Nordic coconut weevil
| Nordic coconut weevil | ||||||||||||
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Nordic coconut weevil ( Limobius borealis ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Limobius borealis | ||||||||||||
| ( Paykull , 1792) |
The Nordic coconut weevil ( Limobius borealis ) is a weevil from the subfamily Hyperinae . The 2.5 to three millimeters long insect lives on different species of the family of geraniaceae .
The species is listed in the Red Lists of North Rhine-Westphalia under category 2 (rare species, tied to certain biotopes, endangered to be assumed). In Saxony-Anhalt it is extremely rare and potentially endangered.
Notes on the name
The first description occurs in 1792 under the name Curculio borealis by the Swede Paykull . Paykull adds to his description of the species: habitat in Muonioniska Bothniae occidentalis (Latin: lives in Muonioniska in western Bothnia (village on a river in Lapland )). He mentions the location of the specimen on which the first description is based. That is why he chooses the species name boreālis ( lat. North) with reference to weevils in Sweden , although this name does not do justice to the range of the species. The name part "nordisch" of the German name is the transfer of borealis , the name part cocoon weevil refers to the fact that the larvae pupate in a cocoon.
The species or local varieties have been described several times, the names exist for them:
- Phytonomus fumipes Curtis 1840
- Phytonomus globicollis Reiche & Saulcy 1857
- Phytonomus irregularis Bohemann 1842
- Curculio major autumn 1795
- Curculio sus autumn 1795
- Phytonomus fulvipes Stephens 1831
- Curculio dissimilis autumn 1795
- Phytonomus hampei Capiomont 1868
The species occurs in two subspecies, Limobius borealis borealis and Limobius borealis arvernus . The occurrence of Limobius borealis arvernus is limited to France.
The generic name Limobius is from Altgr. λειμών leimōn, meadow and βίος bios, derived from place of residence and says that the species of the genus live in open terrain. The genus Limobius is represented worldwide with only three species, all of which also occur in Europe.
Characteristics of the beetle
Due to the trunk-shaped extension of the head, the beetle is immediately recognizable as a weevil. Viewed from above, it looks like an acorn with a fruit cup that is too small, and therefore very similar to the species of the genus Hypera . A major difference, however, is that the second section of the antennae, the flagellum, is only six-membered (clearly recognizable in Fig. 2) and not seven-membered as in Hypera .
The body is covered with scales and bristle hair. The pale scales are elongated and cut by almost a third at the tip (Fig. 5). The bristle hairs are erect, black or white. They give the beetle a scruffy appearance.
The eyes are elongated and hardly curved. Its lower edge does not reach the lower edge of the trunk (Fig. 1 and 2).
The trunk is strong and about three times as long as it is wide. It cannot be placed on the chest in the resting position. It is slightly curved inwards and slightly widened towards the tip. In the front third, the back of the trunk is narrower than the underside of the trunk, which is why the antenna groove in the front part can be seen from above (Fig. 2), then it runs laterally towards the eye and ends in front of it (in Fig. 1 as a black, hairless groove) .
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| Fig. 1: top | Fig. 2: Front view | Fig. 3: Bottom |
The elytra are together significantly wider than the pronotum. The shoulders are broadly rounded. The abdomen ends broadly rounded. The wing covers are striped. All spaces between the rows of dots are equally flat. The uneven spaces are indistinctly white and dark latticed, but dark sections can also be found on the other spaces (in Fig. 1, they can be seen most easily).
The front hips are not brought closer to the rear edge of the front chest, but rather turned in about the middle between the front and rear edge of the front chest. They are very close together (Fig. 3). The rails have a small end pin on the inside (best visible in Fig. 4 on the front rails). The outer edges are unreinforced. The tarsi are all four-limbed, the third limb is broadened and deeply cut out (two-lobed). The claws are not grown together at the base (free).
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| Fig. 5: Scaling | |
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| Fig. 4: Larva | Fig. 6: Cocoon |
biology
The species lives oligophagous on various cranesbill plants of the genera Geranium and Erodium , it is also reported by other plants. It is most commonly found on Geranium sanguineum .
The species can only be found in dry and warm locations ( stenotopic , xerothermophilic ), for example on dry slopes, on dry meadows, on fields.
The beetle eats the leaves of the host plant. The larvae eat mainly the petals on the flowers (Fig. 4) , occasionally also sepals . You are at a transitional stage between ectophagy and endophagy . Although the development does not take place within the plant tissue as with real endophages, the pericarp offers a certain protection against predators.For pupation, the larvae create a pupal cocoon from their secretions, which is well camouflaged within the sepals (Fig. 6).
distribution
The species is native to Europe and the Caucasus, but mostly not common in Central Europe. The occurrence varies a lot. On the one hand, the beetle is classified as rare, on the other hand it is usually numerous at the sites where it is found.
literature
- Heinz joy , Karl Wilhelm Harde , Gustav Adolf Lohse (ed.): The beetles of Central Europe . tape 11 . Rhynchophora (end). Goecke & Evers, Krefeld 1983, ISBN 3-87263-031-8 .
- Adolf Horion: Beetle science for nature lovers. Vittorio Klostermann, Frankfurt am Main 1949.
- Klaus Koch : The Beetles of Central Europe . Ed .: Heinz Freude . tape 3 : ecology . Goecke & Evers, Krefeld 1992, ISBN 3-87263-042-3 , pp. 298 .
Individual evidence
- ↑ a b c F.E: Distribution, systematics and synonyms of Limobius borealis
- ↑ Red lists at BioNetworkX
- ↑ G. de Paykull: Monographia curculionum Sveciæ Upsala 1792 first description p. 57
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names (species)
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names (genus)
- ↑ Limobius at Fauna Europaea. Retrieved March 14, 2013
- ↑ Species of the genus Limobius at BioLib
- ↑ Mareike Güth: Landscape ecological aspects of the settlement of agriculturally used open land sites Diploma thesis Friedrich Schiller University Jena Institute for Ecology Jena 2000 as PDF ( Memento of the original from February 23, 2014 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ J. Skuhrocec: Which strategy of weevil larvae brings more benefits, endophagy or ectophagy ACTA ENTOMOLOGICA MUSEI NATIONALIS PRAGAE Vol 47, pp 287-306 4.xii.2007, ISSN 0374-1036 as PDF
