Southern cereal tree beetle
| Southern cereal tree beetle | ||||||||||||
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Southern cereal tree beetle, female |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Anisoplia austriaca | ||||||||||||
| ( Autumn , 1783) |
The Southern corn leaf beetle ( Anisoplia austriaca ) is a beetle from the family of Rutelidae belonging to the superfamily of Scarabaeoidea belongs. The species is represented in Europe with three subspecies, of which only the nominate form Anisoplia austriaca austriaca occurs in Central Europe . The subspecies Anisoplia austriaca hordearea is restricted to the Dodecanese , Anisoplia austriaca major occurs only in southern Russia .
The generic name Anisoplia means that the two claws that sit on the last tarsal link are of unequal length ( ancient Greek ἄνισος ánisos “unequal” and ὁπλή hoplē “claw”). The species name austriaca ( lat. ) Means "Austrian" and refers to the distribution area.
Characteristics of the beetle
The 13 to 16 millimeter large body is broadly oval and black with green shades, the wing covers yellow or reddish brown. In the female, the label is embedded in a large, dark, mostly rectangular patch.
The head is directed forward. The wrinkled head shield is elongated like a snout, pinched off in front of the tip and bent up. In supervision he covers the mouthparts . The antennae are nine-part, the fan three-part.
The dense, strong and unevenly punctured pronotum is narrower than the elytra, widest in front of the middle and towards the bordered base with a weakly indicated longitudinal impression. The front of the pronotum is lined with membranes, the front corners are almost rectangular.
The brown-yellow to red-brown elytra have a row of short bristles in the shoulder area, but bristle-shaped hairs are missing in the rear half of the outer edge of the elytra, as can be found in the similar Chaetopteroplia segetum . The point stripes are only indicated. The outer sides are completely lined with skin. The marginal calluses of the females are strongly developed.
The front hips are keeled transversely near the front edge. The front rails have two teeth on the outside and a movable mandrel on the inside. In the male, this is opposite the rear external tooth, in the female in front of it. The middle and rear rails have two spikes that are brought closer together at the end. The tarsi are five-part. The claws are of different lengths, the inner claw shorter than the outer. In the males, the larger claw of the forefoot is long and thin and slightly curved, and on the underside just before the end there is an obtuse-angled tooth.
Egg, larva, pupa
The eggs are white and almost spherical with a diameter of two millimeters. The up to 35-millimeter larvae are white grubs , white with brown head and legs. The pupa is yellow-brown and becomes fifteen to seventeen millimeters long.
development
The development of the thermophilic species takes two years and takes place in the soil. The adults fly in June and July and can be found on the ears of grass and grain. In July, the females lay around 50 eggs in two to three servings eight to twenty centimeters deep into the ground. Depending on the soil temperature, the larvae hatch after two to four weeks. They are relatively moisture-loving. In dry periods they withdraw into deeper soil layers. In the first year they feed on soil humus and small roots of various plants, preferably on the edges of grain fields. The larvae overwinter in the first stage and a year later in the second stage at a depth of 30 to 80 centimeters. They become active again at the end of April when the upper soil layers warm to 8 ° C. The larvae of the second year appear about 10-20 days before those of the first.
In the second year of their development, the larvae prefer the roots of cereals and sugar beets . Pupation takes place in May at a depth of eight to fifteen centimeters. The beetle hatches ten to twenty days later. It appears at a minimum temperature of at least 17 ° C, the females need temperatures of at least 20 ° C for sexual maturation. The beetles are diurnal and mainly active on warm days around noon. At night they crawl into the ground, where they remain on cool and cloudy days.
Natural enemies
Many species of birds are natural enemies of larvae and beetles; the larvae are also parasitized by numerous hymenoptera such as Tiphia femorata , Tiphia morio or Scolia sexmaculata . As early as 1879, Elie Metchnikoff experimented with the soil-dwelling fungus Metarhizium anisopliae in order to use it to combat the larvae of Anisoplia austriaca . The fungus penetrates the insect through pores and multiplies inside, causing the insect to die.
Effects on Agriculture
The original steppe dwellers are particularly harmful to grain in black earth soils in the Ukraine and southern Russia as well as in the western and eastern regions of Kazakhstan and Azerbaijan . However, outbreaks of damage were also reported in Austria in extremely dry years (local damage occurred in 2003 in Ebenfurth / Lower Austria due to eating the grains at the end of the dough maturity). The populations grow in hot, dry years and decline significantly in cool, humid years.
The damage occurs in multiple ways. A single beetle only eats about eight grams of grain, but drops many grains on the ground, destroying nine to ten ears of wheat in the process. The larvae feed on the roots thins the density of the seedlings. With a density of more than 10 grubs with 250 seeds per square meter, a loss of up to 50% is expected. However, densities of 60 to 100 beetles per square meter are observed at field edges. The threshold for the use of insecticides is given as three beetles per square meter. There are also various ways of limiting damage through the timing of sowing, harvesting and plowing.
distribution
The Pontic species (the adjective Pontic is derived from Pontos Melas for Black Sea) is mainly found in south-east Europe, to the west the range extends to Hungary, Austria and Slovakia, to the east it extends to Armenia and Iran.
literature
- Heinz joy , Karl Wilhelm Harde , Gustav Adolf Lohse (ed.): The beetles of Central Europe . tape 8 . Teredilia Heteromera Lamellicornia . Elsevier, Spektrum, Akademischer Verlag, Munich 1969, ISBN 3-8274-0682-X .
Individual evidence
- ↑ Proof of use of the German name (PDF; 437 kB)
- ↑ a b Anisoplia austriaca at Fauna Europaea. Retrieved February 10, 2011
- ^ Anisoplia austriaca austriaca at Fauna Europaea. Retrieved February 10, 2011
- ↑ Anisoplia austriaca hordearia at Fauna Europaea. Retrieved February 10, 2011
- ^ Anisoplia austriaca major in Fauna Europaea. Retrieved February 10, 2011
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names
- ↑ a b c d e Information Agroatlas
- ↑ Lyudmila Trepashko Chance of Entomocomplexes Structur in Agrocoenosis of Grain Crops in Belarus Zemdirbyste-Agriculture vol. 95, No.3 (2008) pp. 209-214 ISSN 1392-3196 as PDF
- ↑ Brief information on Metarhizium anisoplae
- ↑ Distribution area in Asia
- ↑ Harmful outbreaks in Austria (PDF; 53 kB)
- ↑ Polish koleopterologische site
