Threats

Green Pine Aphid / Eulachnus rileyi

Green Pine Aphid / Eulachnus rileyi
Eulachnus rileyi (Williams)

Lachnus rileyi (Williams)

Eulachnus bluncki (Börner)

Eulachnus tauricus (Bozhko)

Protolachnus bluncki

Protolachnus rileyi

Eriosoma rileyi (Williams)

Sap sucking

Green pine aphids feed on the underside of pine needles growing at the crown of the tree (Chilima 1991). Infestations cause the needles to turn yellow and under high infestations the growth of the tree is stunted. Infestations on stressed trees can lead to top die-back or even tree death in extreme cases. Sooty mould can grow on the honey dew excreted by the aphids feeding on the sap and this can give the needles a look of being covered in black precipitate (Murphy et al. 1991).

 

Apterous Vivipara (wingless parthenogenetic form): A dark body and black legs. It is approximately 2 to 2.6 mm long and 0.6 mm wide. The cornicle (one of two backward-pointing tubes on the dorsal side of the abdomen) consists of a ring but does not have a conical base. The cauda (last segment of the abdomen) is usually rounded but with an upturned tip, which, when extended, appears pointed.

Alate Vivipara: This form is the same size and colour as the apterous vivipara. The secondary antennal sensoria (used as an olfactory sensor for initial host location) are absent on segment three and there is one on segment four. The hairs are heavy, 0.1 mm long, spike-like on the vertex (area behind the compound eyes on the head), sparse and inconspicuous on the body, and moderately numerous on the appendages. The lengths of the hairs on the hind tibia are at least twice the diameter of the tibia. The rostrum is broad and obtuse. The forewing has a faint media that is usually forked once.

Apterous Ovipara: The apterous ovipara is similar in appearance to the apterous vivipara except that the hind tibia is 1.3 to 1.65 mm long with the proximal half moderately swollen and rather thickly covered with flat sensoria.

Alate Male: This stage is similar in appearance to the alate vivipara except for the antennae, which are much longer (approximately 1.75 mm). In addition, the sensoria are numerous on segments three and four.

The pine needle aphid exhibits cyclic reproduction. This consists of altering sexual and asexual generations. The egg stage has an overwintering period. The eggs hatch in the summer and produce stem mothers which reproduce parthenogenetically and vivarously (bringing forth live young). The subsequent generations are known as the viviparae. These generations consist of apterous (wingless) and alate (winged) females. In the summer they reproduce parthenogenetically. The sexual stage usually appears at the end of summer and consists of a true apterous female and males that can be apterous or alate. This final generation of females is oviparous and lays eggs, which remain dormant until the following spring (Palmer 1952).

Studies conducted in Africa (introduced) indicate the species has a reduced life cycle and may reproduce throughout the years without a sexual generation. All life stages feed on the underside of pine needles (Murphy et al. 1991)

The braconid parasitoid, Diaeretus leucopterus, has been considered as a potential biological control agent for Eulachnus sp. (Murphy & Völkl 1996) together with Entomopthora planchoniana Cornu, an entomogenous fungus (Katerere 1983). 

1978.
Mpumalanga, Kwazulu-Natal, and Limpopo, Northern Province.
Pinus spp.
Europe

Gallery

CABI. 2014. Eulachnus rileyi (Williams), pine needle aphid.[pest/pathogen]. Eulachnus rileyi (Williams), pine needle aphid.[pest/pathogen]., (AQB CPC record).

Chilima, CZ .1991. The status and development of conifer aphid damage in Malawi. Workshop Proceedings. Exotic aphid pests of conifers: a crisis in African forestry, Muguga, Kenya: Kenya Forest Research Institute and Food and Agriculture Organization of the United Nations, 64-67.

Katerere, Y. 1983. The fungus Entomophthora planchoniana Cornu (non Thaxter) the pine needle aphid, Eulachnus rileyi (Williams) Zimbabwe. The Commonwealth Forestry Review 1, 271-273.

Murphy, ST., Abraham, YJ., Cross, AE .1991. Ecology and economic importance of the aphid pests, Pinus sp. and Eulachnus rileyi on exotic pine plantations in southern and eastern Africa. In: Ciesla WM, Odera J, Cock MJW, eds. Workshop Proceedings, Exotic aphid pests of conifers: A crisis in African forestry. Mugaga, Kenya: Kenya Forest Research Institute and Food and Agriculture Organization of the United Nations, 48-53.

Murphy ST., Völkl W. 1996. Population dynamics and foraging behaviour of Diaeretus leucopterus (Hymenoptera: Braconidae), and its potential for the biological control of pine damaging Eulachnus spp. (Homoptera: Aphididae). Bulletin of Entomological Research 86, 397-405. Palmer, MA, 1952. Aphids of the Rocky Mountain Region. Colorado, USA: The Thomas Say Foundation.

Palmer, Miriam A. 1952 Aphids of the Rocky Mountain region. In: Palmer MA. Aphids of the Rocky Mountain Region.