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Green-striped spruce aphidIdentification & Distribution Biology & Ecology 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 stripe between them. The dorsum is not wax powdered but the underside of the body is mealy. The siphuncular cones are usually small and rather faintly pigmented. The body length is 2.1-4.2 mm.
The first picture above shows an adult aptera of Cinara piceicola feeding on the stem in June. Note especially the two faint dorsal green bands, with a rather indistinct whitish line between them. The second picture above shows an alate vivipara feeding on spruce. It is similar in appearance to the apterous vivipara.
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. These sclerotized areas are visible in the first micrograph below of an aptera in alcohol. The second micrograph is a ventral view of an aptera showing the long rostrum.
A key distinguishing characteristic of Cinara piceicola from most other spruce feeding aphids is that the hairs on the outer side of the hind tibiae are all less than 0.12 mm long. In other species all or many exceed 0.12 mm. The ovipararous female is rather small (at least compared to the vivipara) and is greyish or orange-brown. In life the ovipara has a prominent pericaudal wax ring (see below).
Cinara piceicola occurs on spruce (Picea spp.), 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. They are yellow when first laid, soon turning a mealy grey colour as shown in the image below. Up to three eggs may be laid on one needle.
The eggs hatch in spring, and the nymphs form colonies on the bark of woody shoots between needle-bases as can be seen in the first picture below.
The two characteristic green lines on the dorsum are somewhat brighter on nymphs (see first picture above) than on the adult which facilitates identification of colonies in the field.
The picture below is what appears to be a Cinara piceicola fundatrix.
Cinara piceicola is nearly always attended by ants and was decribed by Binazzi & Scheurer (2009) as being compulsorily dependent on ants. The picture below shows them being attended by southern wood ants (Formica rufa).
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.
Sexual morphs develop in the autumn. The picture above shows a male and two oviparae (egg laying females) of Cinara piceicola. The wingless male is small (only 2.5 - 3.0 mm), dark green, elongate and flattened. The second picture above of an ovipara in alcohol shows the reduced level of sclerotization on the dorsum of the ovipara..
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.