Cinara confinis

Identification & Distribution:

Apterae of Cinara confinis are greenish-black (see first picture below) or dark brown, with a double row of blackish slightly shining speckles and small flecks of fine wax in transverse rows. The head and thoracic plates are dark brown, with some wax markings on the thoracic plates. The length of the sclerotized part of the stylet groove is greater than 1.8 mm. The antennae of Cinara confinis are pale yellowish-grey with a darkening of each segment distally. The length of the fifth antennal segment, including the terminal process, is clearly longer than the fourth antennal segment. The tibiae are only slightly bowed (cf. Cinara curvipes in which the tibiae are noticeably long and bowed). The femora and tibia either have dark brown annulations or are mainly black, and the tarsi are black. The siphuncular cones are dark and prominent (cf. Cinara pectinatae which has small pale siphunculi). The body length is 3.8-7.8 mm

Micrographs of clarified mounted aptera & alate courtesy Favret, C. & G.L. Miller, AphID. Identification Technology Program, CPHST, PPQ, APHIS, USDA; Fort Collins, CO.

Cinara confinis feeds on the stems and twigs, rarely on the roots, of many fir (Abies) species, and sometimes on Himalayan cedar (Cedrus deodora). It has a holarctic distribution and is recorded from Europe, much of Asia, North America (formerly known as Cinara grossa) and Argentina. Carter & Maslen (1982) describe it as of sporadic occurrence in Britain occurring in northern Scotland, west of Ireland and southern England.

Biology & Ecology:

Life cycle

Struble et al. (1976) describe the biology of Cinara confinis (under the name Cinara abieticola) in Maine, USA. Fundatrices were first found in May at the bases of buds. Resultant colonies were generally located on the trunk just below the first whorl of branches, as shown in the picture below for a colony in Sussex, UK.

Parthenogenetic reproduction combined with viviparity means that colonies can build up rapidly.

Colonies can reach an enormous size especially on trees in urban areas where natural predators are lacking.

Colonies disperse rapidly if disturbed. Apterous females tend to drop off but nymphs move rapidly up or down the stem and on to the branches. The picture below shows a dispersing nymph moving away from a disturbed colony.

In Maine, colonies on fir trunks declined by mid June as aphids moved to root collar and roots. Movement to tree roots in summer has only rarely been recorded in Britain (Carter & Maslen (1982)). Winged males and oviparae can be found in October, and the aphid overwinters in the egg stage.

Colour

Cinara confinis is one of a number of aphid species which has (apparently) aposematic coloration in the adults, but cryptic coloration in the nymphs (see also aphid color). The first picture below shows a metallic dark green adult aptera of Cinara confinis patterned with white wax.

The green sheen is sometimes much less in evidence, and the adult is instead dark brown (see picture below).

We have found a single alate which was cryptically coloured, varying from grey to grey green with white wax markings (see picture below).

Immatures are cryptically coloured with classic disruptive camouflage (see picture below).

Ant attendance

Binazzi & Scheurer (2009) report that Cinara confinis is optionally dependent on ant attendance. This species sometimes occurs in special earth galleries constructed by ants on the bark of fir trees (Wood-Baker, C., 1964). All the colonies we have found have been strongly attended, mostly by southern wood ants (Formica rufa).

In 2018 we found colonies of Cinara confinis on young Abies trees attended not by Formica rufa, but instead by Lasius fuliginosus (see picture below).

Natural enemies

On one occasion several of the colony had been parasitized despite the presence of ants. The resultant aphid mummies were blue-black and two are shown below along with a live unparasitized adult.

The adult parasitoid is shown below (first), with an enlargement of the head and antennae (second).

Given the extraordinary number of antennal segments (Baker, pers. comm.), this parasitoid is almost certainly Pauesia grossa. This species is a parasitoid specific to Cinara confinis, but it has not been previously recorded in UK. Few predators have been observed around Cinara confinis colonies, although Struble et al. (1976) reported larvae of Metasyrphus medius in June.

Other aphids on same host:

• Blackman & Eastop list 47 species of aphid as feeding on true firs (Abies species) worldwide, and provide formal identification keys (Show World list).

  Of those aphid species, Baker (2015) lists 11 as occurring in Britain (Show British list).

• Blackman & Eastop list 7 species of aphid as feeding on Himalayan cedar, deodar cedar (Cedrus deodora) worldwide. (Show World list). Of those Baker (2015) lists 5 aphid species as occurring in Britain (Show British list).

Damage and control

Although Cinara confinis is still rare in Britain, it can occur in enormous numbers on large fir and cedar trees grown for their amenity value in urban areas of the USA. With large infestations, the tendency of the aphids to wander about a lot means they can cause a public nuisance - which is accentuated by the honeydew deposits, sooty moulds and abundant wasps.

The image above is of an Abies amabilis (Pacific silver fir) found infested with Cinara confinis at Bedgebury Pinetum, UK.

Acknowledgements We are grateful to the UK Forestry Commission, Bedgebury Pinetum, for their kind assistance. 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 Binazzi, A. & Scheurer, S. (2009). Atlas of the honeydew producing conifer aphids of Europe. Aracne. 132 pp. Introduction Carter, C.R. & Maslen, N.R. (1982). Conifer Lachnids. Forestry Commission Bulletin No. 58, 75pp. Strubble, D.B. et al. (1976). Notes on the biology of Cinara abieticola (Chlodkovsky) in Maine and descriptions of sexuales (Homoptera: Aphididae). Entomological News 87, 280-284.Abstract Wood-Baker, C. (1964). Records of sixty-six European and British aphids. (Hem., Aphididae). Entomologist's Monthly Magazine 100, 43-48.