Blue swallow-root beetle
| Blue swallow-root beetle | ||||||||||||
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Blue swallow-root beetle |
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| Chrysochus asclepiadeus | ||||||||||||
| ( Pallas , 1773) |
   
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| Fig. 1: Different views | |
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| Fig. 2: Tarsus of the foreleg, links 1 - 3 numbered |
Fig. 3: Claw (hind leg) |
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| Fig. 4: Puncture on pronotum (P) and Elytres (E), same scale |
Fig. 5: Head, colors see text |
 
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| Fig. 6: Lower lip with lip probe, lower jaw with jaw probe (Reitter) |
Fig. 7: right upper jaw |
The blue swallow root beetle ( Chrysochus asclepiadeus ), also called swallow root leaf beetle , is a beetle from the leaf beetle family and the subfamily of the Eumolpinae . The genus Chrysochus is only represented in Europe with the species Chrysochus asclepiadeus . It occurs here in the subspecies Chrysochus asclepiadeus asclepiadeus . Chrysochus asclepiadeus asiaeminoris is probably not a real subspecies.
The species is listed in the Red List of Endangered Animals in Germany in category 2 (endangered).
Notes on the name
The beetle was first described by Pallas in 1773 under the scientific name Chrysomela Asclepiadea . Pallas' brief description of the beetle in Latin ends with the remark that he often found the species around Asclepiadem sibiracam ( Latin for the plant genus Asclepias sibirica , today Cynanchum thesioides ) towards the end of July . This explains the species name asclelpiadea , which he gave to the beetle. Pallas also mentions a find on Vincetoxicum , the swallowwort . The beetle feeds on this plant, not on Asclepias . This explains the German name Schwalbenwurzkäfer.
The beetle was described by Fabricius in 1792 under the name Chrysomela praetiosa . The species name published by Fabricius was adopted by many authors in the spelling pretiosus / a .
The generic name Chrysochus was adopted by Dejean in the new edition of the catalog of his beetles, which appeared in individual parts as early as 1836 and was published again in 1837 in one volume due to a fire, without a name explanation from Chevrolat , which Dejean also mentions in the foreword (page XIII). After Schenkling , the name of Altgr. χρυσός “chrysós” for “gold” and οχός “ochós” for “holding” and means “of gold-green color”. The blue swallow root beetle is not listed under Chrysochus at Dejean . It is usually not green, but, as the German name expresses, blue.
In 1798, Illiger lists in the appendix attempt a natural sequence of the orders and genera of the insects as the 92nd genus after Cryptocephalus and before Altica the genus Eumolpus . He adopts the generic name from Kugelann and states that the blue swallow root beetle belongs to this genus. In continuation of this name, the beetle is called Eumolpus asclepiadeus by some authors .
The genus Eumolpus is defined by Kugelann and Illiger only by specifying some species, not by a description. The description was made in 1801 by Weber in such a way that it does not include the blue swallow root beetle. In the sense of Kugelann, the scientific name Eumolpus asclepiadeus (Kugelann in Illiger) was used as a synonym for Chrysochus asclepiadeus , although this contradicted Weber's definition of Eumolpus . For this reason, the International Commission for Zoological Nomenclature in 2012 regulated the different uses of the generic name by resolution. The genus name was restricted to the species that correspond to the narrower definition of the genus Eumolpus given by Weber in 1801 , and the name Eumolpus asclepiadeus was thus invalid.
Characteristics of the beetle
With a length of eight to ten millimeters, the beetle is about as large as many species of the genus Chrysomela , but less oval than Chrysomela , but more cylindrical, but not truncated at the rear like other cylindrical species. The top is glossy deep blue to purple, sometimes greenish. The underside and legs are usually the same color as the top, but can be more greenish. The antennae and tarsi are almost black. A color variant with dark blue wing covers and a green head and pronotum has also been described. With the exception of the head, the beetle is hairless.
The head is drawn into the pronotum up to the rear edge of the eyes . He is almost imperceptibly hairy and scattered, roughly dotted . The vertex is more or less slightly indented lengthways (in Fig. 5 between the yellow arrowheads). A furrow runs above and in front of the slightly kidney-shaped eyes (green and blue in Fig. 5). The eleven-link antennae are half as long as the beetle, shaped like a pearl necklace and slightly thickened towards the end. The end link has a short, stepped point that can simulate a twelfth link. The first parts of the antennae can be brownish. The antennae are widely separated from one another and are deflected over the roots of the upper jaw. They cannot be placed in sensor pits. The upper lip (tinted red-brown in Fig. 5) is cut out at the front and forms a clear angle with the head shield behind . The upper jaws are strong, angled inward to different degrees in the front right and left and they end with two pointed ends (Fig. 7 right upper jaw from above). The two tips interlock when the upper jaw is closed. The shape of the lower lip with the lip buttons or a lower jaw with the jaw button can be seen in Figure 6 on the left and right. The egg-shaped short end link of the four-part jaw probe, which is much thicker than the penultimate part, is important for the system.
The pronotum is almost half as wide as it is long, longer in the female than in the male. It is arched high. It is edged all around, but the edge is not visible from above on the sides. The dots are fine and extensive (left in Fig. 4).
The scutellum is broadly triangular and smooth.
The elytra are only slightly wider than the pronotum. They completely cover the abdomen and are a good one and a half times as long as together wide. They are depressed behind the slightly protruding shoulders. The puncture is only slightly thicker and stronger than on the pronotum, the points are disordered, at most in the rear area in irregular rows (in Fig. 4 right). The wing covers end together rounded.
The front hips are spherical and pivoted away from each other. Not only the third, but also the second tarsal link is bilobed. It encompasses the base of the third link. As a result, the second, together with the third tarsal link and the claw link, act as a unit that is clearly separated from the first tarsal link (Fig. 2). The underside of the tarsi are densely covered with white bristles. The claws are very small and serrated at the base, the inner half a third shorter than the outer (Fig. 3). The rails are extended by a wide tooth on the outside in front of the end.
The male is more punctured than the female, the pronotum is slightly wider and the first tarsi of the front and middle pair of legs are wider.
biology
The biology of the species is relatively well known for a beetle of no economic importance. The beetle was examined to see whether it could be used for biological control of weeds that were introduced into North America. The beetle lives on the swallowwort ( Vincetoxicum hirundinaria , formerly Vincetoxicum officinale ). The larvae feed on the roots, the adults feed on the leaves. The plant and animal are so well adapted to each other that the plant is not significantly damaged. The species is considered to be monophagous on Vincetoxicum hirundinaria in Central Europe , but populations have been found on Vincetoxicum nigrum in France and the beetle has been found on Vincetoxicum rossicum in Ukraine . There may be different subspecies in each case. In North America, Vincetoxicum rossicum and Vincetoxicum nigrum are classified as weeds. Experiments have shown that larvae of the blue swallow- root beetle can also develop to sexual maturity on some other plants than Vincetoxicum hirundinaria if the larvae are placed on these plants. In doing so, they sometimes cause considerable damage to these plants, even to the point of death. However, if the beetles have a free choice when it comes to laying their eggs, they choose Vincetoxicum hirundinaria . They prefer dry and sunny locations.
In Europe, the host plant is much more widespread than the beetle. There is evidence that not only the occurrence of swallowwort, but also the presence of other plants plays a role in the choice for egg-laying. The flight muscles of the species are poorly developed, and the beetle has only limited flight capabilities. In tests, a spread of less than 15 m was measured in 25 days. The beetles usually stay in groups with an infected plant until it has defoliated. The adults consume less leaf mass in sunlight than in shade. This is because they crawl into the ground in full sunlight.
The eggs are laid in the ground. The development time varies greatly. The species overwinters as a larva, it takes one to three years to develop into an imago.
When disturbed, the adults secrete a colorless, foul-smelling, bitter but non-toxic liquid from glands on the breast shield and on the wing covers, which presumably deter predators. As part of the above-mentioned investigations to control swallowweed, investigations were also carried out on this. The analysis of the secretion revealed the main components tryptophan , phenylalanine , leucine and diacetylputrescine . In contrast to the North American species Chrysochus auratus and Chrysochus cobaltinus , which also secrete, but much more sparingly, no cardenolides were found . The cardinolids come from the herbivore. Corresponding plants are avoided by the blue swallow root beetle and the cardenolides have a toxic effect when administered by blocking the sodium-potassium pump , while in the North American species they are transported into the glands on the breast shield and wing covers, and then in the secretion as a poison to protect against predators can be used. When examining the DNA for the α-subunit of the sodium-potassium pump, to which the cardenolides presumably dock and thus block the pump, it was found that the genetic code for the amino acid asparagine was in position 122 in the blue swallow- root beetle in contrast, a codon for histidine in the two North American species . This point mutation opens up the plants that contain cardenolides as a food source for the American species and provides them with a poison against predators, while such plants are poisonous for the blue swallow root beetle.
distribution
The species is distributed from Spain to Syria , Armenia and Siberia , and according to other sources to Mongolia and northern China . In Europe it is absent in Portugal and becomes rarer towards the north. There are no reports from the British Isles , Denmark , Scandinavia and Estonia . The beetle does not occur in Ukraine , Belarus , Moldova or the European part of Turkey either. The distribution area in the individual countries is very fragmented.
literature
- Heinz joy, Karl Wilhelm Harde, Gustav Adolf Lohse (ed.): The beetles of Central Europe . tape 9 . Cerambycidae Chrysomelidae . Spektrum Akademischer Verlag, Munich 1999, ISBN 3-8274-0683-8 (first edition: Goecke & Evers, Krefeld 1966). P. 148
- Klaus Koch : The Beetles of Central Europe . Ed .: Heinz Freude . tape 3 : ecology . Goecke & Evers, Krefeld 1992, ISBN 3-87263-042-3 . P. 73
- Edmund Reitter : Fauna Germanica, the beetles of the German Empire, Volume IV, KGLutz 'Verlag, Stuttgart 1912, p. 107
- Gustav Jäger (Ed.): CG Calwer’s Käferbuch . K. Thienemanns, Stuttgart 1876, 3rd edition p. 578 as Chrysochus pretiosus
Individual evidence
- ^ Edmund Reitter : Fauna Germanica, the beetles of the German Empire, Volume IV, KGLutz 'Verlag, Stuttgart 1912, plate 144 Fig. 6c, 6b
- ↑ Chrysochus in Fauna Europaea. Retrieved January 12, 2016
- ↑ a b Chrysochus asclepiadeus in Fauna Europaea. Retrieved January 12, 2016
- ↑ Ali Nafiz Ekz et al: "Occurence of Chrysochus asclepiadeus in Turkey: Two distinct subspecies or the same taxon with slightly different populations" in Zoology in the Middle East Vol. 61, Issue 2, 2015 doi : 10.1080 / 09397140.2015.1020608
- ↑ Red List of Endangered Animals in Germany (Binot et alt. 1998) ( Memento of the original from March 1, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ PS Pallas journey through different provinces of the Russian Empire - the second part, second book in the 1771th year St. Petersburg 1773 p. 359: 725
- ^ Joh. Chr. Fabricius: Entomologiae systematicae, emmendatae et auctae Volume 1, Hafnia (Copenhagen) 1792 p. 324, 85. Kind of Chrysomela preview in the Google book search
- ^ Dejean: Catalog de la Collection de Coléoptères de M. Le Baron Dejean Paris 1837 Preview in the Google book search
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names (genus)
- ↑ JGKugelann, J.Ch.Hellwig, JkW Illiger: Directory of Beetles in Prussia Hall 1798 with an attempt at a natural sequence of the orders and genera of the insects preview in the Google book search
- ^ Friedrich Weber : Observationes entomologicae Kiel 1801 Preview in the Google book search
- ↑ Case 3519 of the ICZN
- ^ A. Fleischer: “A new color aberration of Chrysochus asclepiadeus Pall.” In Wiener Entomologische Zeitung XXIX. Year, Vienna 1910 p. 200
- ↑ WF Erichson et al .: Natural history of the insects of Germany 6th volume, Berlin 1893 p. 296
- ^ Ludwig Redtenbacher: Fauna Austriaca - Die Käfer 3rd edition, 2nd volume, Vienna 1874 p. 453
- ↑ M. Olivier: Entomologie ou Histoire Naturelle des Insectes Coleoptères Tome VI Paris 1808 p. 904 as Eumolpus preciosus
- ^ Th. Lacordaire, F. Chapuis: Histoire Naturelle des Insectes - Genera des Coléoptères 10th volume Paris 1874 p. 341 genus Chrysochus
- ^ A. Gassmann et al .: "Evaluating the Potential for Biological Control of Swallow-Worts ( Vincetoxicum nigrum and V. rossicum ) in Eastern North America" Session 1 Pre-Release Testing of Weed Biological Control Agents, XIII International Symposium on Biological Control of Weeds 2011 as PDF
- ^ A. Gassmann et al .: "Biological control of swallow-worts Vincetoxicum nigrum and V. rossicum " - Annual Report 2011 Cabi 2012 as PDF
- ^ R. Sforza et al .: "Ecological Data-Key to Building a Successful Biocontrol Programs: A Case Study Using Chrysochus asclepiadeus (Coleoptera: Chrysomelidae) Against Vincetoxicum spp. (Apocynaceae) “Session 7 Ecological and Evolutionary Processes, XIII International Symposium on Biological Control of Weeds 2011 as PDF
- ↑ Robert S. Bourchier et al .: " Vincetoxicum nigrum (L.) Moench V. rossicum (Kleopov) Barbar., Swallow-Worts, Dog-Strangling Vine (Apocynaceae)" in Peter G. Mason, David R. Gillespie (ed .): Biological Control Programs in Canada 2001-2002 Chapter 60, p. 404
- ↑ Pierre Jolivet, Krishna K. Verma: Eumolpinae, a widely distributed and much diversified subfamily of leaf beetles (Coleoptera: Chrysomelidae) in Terrestrial arthropod Reviews 1 (2008) pp. 3-37 as PDF
- ↑ Estelle Labeyrie, Susanne Dobler : "Molecular Adaptation of Chrysochus Leaf Beetles to Toxic Compounds in Their Food Plants" Oxford Journals - Molecular Biology and Evolution Vol. 21, Issue 2 pp. 218-221 as PDF
- ↑ Susanne Dobler, Désiré Daloze, Jacques M. Pasteels: "Sequestration of plant compounds in a leaf beetle's defensive secretion: cardenolides in Chrysochus " Chemoecologie 8: 111-118 (1989) as PDF
- ↑ Blagoy Gruev: The leaf beetles (Coleoptera: Chrysomelidae) of the Pirin mountains (Bulgaria) Historia naturalis bulgarica 17: 51–79, 2006 p. 59 ( Memento of the original from January 22, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and not yet tested. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Distribution map of Fauna Europaea ( memento of the original from January 22, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Distribution map in Central Europe ( Memento of the original from January 23, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
