Eastop list 16 species of aphid as feeding on common hawthorn (Crataegus monogyna) worldwide, and provide formal identification keys.

Of those aphid species, Baker (2015) lists 15 as occurring in Britain: Aphis fabae, Aphis gossypii, Aphis pomi, Aphis spiraecola, Aulacorthum solani, Dysaphis angelicae, Dysaphis apiifolia, Dysaphis crataegi, Dysaphis lauberti, Dysaphis ranunculi, Ovatus crataegarius, Rhopalosiphum oxyacanthae, Ovatus insitus, Prociphilus pini and Rhopalosiphum rufulum.

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 Our particular thanks to Roger Blackman for images of his clarified slide mounts. 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