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Identification & Distribution

Adult apterae of Aphis coreopsidis (see first two pictures below) are yellow with a variable degree of dark green mottling especially along the spinal area. There is sometimes an orange suffusion around and between their siphunculi. The head and antennal segments I, II, and the basal part of III, are very pale, contrasting with the rest of the antenna which is dark. The antennal terminal process is 4 or more times as long as the base of antennal segment VI. Their legs are mostly pale-dusky, but the apical parts of the tibiae are somewhat darker. The siphunculi are dark, about twice as long as the cauda, and 0.24-0.40 times the body length. The cauda is longer than broad and much paler than the siphunculi. The body length of adult Aphis coreopsidis apterae is 1.5-1.8 mm.

First image above by permission, copyright Claude Pilon, all rights reserved.
Second and third images above, copyright glmory under a public domain (CCO) licence.

The alate viviparous Aphis coreopsidis female (see third picture above, and second below) is pale green heavily mottled with dark green with a dark head, thorax, antennae, legs and siphunculi. The ovipara is small and yellowish-green. The alate male has the head and thorax dark greenish brown, the abdomen dark green, siphunculi and cauda brownish and antennae brown; antennal segments III & IV have scattered secondary sensoria but on segment V they are arranged in an irregular row.

First image above copyright glmory under a public domain (CCO) licence.
Second image above copyright CBG Photography Group under a Creative Commons Zero (CC0) license.

Aphis coreopsidis lives on the stems and leaves of new shoots of the tupelo tree (Nyssa sylvatica) in spring. In North America it host alternates between Nyssa and secondary hosts in the aster family (Asteraceae), especially blackjack (Bidens pilosa), also mallows (Malvaceae) and mints (Lamiaceae). On its summer hosts Aphis coreopsidis occurs on the undersides of leaves and on the flower stalks. They are usually attended by ants. Sexual forms develop on Nyssa in autumn. The oviparae are small (1.1-1.2 mm) and yellowish-green, whilst the males are alate, about 1 mm in body length, dark green and brown (see Hottes & Frison, 1931). The fundatrices on the primary host are still undescribed. Populations have been found especially on Bidens pilosa in central and South America and Hawaii, and alatae appearing to be this species have been trapped in Ghana, Uganda and Saudi Arabia.

 

Biology & Ecology

Life cycle

Aphis coreopsidis overwinters in the egg stage on the tupelo tree (Nyssa sylvatica). In spring the eggs hatch, and aphid colonies develop on the leaves and stems of the tree (see picture below).

Image above copyright Rob Curtis under a Creative Commons Attribution-Share Alike license.

As can be seen above, Aphis coreopsidis may completely encircle the apical portions of the stems for several inches. In late spring winged forms develop which migrate to the secondary hosts, in this case members of the aster family (Asteraceae), mallow family (Malvaceae) and mint family (Lamiaceae) where the species remains for the summer. In autumn, winged forms develop which migrate back to the primary host. The picture below shows an immature winged form with wing buds.

Image above by permission, copyright Claude Pilon, all rights reserved.

Sexual forms then develop, and the female lays overwintering eggs on the tupelo tree.

Ant attendance

Nielsson et al. (1971) recorded the following ant associations with Aphis coreopsidis:

  • On blackjack (Bidens pilosa): Camponotus abdominalis floridanus.

  • On groundsel bush (Baccharis halimifolia): Crematogaster ashmeadi, Crematogaster atkinsoni, Dolichoderus pustulatus, Solenopsis molesta, Solenopsis saevissima richteri and Solenopsis sp.

  • On an unspecified host: Conomyrma pyramicus.

In addition, Lasius americanus has been observed attending Aphis coreopsidis on white snakeroot (Ageratina altissima) in Bucks Co, Pennsylvania, USA (see images by Bill Keim).

The ants in the picture below attending Aphis coreopsidis on white snakeroot also appear to be a Lasius species.

Image above by permission, copyright Claude Pilon, all rights reserved.

Renault et al. (2005) looked at the interaction between the aphid Aphis coreopsidis and the ant Camponotus sp. on blackjack. Population growth of Aphis coreopsidis was greater on plants where ants were present than on ant-excluded plants. The density of aphids on was positively correlated with the density of attending ants. This was apparently because the Camponotus ants reduced the number of spiders on the plants, which had been predating the aphids.

Image above copyright glmory under a public domain (CCO) licence.

As a result of these interactions, plants with ants had a significantly lower quantity of viable seeds than those without ants.

 

Other aphids on the same host

Primary host

Aphis coreopsidis has been recorded from one species of Cornaceae (Nyssa sylvatica).

Secondary hosts

Aphis coreopsidis has been recorded from 9 species within the Bidens genus (Bidens aristosa, Bidens bipinnata, Bidens connata, Bidens frondosa, Bidens pilosa, Bidens reptans, Bidens subalternans, Bidens tripartita, Bidens vulgata) - plus a variety of other Compositae / Asteraceae (Ageratina altissima, Baccharis halimifolia, Baccharis pilularis, Baccharis salicifolia, Baltimora recta, Brickellia grandiflora, Cosmos spp., Coreopsis lanceolata, Mikania micrantha, Parthenium hysterophorus, Solidago caesia, Sonchus oleraceus, Spilanthes urens, Symphyotrichum laevi, Vernonia scorpioides and possibly Chaptalia nutansa and a Eupatorium spp.).

It has also been recorded from Lamiaceae (Blephilia hirsuta, Nepeta cataria), Malvaceae (Hibiscus rosa-sinensis, Sida spp.), Amaranthaceae (Iresine spp.) and possibly Nyctaginaceae (Boerhavia erecta).

Acknowledgements

We are especially grateful to Claude Pilon for pictures of Aphis coreopsidis (for more of her excellent pictures see). We are also grateful to Jesse Rorabaugh (glmory) for the pictures of Aphis coreopsidis that he has made available to everyone under a 'public domain' (CC0) licence (for more of his excellent pictures see).

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 have supplemented this with information from Hottes & Frison (1931). 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

  • Hottes, F.C. & Frison, T.H. (1931). The Plant Lice, or Aphiidae, of Illinois. Illinois Natural History Survey Bulletin 19(3), 123-447. Full text

  • Nielsson, R.J. et al. (1971). A preliminary list of ants associated with aphids in Florida. The Florida Entomologist 54(3), 245-248. Full text

  • Renault, C.K. et al. (2005). An aphid-ant interaction: effects on different trophic levels. Ecological Research 20(1), 71-74. Abstract