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"It has long been an axiom of mine that the little things are infinitely the most important" (Sherlock Holmes)

 

 

Identification & Distribution:

Adult Chaitophorus populialbae apterae are small, short-bodied, oval, greenish to yellowish white, often with small green spots (see first picture below). The head and tips of antennal segments and tarsi are light brown. The antennae are 0.6-0.9 times the length of the body, and the terminal process is 1.7-3.3 times as long as the base of the last antennal segment. The siphunculi are pale. The body length of Chaitophorus populialbae is 1.0-2.3 mm.

 

The alate (see second picture above) has the head, thorax and antennae black, and the abdomen green with dark brown cross-bands, often with bands coalescing on abdominal tergites 2-6. The pictures below are micrographs of an alatiform fourth instar nymph and an alate Chaitophorus populialbae.

 

Poplar leaf aphids live in (usually) small colonies on undersides of leaves of various Poplars (Populus spp.) and are sometimes ant-attended. Oviparae and males occur in September-November. Chaitophorus populialbae occur throughout the Palaearctic region, parts of Africa, and are introduced and widespread in North America.

 

Biology & Ecology:

Chaitophorus populialbae colonies are usually quite small and tend to be rather inconspicuous, their presence only being betrayed by the attending ants. The Myrmica ants below were remarkably static, showing none of the frenetic activity displayed, for example, by wood ants when tending large Cinara  colonies on pine trees.

Fischer & Shingleton (2001)  report that Chaitophorus populialbae has an even higher melizitose content in its honeydew than Chaitophorus populeti  (although we note the difference was not statistically significant ), which one might expect to make Chaitophorus populialbae preferred by ants. However, this may be counteracted by the fact that a species feeding on leaves (poplar leaf aphid) cannot produce as great a volume of honeydew as one feeding on stems (poplar shoot aphid). Degen et al. (1986)  showed that the daily energy intake of the weaver ant Polyrhachis simplex when feeding on honeydew of the poplar leaf aphid was 4-9 times its basic energy requirements.

The Myrmica ants tend all sizes of aphids, apparently with equal interest, with new born nymphs appearing to receive as much attention as adults, even though they clearly cannot produce as much honeydew. The image above shows an alate with a newly deposited first instar nymph attended by a Myrmica ant.

Although small colonies tend to be the rule, much larger denser colonies of what appear to be Chaitophorus populialbae can sometimes develop as shown below:

We say 'what appear to be' because it is possible that this colony is of that very variable species, Chaitophorus leucomelas.  Nevertheless the siphunculi are not dark, which would appear to rule out C. leucomelas. This large colony of mostly fourth instar was probably not being tended by ants, which were instead tending neighbouring colonies of Chaitophorus populeti. A few of a different species of ant were also foraging around the edges of the leaves for any honeydew they could find.

 

This large (ant-free) colony was characterized by large numbers of predatory midge larvae (probably Aphidoletes) which were predating the aphids. These are the bright orange larvae shown in the first picture above. An adult midge is shown is shown in the second picture laying its eggs amongst the aphid colony. One of the eggs can be seen on the aphid just to the right of the midge. An aphid mummy parasitized by a braconid parasite is also visible.

Chaitophorus populialbae is also parasitized by larval trombidid mites (see picture below).

The effect of larval trombidium mites on an individual aphid depends on the parasitic mite load and the age/size of the aphid. A single mite reduces the aphid's fecundity, but several on the same aphid may kill the host (for more information see mites on aphids. )

 

Damage and control

The poplar leaf aphid does not usually seem to be regarded as an important pest other than in relation to honeydew production on ornamental trees.

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

  •  Degen, A.A. et al. (1986). Honeydew intake of the weaver ant Polyrhachis simplex (Hymenoptera: Formicidae) attending the aphid Chaitophorus populialbae (Homoptera: Aphididae). Insectes Sociaux 33 (2), 2111-215. Full text 

  •  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 

 

Identification requests

Bashadr I. Abdullah 22/9/2014

Can you help to identify this Aphid type on Euphratic Poplar (populus spp.)?

Image copyright Bashadr I. Abdullah, all rights reserved.

Bob, Influentialpoints:

  • It is very likely that the aphid on the Populus is the poplar leaf aphid Chaitophorus populialbae (= Chaitophorus albus = Chaitophorus populialbae albus) [but] there is insufficient detail on the photo to check some of the identification features.

    To be absolutely certain about our identification we would need close-up photos with higher resolution so we could better examine the morphological characters.

    For example in Chaitophorus populialbae the terminal process of the antenna is 2.6-3.3 times as long as the base of the last antennal segment. You need very close up pictures to be able to check if this is the case.

    However, the colour of the aphids (light green with darker green spots), the overall length of the antennae (which are just visible in your photos) and the fact they are on poplar, all point towards Chaitophorus populiabae.