Big rapeseed flea
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Great rapeseed flea ( Psylliodes chrysocephalus ) |
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| Psylliodes chrysocephalus | ||||||||||||
| ( Linnaeus , 1758) |
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The great rapeseed flea ( Psylliodes chrysocephalus ) is a beetle from the family of leaf beetles (Chrysomelidae).
features
The beetles are three to four millimeters long. Their body is elongated oval and black-blue, or more rarely brown, colored with a metallic sheen.
The larvae are six to seven millimeters long and colored dirty white, their heads are dark brown. You have three pairs of legs.
Way of life
The larvae feed on cruciferous plants (Brassicaceae), whereby in addition to field mustard ( Sinapis arvensis ) and field radish ( Raphanus raphanistrum ) all cultivars of the cruciferous family, such as. B. rape ( Brassica napus ), all types of cabbage ( Brassica oleracea ) and stubble ( Brassica rapa ) are eaten. The great rapeseed flea only trains one generation per year. The adult beetles hatch from the soil of the rapeseed fields in June / July and initially feed on old rapeseed stocks or weeds. In midsummer the beetles go through a summer dormancy, where they retreat to cool and shady habitats (field, edge of forest). From the beginning of September immigration to the freshly emerging rapeseed stocks takes place. The females first go through a process of ripening before they begin to lay eggs in the ground near the rape plant. Depending on the weather, egg laying can continue into spring.
Harmful effect and control
The mining tunnels in leaf stalks, boreholes with excrement remains on the leaf stalks and in the heart of the plants in late autumn or early spring indicate infestation by larvae of the great rapeseed flea. The beetles colonize the host plants in September and, when temperatures drop, lay their eggs in the ground next to the plants from around the beginning of October . The larvae penetrate from the petioles to the heart and the later stem, weaken the plants and can also cause deformities. The larvae are able to change leaves as soon as the pith in the petiole has been eaten away.
Infested plants have a reduced winter hardiness, since water and pathogens can penetrate through the injuries. Namely, canola seed partially incrusted marketed, but the effect of the agent is sufficient only until the third true leaf . The influx should be monitored with yellow cups . If more than 50 large rapeseed fleas have been caught with the help of yellow shells within three weeks, control with pyrethroid agents should be carried out in good time at the beginning of October before the eggs are laid, after careful infestation testing. Because of the regionally uneven distribution, yellow peel monitoring of the rapeseed flea is essential before control.
In addition to using the yellow peel , it is also recommended to record the damage caused by the rape plant leaf in order to obtain information on the appearance of the rape flea in the rape field. In Mecklenburg-Western Pomerania , it is also recommended to count the number of rapeseed fleas under the clods in the early morning. The control guideline value is reached when 2–4 beetles per square meter are counted.
Individual evidence
- ↑ Dieter Proff, (Office for Agriculture Ansbach) Control the rapeseed flea! , top agrar 10/2014, s. 69 f.
- ↑ E. Erichsen: Rapserdfloh up to date again. Rape 1/2008, 10-14.
literature
- David V. Alford: Biocontrol of Oilseed Rape Pests. Blackwell Publishing, Oxford 2003, ISBN 0-632-05427-1
