Rapeseed beetle

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Rapeseed beetle
Green rapeseed beetle (Brassicogethes aeneus)

Green rapeseed beetle ( Brassicogethes aeneus )

Systematics
Order : Beetle (Coleoptera)
Superfamily : Cucujoidea
Family : Gloss beetle (Nitidulidae)
Subfamily : Meligethinae
Genre : Brassicogethes
Type : Rapeseed beetle
Scientific name
Brassicogethes aeneus
( Fabricius , 1775)

The rapeseed beetle ( Brassicogethes aeneus ) is a beetle from the family of the gloss beetle (Nitidulidae).

features

Green rapeseed beetle are only about two millimeters long. The chitin armor has a metallic sheen, the color varies in different individuals, it can be green, blue, purple or even black. The body has an oval shape. The elytra are covered with tiny hairs. Both the legs and the antennae are colored brown. The short antennae thicken into a club at the end.

Occurrence

The beetles are widespread in Europe , North Africa , Asia and North America . They stay mainly in open or bushy terrain.

Way of life

Green rapeseed beetle on flower

The animals sit on flowers during the day. They don't feed exclusively on rapeseed , but generally on cruciferous vegetables. Pollen beetles eat the pistils and ovaries of the flowers in addition to the pollen. In the case of mass occurrences, the beetles can cause considerable damage to agriculture. The larvae also live in flowers, but only feed on pollen and therefore pose no threat to the economy. After several moults, the larva pupates in the ground. In the same year, the finished beetle hatches around the time the rape is in bloom at an air temperature of 9 ° C.

In the summer of 2006 there was a massive occurrence of the rapeseed beetle in eastern Schleswig-Holstein in Germany.

The beetles are also able to make sounds.

Combat

The control of the rapeseed beetle has been carried out almost exclusively with pyrethroids in the last 20 years . The pollen beetles are loaded with the insecticide as soon as they move in the sprayed crop or are directly caught by the insecticide. The effect sets in relatively quickly: the beetles are disoriented and move irregularly, they “stagger”. They eventually fall from the rapeseed plants and can then no longer be found on the plants. Since pyrethroids do not penetrate the plant, they can be washed off relatively quickly by rainfall or be broken down in strong sunlight. Pyrethroids can be used well at temperatures between 5 and 15 ° C.

These insecticides are divided into class 1 (e.g. bifenthrin ) and class 2 (e.g. deltamethrin ) according to their chemical structure . In the last 10 years the effectiveness of these pyrethroids against the pollen beetle has decreased across Europe. There are many reasons for this, e.g. B. the expansion of the cultivation area of ​​rapeseed. Resistance occurs primarily in class 2 pyrethroids and is based on enzymatic breakdown of the insecticide in the insect's body.

In addition to the use of insecticides, a large number of other control options are being discussed, but these have so far found little use in agricultural practice. The use of entomopathogenic fungi , trapping plants or the promotion of beneficial insects , e.g. B. Parasitoids .

As of May 2019, plant protection products with the active ingredients acetamiprid , bifenthrin, chlorpyrifos , chlorpyrifos-methyl , etofenprox , indoxacarb , kaolin , pymetrozine , spinosad and thiacloprid are permitted in Switzerland to control the pied pollen beetle ; Organic farming and IP-Suisse limit themselves to the use of kaolin.

Parasitoids

The parasitoids of the pollen beetle larvae are endoparasitoids and belong to the order of the Hymenoptera . For Europe so far nine species were identified as parasitoids of rape pollen beetle. The parasitoids that occur most frequently on the pollen beetle in Germany are Phradis interstitialis (Thomson), Phradis morionellus (Holmgren) and Tersilochus heterocerus Thomson. These three species form only one generation per year ( univoltin ).

The adult parasitoids look for the larvae of the rapeseed beetle (host larvae) on the flowers and pierce them with the ovipositor . They lay a single egg in the larvae of the pollen beetle. Initially, the host larva is not damaged, but continues to develop. After the third larval stage, the host larvae drop from the oilseed rape plant to the ground, where they burrow to pupate. At this moment (or shortly before) the larva of the parasitoid hatches inside the host larva. The host larva then dies in its pupation cocoon in the ground. In the following year, the adult parasitoid hatches from the earth's cocoon. The cycle begins again.

Parasitization rates of more than 50% are possible. The degree of parasitization, however, depends on a number of factors ( climate , rapeseed variety , arable factors). A host larva can be parasitized by two different types of parasitoids.

Taxonomy

The following synonyms are used in the literature :

  • Meligethes bonvouloiri C. Brisout de Barneville , 1872
  • Meligethes brassicae Reitter , 1875
  • Nitidula coeruleus Marsham , 1802
  • Meligethes moerens LeConte , 1857
  • Meligethes mutatus Harold , 1868
  • Meligethes rotundangulus Ganglbauer , 1899
  • Meligethes rufimanus LeConte , 1857

swell

Individual evidence

  1. ↑ Pests: Green rapeseed beetle. In: psm.admin.ch . May 7, 2019, accessed May 25, 2019 .
  2. ↑ Kaolin in the extensor rape. In: ipsuisse.ch. Retrieved May 25, 2019 .
  3. ↑ Brassicogethes aeneus in Fauna Europaea. Retrieved February 24, 2011 .

literature

  • Jiři Zahradnik, Irmgard Jung, Dieter Jung et al .: Beetles of Central and Northwestern Europe. Parey, Berlin 1985, ISBN 3-490-27118-1
  • Edmund Reitter : Fauna Germanica: The beetles of the German Empire. Volume 3 p. 17, K. G. Lutz, Stuttgart 1911
  • Edmund Reitter: Fauna Germanica: The beetles of the German Empire. 5 volumes, Stuttgart K. G. Lutz 1908-1916, digital library volume 134, Directmedia Publishing GmbH, Berlin 2006, ISBN 3-898-53534-7
  • David V. Alford: Biocontrol of Oilseed Rape Pests. Blackwell Publishing, Oxford 2003 ISBN 0-632-05427-1
  • Olaf Christen, Wolfgang Friedt : Winter rapeseed - The manual for professionals. DLG Verlag, Frankfurt 2007. ISBN 978-3-7690-0680-3
  • Volker H. Paul: Oilseed rape - diseases, pests, harmful plants. Th.Mann Verlag, Gelsenkirchen-Buer 2003. ISBN 3-7862-0148-X

Web links

Commons : Rapsglanzkäfer ( Brassicogethes aeneus )  - Album with pictures, videos and audio files