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Chaitophorinae : Chaitophorus tremulae
 

 

Identification & Distribution

Chaitophorus tremulae apterae are elongate oval with the dorsum solidly blackish sclerotic, rather densely sculptured with denticular spinules (=small toothlike spines), and very often with a paler line along the mid-dorsum (see first picture below) (cf. Chaitophorus populialbae, which is greenish to yellowish white, often with small green spots, but with no dark markings). Their antennae are usually dark and half the length of the body, and the terminal process is 2.1-2.8 times as long as the base of the last antennal segment. Except in the fundatrix, abdominal tergite I is more or less completely fused with the carapace on tergites II-VI (cf. Chaitophorus leucomelas, which usually has abdominal tergite I free from tergites II-VI). The hind tibiae are without any pseudosensoria (cf. Chaitophorus populeti, which has a small number of pseudosensoria on the hind tibiae even on the adult viviparasiphunculi are dark and the legs are brown with the hind pair darker. The cauda has a distinctly knobbed apical part. The body length of Chaitophorus tremulae is 1.2-2.5 mm.

Alate Chaitophorus tremulae have very broad black dorsal abdominal cross-bands which tend to coalesce. Immatures are pale green with darker green markings.

Aspen leaf aphids live in small colonies on undersides of leaves of Aspen (Populus tremula) and a few related species of Populus. They have also been found in leaves spun together by other insects, or in leaf-nest galls made by another group of aphids (Pemphiginae). Oviparae and alate males occur in October. Chaitophorus tremulae occurs throughout Europe and as subspecies in the Far East.

 

Biology & Ecology

In Britain Stroyan (1977) describes Chaitophorus tremulae as being locally common which is also our experience. We have found it in most woodlands where aspen is common, sometimes as quite large colonies.

One feature of the picture of the alate above is the large droplet of honeydew. You can also see some smaller globules of honeydew on the leaves in some of the other pictures.

With some species the honeydew would be avidly consumed by attending ants. But honeydew of Chaitophorus tremulae has a much lower content of the sugar melizitose (Fischer & Shingleton, 2001) and is not very attractive to ants.

The colony below consisted largely of apterous adults with very few nymphs present. Although not reported elsewhere, perhaps they have a period of reproductive diapause in mid-summer.

Chaitophorus tremulae was recorded from Wales for the first time by Baker & Broad (2009). They found that the common garden ant Lasius niger ignored Chaitophorus tremulae when attending Chaitophorus populeti feeding at the same time on the same leaves. In contrast Novgorodova (2005) records Lasius fuliginosus and Myrmica rubra as attending Chaitophorus tremulae. So far none of the colonies we have found has been attended by ants.

 

Other aphids on same host

Chaitophorus tremulae have been recorded from Populus tremula, plus 7 other Populus species (Populus canescens, Populus davidiana, Populus gracilis, Populus laurifolia, Populus maximowiczii, Populus sieboldii, Populus simonii, Populus suaveolens).

 

Damage and control

Aspen is grown commercially for its wood which has a number of uses. We know of no studies that have examined the impact of aspen leaf aphid on tree growth, but its usual low numbers would make it unlikely to affect tree growth.

Acknowledgements

Whilst we make every effort to ensure that identifications are correct, we cannot absolutely warranty their accuracy. We have mostly made 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

  • Baker, E.A. & Broad, G.R. (2009). Five aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) new to Britain. British Journal of Entomology & Natural History 22, 255-263. Abstract

  • Dixon, A.F.G. & Thieme, T. (2007). Aphids on deciduous trees. Naturalist's Handbooks 29. Richmond

  • 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

  • Novgodorova, (2005). Ant-aphid interactions in multispecies ant communities: Some ecological and ethological aspects. European Journal of Entomology 102, 495-501. Full text

  • Stroyan, H.L.G. (1977). Homoptera: Aphidoidea (Part) - Chaitophoridae and Callaphidae. Handbooks for the identification of British insects. 2 (4a) Royal Entomological Society of London. Full text