Blue leafhopper
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Blue leaf hoppers ( Metcalfa pruinosa ) |
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| Metcalfa pruinosa | ||||||||||||
| ( Say , 1830) |
The citrus flatid planthopper ( Metcalfa pruinosa ) is a cicada within the family of butterfly cicadas (Flatidae). In Europe, the species originating from North America occurs as a neozoon .
features
The adult blue leafhopper reaches a body length between 5 and 8 mm and is 2 to 3 mm wide. It has wide triangular fore wings that it holds vertically close to the body, giving it a wedge-shaped, laterally compressed appearance. The forewings have well-developed, transversely veined costal cells . The posterior tibiae usually have two lateral spines in addition to those at the apex.
The color varies from whitish to gray to dark gray, depending on how much the cicada is covered with bluish white wax particles. In the basal regions of the forewings there are characteristic pairs of dark spots.
The nymphs grow up to 4 mm long and are less than twice as long as they are wide. They have distinct wing stubs and conspicuous clusters of white wax threads at the rear end of the abdomen. The color varies between whitish and light green.
distribution
Because of its origin in North America - known there as Citrus flatid planthopper - the blue leaf cicada is also known as the American cicada . It prefers mixed forests , open scrubland and similar biotopes. Their distribution area extends along the North American east coast from Ontario and Québec to Florida , to the west to the Great Plains . In the southwest it occurs in Texas , New Mexico , Arizona , California and Mexico . The subspecies Metcalfa pruinosa cubana ( Metcalf & Bruner ) is said to be widespread in Cuba .
In the late 1970s, the blue leafhopper arrived in southern Europe via plant imports. It was first found in 1979 in Veneto , Italy . Since then it has been able to firmly establish itself in central and northern Italy as well as in southern France. In addition to the neighboring countries of Italy, Slovenia , Croatia and Switzerland, it spread to Spain , Hungary , Serbia , Montenegro , Bulgaria , Greece and Turkey . It was first found in the Czech Republic in 2001, but there, as in Great Britain , is considered to be eradicated again. In Austria, after a single find in Graz in 1996, a mass occurrence in the area around Vienna was established in July 2003 . The species can now be found frequently in both Graz and Vienna.
Way of life
The blue leafhopper develops one generation a year. After overwintering in the egg stage, the larvae hatch between March and June depending on the region, depending on the outside temperature. Their excellent jumping ability distinguishes them from the larvae of the woolen or scale insects , which also produce wax wool and which are often found on the same plants. Adult cicadas hatch after five larval stages. These mate and begin to lay eggs. The female lays the eggs between late summer and late autumn with her short ovipositor in corked parts of bark or lenticels of various trees or bushes.
The blue leafhopper feeds extremely polyphagous . In Austria alone it was found on 290 different plants. Their wide food spectrum includes both cultivated plants such as various citrus plants, types of fruit, grapevines, sunflowers, maize or soy as well as numerous herbaceous and woody wild plants.
Harmful effect and benefit
By sucking plant juices, the blue leaf hoppers rarely cause economic damage to healthy host plants. A transmission of viruses or phytoplasms has not yet been determined, but a connection with certain diseases occurring in North America in grapevines ( Grapevine yellows disease ) has been suspected. In the event of severe infestation, however, plant growth and fruit development can be impaired. The honeydew excreted by the animals , on which sooty dew settles and which contaminates the host plants , causes greater problems . The moulting residues left on the plants and the wax wool are a visual impairment, especially with ornamental plants.
The blue leaf hoppers are mainly chemically combated in the fruit and wine growing of southern Europe. However, since the animals produce large amounts of honeydew, which is ingested by honey bees and other insects, this can damage the bee colonies and impair the quality of the honey. Metcalfa honey from the honeydew of the blue leafhopper has meanwhile achieved great economic importance in southern Europe, especially in Italy, Slovenia and France.
literature
- David V. Alford: Pest of Fruit Crops. A Color Handbook. Elsevier, 2007, ISBN 978-0-12-373676-5 , pp. 45-46 ( Google books ).
- FW Mead: Citrus Flatid Planthopper, Metcalfa pruinosa (Say) (Insecta: Hemiptera: Flatidae). EENY-329 (orig. Publ. As DPI Entomology Circular 85), Featured Creatures series, Entomology and Nematology Dept., Florida Cooperative Extension Service, Inst. Of Food and Agricultural Sciences, Univ. of Florida, June 2004 ( PDF version ).
- Rudolf Moosbeckhofer u. a .: Studies on the occurrence of the blue leafhopper Metcalfa pruinosa (Say 1830; Hemiptera, Flatidae), a new honeydew producer in Austria, and the possible effects on beekeeping. Final report. Austrian Agency for Health and Food Safety, 2008 ( PDF ; 2.3 MB).
Individual evidence
- ↑ Pavel Lauterer: Citrus Flatid Planthopper - Metcalfa pruinosa (Hemiptera: Flatidae), a New Pest of Ornamental Horticulture in the Czech Republic. In: Plant Protection Science. Vol. 38, no. 4, 2002, pp. 145–148 ( PDF ( Memento of the original dated September 23, 2004 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , 246 kB).
- ↑ Gudrun Beckh, Gregor Camps: New specifications for traditional honeys. In: Deutsche Lebensmittel-Rundschau. February 2009, p. 109 ( PDF ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice .; 114 kB).
Web links
- The blue leafhopper (Metcalfa pruinosa). Austrian Agency for Health and Food Safety, accessed on August 23, 2010 .
- Entry on Metcalfa pruinosa in Fauna Europaea