Pleotrichophorus gnaphalodes (Frosted sagebrush aphid) identification, images, ecology, control

Adult apterae of Pleotrichophorus gnaphalodes (see pictures below) are pale yellowish green, with a frosted appearance produced by dense capitate hairs. The antennae are mainly pale, but dusky from the apex of segment V. The tips of the rostrum and tibiae, and the entire tarsi are dark. The head has rather well-developed antennal tubercles, and a prominent median frontal tubercle. Antennal segment III bears 1-4 secondary rhinaria. Hairs on the antennae are very short, less than 0.5 times the basal diameter of segment III. The apical rostral segment (RIV+V) bears 1 basal, 2 dorsal and 3 lateral pairs of hairs, and has the distal part of RV is extended as a needle-like, cylindrical tip (cf. Pleotrichophorus parilis on Artemisia, which has RIV+V tapering from base to apex). The dorsal body integument is smooth to faintly striate, with a moderately dense cover of capitate hairs without distinct stems. The fore-, mid-, and hind-legs have 3, 3, 3 hairs on the first tarsal joints. Siphunculi are pale, sometimes with dusky apices (cf. Pleotrichophorus quadritrichus on Artemisia, which has dark siphunculi, and Pleotrichophorus quadritrichus ssp. pallidus, which has dusky siphunculi); they are cylindrical in shape and 0.8-1.6 times the caudal length. The cauda is stoutly elongate, constricted on the basal quarter and the apex broadly rounded, with 2 pairs lateral and 1 posterodorsal hairs. The body length of adult Pleotrichophorus gnaphalodes apterae is 1.4-2.2 mm.

Pleotrichophorus gnaphalodes (frosted sagebrush aphid) aptera on Artemisia (sagebrush) in Riverside County, California, USA on 24 Jan 2018; Jesse Rorabaugh

Images above copyright Jesse Rorabaugh under a public domain (CCO) licence.

The alate Pleotrichophorus gnaphalodes (not pictured) has the head and thorax brown and sclerotic, with dark brown antennae. The abdomen is pale, membranous, with dusky or light brown sclerites. The siphunculi, anal plate, cauda and anterior wing margins are dusky. Morphologically the alate is much like the viviparous aptera, differing in having more rhinaria (6-19) on antennal segment III, and the presence of marginal & spinal sclerites and longer hairs.

Pleotrichophorus gnaphalodes is monoecious holocyclic on various western species of sagebrush (Artemisia). It is rather widely distributed, with records in California, Colorado, Kansas, and Oklahoma, USA and in Mexico.

Other aphids on the same host

Pleotrichophorus gnaphalodes has been recorded on 7 Artemisia species (Artemisia douglasiana, Artemisia dracunculus, Artemisia longifolia, Artemisia ludoviciana, Artemisia mexicana, Artemisia stelleriana, Artemisia tridentata).

Blackman & Eastop list 36 species of aphid as feeding on Artemisia dracunculus worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 8 as occurring in Britain (Show British list).
Blackman & Eastop list 6 species of aphid as feeding on long-leaved sage (Artemisia longifolia) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 0 as occurring in Britain (Show British list).
Blackman & Eastop list 11 species of aphid as feeding on white sage, prairie sage, western mugwort (Artemisia ludoviciana) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 3 as occurring in Britain (Show British list).
Blackman & Eastop list 43 species of aphid as feeding on big sagebrush (Artemisia tridentata) worldwide, and provide formal identification keys (Show World list). Of those aphid species, Baker (2015) lists 15 as occurring in Britain (Show British list).

Acknowledgements

We are grateful to Jesse Rorabaugh for making his pictures available for use under a public domain licence.
We have used the keys and species accounts of Palmer (1952) and Corpuz-Raros & Cook (1974) along 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

Corpuz-Raros, L.A & Cook, E.F. (1974). A revision of North American Capitophorus van der Goot and Pleotrichophorus Borner (Homoptera: Aphididae). Smithsonian Contributions to Zoology 156, 1-143 (p. 55) Full text
Palmer, M.A. (1938). Additional aphids from Colorado. Annals of the Entomological Society of America 31(3), (p. 356) Abstract

Pleotrichophorus gnaphalodes

Frosted sagebrush aphid

Identification & Distribution

Other aphids on the same host

Acknowledgements

Useful weblinks

References