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Aphidinae : Aphidini : Aphis cercocarpi
 

 

Aphis cercocarpi

Oceanspray -- cornlily aphid

On this page: Identification & Distribution Other aphids on the same host

Identification & Distribution

Adult apterae of Aphis cercocarpi (see first picture below) are shining lead-grey to greenish-black. Their antennae and legs are pale with the tips of the joints dusky and the tarsi, siphunculi, cauda, anal plate and genital plate black. The antennal terminal process is 1.3-2.2 times as long as of the base of antennal segment VI. The rostrum almost reaches the 3rd pair of coxae, and the apical rostral segment (RIV+V) is 1.2-1.7 times the length of the second hind tarsal segment (HTII). The abdominal dorsum is reticulated and has dark spots or patches, but no solid dark shield (cf. Aphis craccivora, which has an extensive solid dark shield on the abdominal dorsum). Abdominal tergites II-IV are usually without marginal tubercles, rarely with just 1 or 2 (cf. an undescribed Aphis sp. on Veratrum in western USA, which consistently has marginal tubercles on tergites II-IV). The tibial hairs are rather long, equalling the diameter of the tibia. The siphunculi are cylindrical, broadening at the base, and longer than the cauda (cf. Aphis schuhi, which has siphunculi shorter than the cauda). The short rather wart-like cauda is bluntly tapering to spatulate with a distinct constriction near the base, and bearing 4-12 hairs (cf. Aphis fabae, which has a cauda bearing 11-25 hairs). The body length of adult Aphis cercocarpi apterae is 1.0-2.3 mm.

Note: Aphis cercocarpi was originally thought to have been collected on Cercocarpus montanus (as Cercocarpus parvifolius), hence the specific name of Aphis cercocarpi (Gillette and Palmer, 1929). However, this is now thought to have been a host misidentification, with the true (primary) host being Holodiscus. Hence Jensen (2021) synonomized Aphis holodisci with Aphis cercocarpi. The aphid is now known to host alternate to Veratrum in summer, leading Jensen to also synonomize the Veratrum-feeding Aphis coweni with Aphis cercocarpi.

Images above copyright Andrew Jensen under a cc by-nc-sa licence.

Aphis cercocarpi alates (see second picture above) have a black head and thorax, and a blackish green abdomen. Their antennae are mostly dark, the tibiae are pale with blackish tips, and the siphunculi and cauda are dusky. There are 15-34 large round secondary rhinaria scattered over the entire length of antennal segment III, 0-13 secondary rhinaria on segment IV, and 0-1 rhinaria on segment V (rhinaria are absent in the aptera).

Aphis cercocarpi was until recently considered to be a monoecious holocyclic species on mountain mahogany (Cercocarpus spp.). Jensen (2021) has now shown experimentally that the species is instead heteroecious holocyclic, migrating from the primary host, ocean spray (Holodiscus spp.) to the secondary host, corn lily (Veratrum spp.). Blackman noted that the presence of apterous males in some locations indicates there is either life-cycle variation or that two cryptic species are involved. Jensen states this is a common species in Oregon and Washington, feeding on Holodiscus discolor. Aphis cercocarpi is often tended by ants. The species is known to occur in western USA and Canada.

 

Other aphids on the same host

Primary hosts

Aphis cercocarpi has been recorded from 2 ocean spray species (Holodiscus discolor, Holodiscus dumosus).

Secondary hosts
  • Aphis cercocarpi has been recorded from 4 corn lily species (Veratrum californicum, Veratrum dahuricum, Veratrum oxysespalum, Veratrum viride).

    Blackman & Eastop list 2 species of aphid as feeding on corn lily (Veratrum californicum) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 1 as occurring in Britain (Show British list).

Acknowledgements

Identification was made by Andrew Jensen by microscopic examination of preserved specimens. We have used the keys and species accounts of Gillette and Palmer (1929), Gillette and Palmer (1932) and Jensen (2021), together with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors and those listed in the reference sections 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

  • Gillette and Palmer (1929). New Colorado Aphididae. Annals of the Entomological Society of America 22, 1-32.

  • Gillette and Palmer (1932). The Aphidae of Colorado Annals of the Entomological Society of America 25, 369-496. Full text

  • Jensen, A.S. (2021). The aphids (Hemiptera: Aphididae) of Holodiscus (Rosaceae) in the USA. Proceedings of the Entomological Society of Washington 123(1), 75-119. Abstract