Cryphalus Abietis
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''Cryphalus abietis'' is a small bark beetle (subfamily
Scolytinae A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although th ...
, family
Curculionidae The Curculionidae are a family of weevils, commonly called snout beetles or true weevils. They are one of the largest animal families with 6,800 genera and 83,000 species described worldwide. They are the sister group to the family Brentidae. Th ...
), around 1.6 mm long, that is widely distributed in Europe. It infests mainly
spruce A spruce is a tree of the genus ''Picea'' ( ), a genus of about 40 species of coniferous evergreen trees in the family Pinaceae, found in the northern temperate and boreal ecosystem, boreal (taiga) regions of the Northern hemisphere. ''Picea'' ...
trees (''Picea''), but also other conifers. Like closely related species, e.g. ''
Cryphalus saltuarius ''Cryphalus saltuarius'' - ''Cryphalus asperatus'' is a small bark beetle (subfamily Scolytinae, family Curculionidae), around 1.8 mm long, that infests mainly spruce trees (''Picea''), less often other conifers. It has been recorded mainly ...
'', ''C. abietis'' attacks primarily weakened and freshly dead branches of its host trees, and usually does not kill trees.


Taxonomy

While ''C. abietis'' is well known in the German literature, its taxonomy has been often confused elsewhere due to its similarity with ''
Cryphalus saltuarius ''Cryphalus saltuarius'' - ''Cryphalus asperatus'' is a small bark beetle (subfamily Scolytinae, family Curculionidae), around 1.8 mm long, that infests mainly spruce trees (''Picea''), less often other conifers. It has been recorded mainly ...
'', the destruction of its type specimens during World War II, and a statement by Wood in 1972 that it is a synonym of ''Cryphalus asperatus''. For example, Justesen et al. provided detailed descriptions of ''C. abietis'' and its biology under the name "''Cryphalus asperatus'' (Gyllenhal, 1813), syn. ''Bostrichus abietis'' Ratzeburg, 1837". However, the authors clarified in a subsequent publication that ''Cryphalus abietis'' is a separate species and that ''Cryphalus asperatus'' and ''Cryphalus saltuarius'' are synonyms. Therefore, in some publications, the name ''Cryphalus asperatus'' needs to be replaced by ''Cryphalus abietis''. For more details see the taxonomy section of ''
Cryphalus saltuarius ''Cryphalus saltuarius'' - ''Cryphalus asperatus'' is a small bark beetle (subfamily Scolytinae, family Curculionidae), around 1.8 mm long, that infests mainly spruce trees (''Picea''), less often other conifers. It has been recorded mainly ...
''.


Distribution

''C. abietis'' has been reported from nearly all European countries, but is absent from the most northern region of Norway, Sweden, Finland and Russia. In addition, records from northern Africa, western Asia and far eastern Asia are uncertain, due to the presence of very similar species.


Description

The adult beetle of ''C. abietis'' is between 1.4 and 1.9 mm long, average 1.6 mm, and 2.3× longer than wide. The color is dark brown to black, but the base of the antennae and parts of the legs are lighter brown. The pronotum is domed, covered with tiny humps (also called 'asperities') on its anterior slope bordering the head. The elytra have longitudinal stripes or grooves with rows of punctures. Morphologically, ''C. abietis'' is very similar to ''
Cryphalus saltuarius ''Cryphalus saltuarius'' - ''Cryphalus asperatus'' is a small bark beetle (subfamily Scolytinae, family Curculionidae), around 1.8 mm long, that infests mainly spruce trees (''Picea''), less often other conifers. It has been recorded mainly ...
'', both species may overlap in some features and can be confused. However, ''C. abietis'' is on average smaller and the longitudinal grooves on the elytra are usually clearer, deeper and wider. Both species can be reliably separated by the size and shape of the male aedeagus and by their DNA structure.


Biology

Spruce species are the main host plants, in particular, Norway spruce (''
Picea abies ''Picea abies'', the Norway spruce or European spruce, is a species of spruce native to Northern Europe, Northern, Central Europe, Central and Eastern Europe. It has branchlets that typically hang downwards, and the largest cones of any spruce, ...
''), other ''Picea'' species like ''P. obovata'' or ''P. orientalis'' and some fir species like ''Abies procera'' are also important hots. Pine species and some other conifers can be also infested. Preferably, branches with a thin bark are attacked. Freshly dead branches are also infested. Often the attack starts at the axil of a shoot. However, the damage caused by ''C. abietis'' seems to be rarely significant. Some reports of young trees being destroyed or weakened by the beetle could have been associated with seedlings being damaged during transport. ''C. abietis'' may overwinter as adult beetle, larva or pupa. According to Ratzeburg it is the earliest bark beetle in Germany and emerges already when there is still snow. Males and females aggregate on suitable branches and after mating construct a large nuptial chamber under the bark, where the female deposits around 20 eggs. The developing larvae construct closely spaced galleries that radiate from this chamber and are 2–4 cm long. There is typically one generation per year in cooler parts of Europe, but two in southern parts (spring to early summer and summer to autumn).


References

{{Taxonbar, from=Q1499187 Scolytinae Beetles described in 1837 Beetles of Europe Taxa named by Julius Theodor Christian Ratzeburg