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Chaitophorus horii beuthani
Pale willow leaf aphidOn this page: Identification & Distribution Biology & Ecology Other aphids on the same host
Identification & Distribution:
Adult apterae of Chaitophorus horii ssp. beuthani are whitish to pale yellow with no distinct dorsal abdominal markings (cf. Chaitophorus truncatus, which has either has three dark green longitudinal stripes, or is solidly blackish on the dorsum; also cf. Chaitophorus salijaponicus niger, which is usually blackish-brown). Antennal segment III has only 0-4 hairs, the longest of which are only 5-20 μm long. The body is rather long and narrow, with the body length 2.1-2.5 times the maximum width (cf. Chaitophorus capreae, which has a body length 1.8-2.1 times the maximum body width). 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.
Chaitophorus horii beuthanialatae (not shown here) have black dorsal abdominal cross-bands.
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 beuthani also resembles that species in having short mouthparts, as do other leaf feeders like Chaitophorus truncatus, Chaitophorus tremulae, and Chaitophorus salijaponicus 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.
Other aphids on same host:
Chaitophorus horii beuthani has been recorded from 12 Salix species (Salix babylonica, Salix ×calodendron , Salix caprea, Salix cinerea, Salix fragilis, Salix incana, Salix lapponum, Salix lasiolepis, Salix purpurea, Salix ×smithiana, Salix triandra, Salix viminalis).