Timothy weevil
| Timothy weevil | ||||||||||||
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Timothy weevil ( Sphenophorus striatopunctatus ) on field path |
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| Scientific name | ||||||||||||
| Sphenophorus striatopunctatus | ||||||||||||
| ( Goeze , 1777) |
The timothy weevil ( Sphenophorus striatopunctatus ) is a beetle from the family Dryophthoridae , which belongs to the weevil-like family. Traditionally, the genus belongs to the subfamily Rhynchophorinae of the family Curculionidae . Synonyms are Rhynchophorus abbreviatus Herbst 1795, Curculio fimbriatus Gmelin 1790, Sphenophorus helveticus Stierlin 1882 and Curculio mutilatus Laichartaing 1781. The genus Sphenophorus is represented in Europe with five species .
The generic name Sphenophorus from ancient Greek σφήν 'sphēn, sphenós' 'wedge' and φορός 'phorós' 'carrying' probably refers to the shape of the trunk. The species name striatopunctatus from Latin 'striātus' 'striped' and 'punctātus' 'dotted' refers to the elytra on which stripes and points alternate. The timothy weevil owes its name to its development in timothy grass .
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| Fig. 2: Sensor from behind | |
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| Fig. 1: Eye (right edge of the pronotum) |
Fig. 3: Detail of the wing cover |
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Fig. 4: right front leg (rail and tarse) from behind |
Characteristics of the beetle
The black, long oval beetle reaches a length of 6.5 to 9 millimeters (without a trunk). It is the smallest of the three Central European species of the genus. It is arched flat and appears bald.
The trunk, which is moderately curved downwards, is about as long as the pronotum, almost smooth and stretched forward. At the point of deflection of the antennae it is thickened, before that it is round and slender. The antenna base is wider in the females than in the males. The oval pit in which the sensor is pivoted is close to the sensor base and does not open into a sensor groove (Fig. 1). It is delimited with sharp edges, but not closed off at the back by a blunt tooth. The antennae (Fig. 2) are kneeled, the shaft is slightly longer than the whip without a club. The second part of the antennae whip is not markedly longer than it is wide, the following parts are wider than it is long. The six-membered flagellum is more compact than in the other two Central European species. The noticeably flattened antenna lobe consists of three sections. The last two are small and densely hairy, the first glossy and, in contrast to similar species, with rounded sides. The kidney-shaped eyes are very shallow and are lower on the sides of the head than the trunk (Fig. 1).
The pronotum is longer than it is wide and tapers more towards the front than towards the back. The widest point is about in the middle, it is narrower than the elytra together. At the front edge, the pronotum is pinched off in a line, except in the middle, its base slightly convex . The pronotum is strongly punctured , the puncture becomes less dense towards the middle and has disappeared in a narrow longitudinal strip in the middle.
The elytra are elongated, almost ovoid. At the end they are individually rounded and leave the pygidium uncovered. This is dense and strongly punctured. A shoulder bulge is formed. The elytra are divided into alternating wide intervals by finely torn point strips. Two to three irregular rows of dots run on these. The 2nd, 4th, 6th, ... interval is usually narrower and more densely dotted than the odd intervals. This creates an unusual pattern. At each point a small, yellowish hair flake emerges, which, however, can only be clearly seen when enlarged and with favorable incidence of light (Fig. 3).
The abdomen shows five segments on the underside, which are delimited by straight seams. The fifth segment is wider than the third and fourth together. The front hips are separated. The rails are finely keeled lengthways. The keels delimiting the rear are ciliate. The splints end in a strong, inwardly curved mandrel that attaches to the front and inside (Fig. 4). The tarsi are apparently four-limbed, the claw limb is remarkably long.
biology
The larvae develop in the roots of rushes and sedge. Common timothy and common rush are preferred . The adults are long-lived and overwinter hidden in moss. They need warm and dry places near the water, such as sandy spots in sunny floodplains or river dams. Accordingly, artificial biotopes such as golf courses also offer a favorable living space. On sports facilities and golf courses in Italy, the larvae in the roots of a mixed lawn with German ryegrass and meadow bluegrass became harmful. In experiments with 120 varieties of meadow bluegrass, only 20 varieties were damaged by the larvae. The varieties “Princeton”, “Optigree” and “Midnight” were most endangered, the variety “Conni” was least damaged.
The species produces one generation per year. She hibernates as an imago . The beetle appears in spring and is most commonly found in May. He performs a ripening process . The eggs are deposited individually in the leaf sheath on the basal part of the plants. In Italy, the larvae hatch in May. They live in the lowest layer of the lawn and feed on the root necks. In July, depending on the moisture, they penetrate up to ten centimeters into the ground and feed on the grass roots. They continue this feeding in August. Pupation takes place in the root neck, the adults appear at the end of August and soon retreat to their winter quarters. It takes about 100 days from egg-laying to hatching of the imago, with seven larval stages occurring. The adults are 10 to 11 months old. The damage to the lawn (yellowing to death) can be observed in June and July.
distribution
The species is common in southern and central Europe. The beetle is rare in Central Europe and is absent in the lowlands. The species is absent in Portugal . The northern border of the distribution area runs through France , the Benelux countries , Germany , Poland , Belarus and the Ukraine . However, the distribution area is patchy. There are no reports of finds from the Czech Republic and Slovakia , Slovenia , Croatia , Bosnia-Herzegovina , Albania , Macedonia , Greece and Moldova .
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 .
- Gustav Jäger (Ed.): CG Calwer’s Käferbuch . K. Thienemanns, Stuttgart 1876, 3rd edition
- Edmund Reitter : Fauna Germanica, the beetles of the German Empire V. Volume, KGLutz 'Verlag, Stuttgart 1916
Individual evidence
- ↑ a b Sphenophorus at Fauna Europaea. Retrieved March 4, 2012
- ↑ Heinz Freude , Karl Wilhelm Harde , Gustav Adolf Lohse (ed.): Die Käfer Mitteleuropas . tape 11 . Rhynchophora (end). Goecke & Evers, Krefeld 1983, ISBN 3-87263-031-8 .
- ↑ a b Sphenophorus striatopunctatus in Fauna Europaea. Retrieved March 4, 2012
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names.
- ↑ Klaus Koch : The beetles of Central Europe . Ed .: Heinz Freude . tape 3 : ecology . Goecke & Evers, Krefeld 1992, ISBN 3-87263-042-3 .
- ↑ a b E. Chapin, JF Germain: " Sphenophorus striatopunctatus : Un ravageur nouveau pour les gazons de graminées." Draft ( Memento of the original of September 7, 2012 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. (PDF file; 306 kB)
- ↑ ALMA A., 2002: Sphenophorus striatopunctatus Informatore fitopatologico, 69 (1), pp. 8th.
- ↑ SZALAY-MARZSÓ L. (1958): "Morphology and biology of the Sphenophorus striatopunctatus Goeze ( timothy weevil )." Acta Zool. Ac. Sci. Hung. IV. 1-2: pp. 211-252.
