InfluentialPoints.com
Biology, images, analysis, design...
Aphids Find them How to ID AphidBlog
"It has long been an axiom of mine that the little things are infinitely the most important" (Sherlock Holmes)

Search this site

Aphidinae : Macrosiphini : Nearctaphis
 

 

Genus Nearctaphis

Nearctaphis aphids

On this page: Nearctaphis bakeri

Nearctaphis [Macrosiphini]

Nearctaphis are small to medium sized aphids, mostly coloured dark green or brown. Their antennal tubercles are poorly developed, so the outline of the front of the head is almost straight. The antennae are shorter than the body length. There are no secondary rhinaria on antennal segment III in apterae, but rhinaria are present on segments II-IV (-V) in alatae. The dorsum bears quite numerous long hairs and a reticulate pattern of spicules. Apterae often have dark scleroites at the bases of hairs, sometimes fused into larger spots or cross bars. Alatae have dark marginal sclerites and dorsal cross bands which are partially or wholly joined together on tergites IV-VI to form a dark patch. Marginal tubercles may be present. The siphunculi are short and tapering and have close-set rows of small spinules (see also siphunculi in the related Anuraphis) and a well-developed flange. The cauda is short, triangular or helmet-shaped.

There are 13 or 14 species of Nearctaphis, most if not all native to the Nearctic region, although one (Nearctaphis vera) is found in Finland and north-east Russia, and another (Nearctaphis bakeri) now has a worldwide distribution. Most host alternate between Pomoidea as primary hosts and Fabaceae or Orobrachaceae as secondary hosts.

 

Nearctaphis bakeri (Short-beaked clover aphid)

Adult apterae of Nearctaphis bakeri are light greenish yellow with darker green patches, sometimes suffused with areas of orangey-pink around and anterior to the siphunculi (see first picture below). The dorsal abdomen has variably-developed dark bars on abdominal tergites V-VIII (see second adult aptera from left in second picture below) (cf. Nearctaphis californica, which has dorsal abdomen at least with complete broad dark cross-bands covering most of abdominal tergites V-VIII). All or most of the dorsal hairs arise from dark scleroites (cf. Nearctaphis crataegifoliae which has dorsal hairs mostly not arising from dark scleroites). The antennae are shorter than the body and are mostly pale apart from the apical segment which is dark. The apical rostral segment (R IV+V) is 0.10-0.13 mm long, with 2 (-3) accessory hairs (cf. Nearctaphis crataegifoliae, which has R IV+V 0.14-0.18 mm long, usually with 4 accessory hairs). The femora and tibiae are light brown with dark apices and the hind tibiae are without scent glands. The siphunculi are short tapering with close-set rows of small spinules and a well developed apical flange. The siphunculi are pale (cf. Nearctaphis crataegifoliae, which has dusky or dark siphunculi). The body length of adult Nearctaphis bakeri apterae is 1.1-2.4 mm.

First image above by permission, copyright Claude Pilon, all rights reserved
Second image above copyright Andrew Jensen under a cc-by-nc-sa licence.

Immature Nearctaphis bakeri have similar colouration to the adult apterae apart from sometimes dusky siphunculi and absence of any dorsal bands. Alatae of Nearctaphis bakeri (see second picture above) have broad dark dorsal abdominal cross-bands forming a large central patch. Their antennae bear 25-38 secondary rhinaria on segment III, 3-11 rhinaria on segment IV and 0-4 rhinaria on segment V.

In its native America Nearctaphis bakeri host alternates from its primary host (members of the apple tribe Maleae, formerly Pomoidea, in the Rosaceae) to herbaceous plants in the pea family (Fabaceae) such as Medicago, Melilotus and Trifolium (also sometimes on Capsella and Veronica). On red clover (Trifolium pratense) all parts of the plants may be colonised from the base of the stem, where populations may be ant-tented, to the flowers. Nearctaphis bakeri has been introduced (on clover?) to many other parts of the world including Europe, the Middle East and parts of Asia. These invasive populations reproduce all year parthenogenetically on the secondary hosts.

Read more...

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 sp 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

  • Blackman, R.L. & Eastop, V.F. (2006). Aphids on the world's herbaceous plants and shrubs. Vols 1 and 2. John Wiley & Sons.