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Identification & Distribution

Adult apterae of Aphis loti (see first picture below) have a solid shiny black dorsal carapace, extending from the metanotum to abdominal tergite 6 inclusive (cf. Aphis lotiradicis which never has a solid dorsal carapace and varies from being entirely membranous to having transverse bands across all tergites). Autumn specimens may have the carapace reduced. The carapace shows marked reticulation. Abdominal tergites 2-6 may bear 0-2 (exceptionally 3-4) marginal tubercles (cf. Aphis lotiradicis which has a total of 6-7 marginal tubercles). The apical rostral segment is 0.8-1.1 times as long as the second hind tarsal segment. The siphunculi are roughly imbricate, often with a slight constriction just before the flange. The cauda is rather elongate finger-shaped, not uniformly tapering from base to apex (cf. Aphis craccivora,  which has the distal part tapering). The Aphis loti aptera adult body length of is 1.2-2.1 mm.

Aphis loti alates have broad separate bands across most or all abdominal tergites, extending over most of the tergite width, especially from the mid-dorsal tergites backwards. There are also large marginal and postsiphuncular sclerites. The micrograph below show an adult Aphis loti dorsal in alcohol. Note that the black dorsa of adults that have been stored in alcohol turn dark brown rather than black, because one of the dark pigments dissolves in alcohol, turning the alcohol deep purple. Stroyan (1984)  is one of many authorities who (wrongly) describes Aphis loti as being 'warm dark brown' in life, rather than shiny black. Immatures (see second picture above) are reddish brown, but appear grey-brown in life because of a light coating of powdered wax.

Aphis loti lives in the shoot apices and flowers of bird's foot trefoil (Lotus corniculatus) and kidney vetch (Anthyllis vulneraria ) (cf. Aphis lotiradicis which is found on the roots and stems of bird's foot trefoil). It is usually attended by ants, but is not tented by them (cf. Aphis lotiradicis which is tented by ants). Apterous males and oviparae with swollen hind tibiae are produced in the autumn. Aphis loti is widely distributed in Britain and continental Europe.

 

Biology & Ecology

Life cycle

Stroyan (1984)  reported that Aphis loti appears to be commoner in the western half of Britain. We have nevertheless found it commonly in East Sussex in south-east England. This is doubtless because one of its favoured hosts, bird's foot trefoil, has adapted very well to the suburban landscape, and can be found abundantly in East Sussex on roadside verges, lawns and other grassy places. In most locations a few plants will be found to support an ant-tended population of Aphis loti. The picture below shows a young nymph of Aphis loti on bird's foot trefoil.

The immatures invariably have a coating of fine wax particles turning them from red-brown to grey-brown.

The shining black adult apterae are readily distinguished from the red brown immatures.

The shining black colouration might suggest aposematic coloration given that some genotypes of bird's foot trefoil are known to contain cyanogenic glycosides (Scriber, 1978 ). However, we have noted no different behaviour of the adults vis-á-vis the immatures which would be expected if the adult colour were indeed aposematic (see for example in the aphid Uroleuon tanaceti ). Beesley (1985)  found the enzyme rhodanese in Aphis loti which is generally considered to be responsible for the detoxification of cyanide. However, Urbanska (2002)  found that rhodanese activity in another aphid, Rhopalosiphum padi was not directly associated with cyanide detoxification.

 

Ant attendance

Although Aphis loti is not considered to be an obligatory myrmecophile, we have found it nearly always to be ant-attended.

The common black garden ant (Lasius niger) is the most frequent attender (see pictures above and below).

The red ant (Myrmica ruginodis) (see picture below) also attends Aphis loti.

The red ants in the picture below were engaging in trophallaxis - namely transfer of food or other fluids amongst members of the community through mouth-to-mouth feeding (trophallaxis also applies to anus-to-mouth transfer, as in termites).

 

Natural enemies

So frequent is the ant attendance that few predators are observed attacking the colonies. However, we have found mummified aphids that have been attacked by parasitoids (see picture below).

 

Other aphids on same host:

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

  • Beesley, S.G. et al. (1985). Rhodanese in Insects. Journal of Chemical Ecology 11(1), 45-50. Abstract 

  • Scriber, J.M. (1978). Cyanogenic glycosides in Lotus corniculatus. Oecologia 34(2), 143-155. Abstract 

  • Urbanska, A. et al. (2002). Cyanide detoxifying enzymes of bird cherry oat aphid. Electronic Journal of Polish Agricultural Universities 5(2). Full text