Biology, images, analysis, design...
|"It has long been an axiom of mine that the little things are infinitely the most important" |
Green-striped spruce aphidOn this page: Identification & Distribution Biology & Ecology Other aphids on the same host Damage & Control
Identification & Distribution:Apterae of Cinara piceicola have a dark brown head and thorax and pale olive-buff abdomen. In life there are two longitudinal faint greyish-green dorsal stripes and a thin white wax stripe between them (see first picture below). The dorsum is not wax powdered, but the underside of the body is mealy. The abdomen of the aptera has sclerotized areas on the dorsum consisting of a transverse segmented band on segments I-III and a broad cross band on VIII (see first picture below and first micrograph below that). A key distinguishing characteristic of Cinara piceicola is that the hairs on the outer side of the hind tibiae are all short - less than 0.12 mm long (cf. most other spruce feeding aphids in which all, or many, of those hairs are long, often greatly exceeding 0.12 mm.) The siphuncular cones are usually small and rather faintly pigmented (cf. Cinara pruinosa which have prominent black siphuncular cones). The body length of the adult aptera is 2.1-4.2 mm.
Beware: Cinara piceicola often form mixed species colonies with Cinara pruinosa so, to distinguish them, look carefully at the length of hairs on the tibia and the colour of siphunculi on adults.
The second micrograph below is a ventral view of an aptera showing the long rostrum.
Cinara piceicola occurs on spruce (Picea species), especially Norway spruce, in colonies on bark of woody shoots between needle-bases in spring. They move to older branches and roots in summer. Numerous alatae are produced in May-June. Oviparae and apterous males occur from July onwards. Cinara piceicola is found in north, west and central Europe, and apparently China.
Biology & Ecology:
Cinara piceicola overwinters as eggs which are laid singly on spruce needles in October and November. The eggs are yellow when first laid, soon turning a mealy grey colour as shown in the images below. Up to three eggs may be laid on one needle.
The eggs hatch in spring to give the fundatrices, which feed on the bark of woody shoots between needle-bases. The picture below is of a heavily pigmented mature Cinara piceicola fundatrix.
The fundatrices produce large numbers of progeny which feed on the underside of lignified shoots
From late May to July alatae are produced which disperse and then start colonies on the current year's growth
Sexual morphs develop in the autumn. The picture below shows a male and two oviparae of Cinara piceicola.
The ovipara is greyish or orange-brown, and has a prominent pericaudal wax ring. Males are wingless, small (only 2.5 - 3.0 mm), dark green, elongate and flattened.
Cinara piceicola is nearly always attended by ants and was decribed by Binazzi & Scheurer (2009) as being compulsorily dependent on ants.
The pictures above and below show them being attended by southern wood ants (Formica rufa).
We have most frequently seen Cinara piceicola being attended in coniferous woodland by Formica rufa, and Carter & Maslen (1982) noted that in nearly all instances colonies had been found to be attended by wood ants. But they are not totally dependent on that species.
For several years we had a thriving population of the green-striped spruce aphid on a replanted Norway spruce in our garden. There they were attended by the common black garden ant Lasius niger.
Johansson & Gibb (2012) compared the quality and quantity of honeydew harvested by ants among clear-cuts, middle-aged and mature spruce-dominated stands in boreal forests in Sweden. Clear cuts had 5-10 retention trees per hectare. Aphid populations were dominated by Cinara piceicola. Clear cutting was shown to contribute to a reduction in size and abundance of wood ant workers and mounds. The presence of ants is known to reduce predation, but not apparently parasitism. Indeed Völkl & Novak (1997) showed that the aphid parasitoid Pauesia pini laid more eggs in ant-attended hosts than in those unattended.
Other aphids on same host:
Blackman & Eastop list about 170 species of aphids as feeding on spruces (Picea) worldwide, and provide formal identification keys.
Damage and control
There is little or no information available on damage caused by the green-striped spruce aphid. In Europe its presence is generally welcomed as a source of honeydew for bees, which produce excellent honey when feeding on the honeydew.