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)

 

 

Chaitophorus horii beuthani

Pale willow leaf aphid

On this page: Identification & Distribution  Biology & Ecology 

Identification & Distribution:

Adult apterae of Chaitophorus horii ssp. beuthani are whitish to pale yellow. The body is rather long and narrow, with the body length 2.1-2.5 times the maximum width. Antennal segment III has only 0-4 hairs, the longest of which are only 5-20 μm long. Abdominal tergites 1-5 each have 12-30 smaller accessory hairs between the long spinal, pleural and marginal pairs. The cauda has a distinctly knobbed apex.

Alatae (not shown here) have black dorsal abdominal cross-bands.

Chaitophorus horii ssp. beuthani lives on the underside of the leaves of narrow-leaved willow such as Salix viminalis and Salix fragilis. It usually feeds from the leaf midrib.

 

Biology & Ecology:

Unlike many Chaitophorus species, the pale willow leaf aphid is never, or almost never, attended by ants (Shingleton et al., 2005 ). In this respect it is very similar to the pale sallow leaf aphid (Chaitophorus capreae ). Chaitophorus horii ssp. beuthani also resembles that species in having short mouthparts, as do other leaf feeders like Chaitophorus truncatus,  Chaitophorus tremulae,  and Chaitophorus niger. Differences in mouthpart length influence susceptibility to predation as aphids with longer mouthparts take longer to withdraw their mouthparts if disturbed.

When ant-tended, aphids increase the honeydew concentration of melezitose, a trisacharide particularly attractive to ants (Fischer and Shingleton, 2001 ). There is evidence that such adjustments incur costs to the aphids (Stadler and Dixon, 1998,  Yao et al., 2000 ), which are likely to increase if there is competition between aphid species for ant partners. Shingleton et al. (2005)  suggested that only in species feeding on deeper phloem elements will the costs of these traits be outweighed by the benefits of protection from predators.

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

  •  Fischer, M.K. & Shingleton, A.W. (2001). Host plant and ants influence the honeydew sugar composition of aphids. Functional Ecology 15, 544-550. Abstract  Full text 

  •   Shingleton, A.W. et al. (2005). The origin of mutualism: A morphological trait promoting the evolution of ant-aphid mutualisms. Evolution 59(4), 921-926. Full text 

  •  Stadler, B. & Dixon, A.F.G. (1998). Costs of ant attendance for aphids. Journal of Animal Ecology 67, 454-459.Full text 

  •  Yao, I. et al. (2000). Costs and benefits of ant attendance to the drepanosiphid aphid Tuberculatus quercicola. Oikos 89, 3-10. Full text