Pineapple gall adelgid
| Pineapple gall adelgid | |
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| An opened gall, where the Adelgid nymphs are visible | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hemiptera |
| Superfamily: | Phylloxeroidea |
| Family: | Adelgidae |
| Genus: | Adelges |
| Species: | A. abietis |
| Binomial name | |
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Adelges abietis (Linnaeus, 1758) |
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| Synonyms | |
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The Pineapple gall adelgid (Adelges abietis) is a type of conifer-feeding insect that forms pineapple-shaped plant galls on its host species, commonly Norway and Sitka spruce. The adelgids (genus Adelges) are pear-shaped, soft-bodied green insects with long antennae, closely related to the aphid. "Adelges" lays up to one hundred eggs at a time, one on each needle. Adelges abietis (Linnaeus, 1758) is one of the most common species; synonyms are A. gallarum-abietis, Chermes abietis and Sacciphantes abietis.
The pineapple or pseudocone gall is a type of insect-formed gall, or abnormal outgrowth of plant tissue, that develops as a chemically induced distortion of needles, observed mostly on Norway spruce and Sitka spruce.
Prominent in appearance, the pineapple or pseudocone gall is often confused with the actual cone of the tree, due to their superficial resemblance. Pineapple galls are distinguishable by their small size, position on the base of budding twigs, and habit of the branch growing on and extending past the gall.
The pineapple gall adelgid is endemic to Europe, belonging to the 'woolly adelgid' group; it is also widely distributed in the north-eastern United States. Spruce gall aphid, eastern spruce pineapple gall adelges and eastern spruce gall aphid are alternative names. This insect belongs to the superfamily Aphidoidea, and family Adelgidae. It is the primary pest of Norway Spruce. Another similar species, the Cooley spruce gall adelgid, is indigenous to North America. This adelgid usually affects Colorado Blue, Sitka, Englemann, and Oriental spruces.
The eastern spruce gall adelgid (Adelges abietis Linnaeus) is an introduced species that feeds only on spruce. At least in 1985, the species was found in Canada from Ontario eastward and in adjacent parts of the United States.
The gall is formed from the swelling of the bases of the needles punctured by the feeding activity and activated by the saliva of the insect. The unilarval chambers are set in a woody core. The stem and needles of the host can continue growing beyond the position of the gall.
Sitka and Norway spruce are the main hosts, but A. abietis galls can be found on Colorado blue, white, and red spruces.
The yellowish green galls pass through pink and then reddish-brown colour phases. On average, they measure 1.5 to 3.0 cm in length.
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Wikipedia