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Cinara apini

Spotted short-haired limber pine aphid

On this page: Identification & Distribution Biology & Ecology Other aphids on the same host Damage & Control

Identification & Distribution

Adult apterae of Cinara apini are described as dark brown mottled with wax powder on spinal and marginal areas and intersegmentally (cf. Cinara flexilis, which has no wax powder on the dorsum). Our pictures suggest that dorsum may also have patches of chestnut brown. The appendages are mainly yellowish to dusky, apart from the distal two-thirds of the tibiae which are black. The hairs on the hind tibia are rather spine-like, and those on the dorsal side are less than 0.5 times as long as half the diameter of the tibia (cf. Cinara villosa which has the hairs on the hind tibia finer and more numerous, 0.6 to 1.5 times the diameter of the tibia). The second hind tarsal segment is less than 1.5 times the length of the penultimate rostral segment (RIV). The siphuncular cones are dark, with the diameter of the siphuncular cone greater than the length of the second hind tarsal segment (HTII) (cf. Cinara flexilis, which has the diameter of the cone less than half the length of HTII). The body length of adult Cinara apini apterae is 3.2-4.0 mm.

Images reproduced by permission copyright Chen et al., all rights reserved.

The colour of Cinara apini alate females (see third picture above) is dark brown to black on the head and thorax, reddish-brown on the abdomen, with a light wax covering on the head and thorax.

Note:
Another species, Cinara villosa, also occurs on bark of Pinus flexilis twigs in western North America, and is indistinguishable from Cinara apini apart from having longer hairs on the tibiae. Cinara villosa occurs in some of the same localities and on the same host, but not mixed in the same colonies or on the same tree (Palmer, 1952). Cinara villosa was originally described as a long-haired form of Cinara apini in Colorado, but subsequently given full species status as Cinara villosa. Dr Andy Jensen (pers. comm.) reports that short and long haired forms were present in the specimens that were photographed on this page, so the images show Cinara apini and/or Cinara villosa. It is possible (or even likely) that Cinara apini and Cinara villosa are not distinct species.

Cinara apini feeds on the small branches in the periphery of the crown of limber pine (Pinus flexilis) where they form large dense colonies. There is also one record from whitebark pine (Pinus albicaulis). Oviparae and alate males occur in September-October, and eggs with a light covering of wax-wool are laid on the needles. Cinara apini is found in western North America, both in Canada and the USA.

 

Biology & Ecology

We are indebted to students of the University of California (Charles Chen, Lori Liu, & Skai Peterson) for the excellent pictures of Cinara apini and their attending ants shown below. Their field work was done in Inyo National Forest on limber pines (Pinus flexilis) (see brief video showing Pinus flexilis and other plants in Inyo National Forest). Their research is reported in Chen et al. (2018).

Colour

The images we have shown above match closely with the species description of Palmer (1952) as do the images directly below - in other words dark brown mottled with wax powder.

Images reproduced by permission copyright Chen et al., all rights reserved.

However, a number of adult apterae had the dark brown replaced to a lesser or greater extent by reddish-brown.

Images reproduced by permission copyright Chen et al., all rights reserved.

Immatures were similarly reddish especially on the posterior segments, also often with two longitudinal faint greyish-green dorsal stripes (see pictures below).

Images reproduced by permission copyright Chen et al., all rights reserved.

Chen et al. (2018) recorded an apparent feeding-site difference between the colour forms, with the red-brown form occurring more on shoot tips, and the dark brown/black form on branches. On this basis, as well as other behavioural differences, Chen et al. concluded there were two species present, the dark brown form (Cinara apini) and the red form (an 'unknown Cinara species'). There is no suggestion that the variation in hair length recorded by Jensen (see above) was related to the presence of two colour forms - certainly if the long-haired form is Cinara villosa, its appearance is supposedly indistinguishable from Cinara apini apart from its longer tibial hairs (Palmer 1952).

Ant attendance

Jones (1927) reported a large number of different species of ants attending Cinara apini on Pinus flexilis - Camponotus heracleanus, Formica comata, Formica dakotensis, Formica subsericea (as Formica fusca), Formica aserva (as Formica sanguinea ssp. subnuda), Formica truncicola, Lasius niger and Myrmica rubra.

Bradley (1961) reported three species of ants attending Cinara apini in Canada - Formica subsericea (as Formica fusca), Formica subnuda and Lasius alienus.

Chen et al. (2018) reported several different species of ants, identified as silver, black, red and brown, tending Cinara apini (and related species) on limber pine.

The ant species in the picture below, possibly Formica subsericea, was referred to as the 'silver ant'.

Image reproduced by permission copyright Chen et al., all rights reserved.

The ant species in the picture below was referred to as the 'black ant'.

Image reproduced by permission copyright Chen et al., all rights reserved.

The ant species in the picture below was referred to as the 'red ant'.

Image reproduced by permission copyright Chen et al., all rights reserved.

The ant species in the picture below, most likely a Formica species, was referred to as the 'brown ant'.

Image reproduced by permission copyright Chen et al., all rights reserved.

Chen et al. (2018) carried out a number of investigations on the ant-aphid interactions. On the ant-aphid association, silver ants, red ants, and black ants largely associated with Cinara apini, whereas brown ants typically associated with 'red aphids' (their unknown species). On ant defensive behaviour, brown ants were the most aggressive in defending their aphids and black ants defended least actively. Clusters guarded by red and brown ants moved more frequently than those guarded by other ants.

 

Other aphids on the same hosts

 

Damage and control

There is no information in the literature about any damage to pine trees caused by Cinara apini.

Acknowledgements

We thank Charles Chen, Lori Liu, & Skai Peterson, all students of the University of California, for their pictures of Cinara apini and their attending ants at Inyo National Forest, California, USA.

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

  • Bradley, G.A. (1961). A study of the systematics and biology of aphids of the genus Cinara in Canada. PhD thesis, McGill University, Montreal, Canada. Full text

  • Chen, C., Liu, L. & Peterson, S. (2018). Formica ant and Cinara aphid mutualisms on limber pines (Pinus flexilis). California Ecology & Conservation Research. Full text

  • Jones, C.R. (1929). Ants and their relation to aphids. Colorado Experiment Station Bulletin 341 1-96. Full text

  • Palmer, M.A. (1952). Aphids of the Rocky Mountain Region: including primarily Colorado and Utah, but also bordering area composed of southern Wyoming, southeastern Idaho and northern New Mexico. Full text