Tersilochus obscurator
| Tersilochus obscurator | ||||||||||||
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| Tersilochus obscurator | ||||||||||||
| ( Aubert , 1959) |
Tersilochus obscurator is a hymenoptera fromthe parasitic wasp family (Ichneumonidae).
features
Adult individuals of Tersilochus obscurator are brown-black in color, slightly shiny and about 3.5 to 4 mm long. The eggs are bent into a banana shape, translucent and about 0.39 mm long and 0.11 mm wide.
Occurrence
Tersilochus obscurator is widespread across Europe. The species was also found in Great Britain , Ireland and the Ukraine . After the hibernation, the parasitic wasps appear from mid-April to May. This distinguishes them from the externally hardly distinguishable species Tersilochus microgaster , which appears in the same distribution area as early as the end of March and specializes in the rapeseed flea ( Psylliodes chrysocephala ) as a host.
Way of life
Tersilochus obscurator is a parasitoid of the spotted cabbage weevil ( Ceutorhynchus pallidactylus ) In its way of life, Tersilochus obscurator is very similar to Tersilochus fulvipes , which parasitizes the larvae of the rapeseed weevil ( Ceutorhynchus napi ). At the end of April / beginning of May the parasitic wasps immigrate to the rapeseed fields . The females are looking for the larvae of the spotted carbon Trie Brüsslers ( host larva ), which in the petioles of rape plants minieren . They let themselves be guided by the scents of the plant or the vibrations of the host larvae. As soon as a host larva is found, the female pierces the plant tissue with her ovipositor and lays an egg into the host larva. The larva of Tersilochus obscurator hatches from the egg and does not initially affect the host larvae. Only when the host larva is in the last larval stage does the larva of the parasitoid show a strong increase in growth. The host larva is killed once they are in the ground in a cocoon for Präpuppe has changed. The larva of Tersilochus obscurator then hatches from the dead host larva and spins its own silk cocoon in the cocoon of the host larva. It hibernates there as an adult parasitic wasp ready to hatch. Only one generation is formed each year.
It has not yet been clarified which larval stages of the spotted cabbage weevil are preferred by the parasitic wasp Tersilochus obscurator . Since the ovipositor of the females is limited in length, it is assumed that the larvae of the spotted charcoal weevil are only parasitized while they are in the petioles. When the larvae of the spotted cabbage weevil migrate into the rape shoot, they are probably inaccessible to the parasitoids, as they cannot penetrate the thick rape stem with their short ovipositor.
Multiple occupations of the host larva are possible, ie several eggs can be laid in one host larva by different females of the parasitic wasp ( superparasitization ).
synonym
Thersilochus tripartitus Brischke spp. obscurator Aubert.
supporting documents
Individual evidence
- ^ K. Horstmann: Revision of the European Tersilochinen II (Hym. Ichneumonidae). Spixiana, Supplementum 4, pp. 1-76, 1981
- ↑ H. Barari, AW Ferguson, RW Piper, E. Smith, DLJ Quicke and IH Williams: The separation of two hymenopteran parasitoids, Tersilochus obscurator and Tersilochus microgaster (Ichneumonidae), of stem-mining pests of winter oilseed rape using DNA, morphometric and ecological data. Bulletin of Entomological Research, 95 pp. 299-307, 2005
- ↑ B. Ulber: Parasitoids of Ceutorhynchid Stem Weevils. In: David V. Alford (Ed.): Biocontrol of Oilseed Rape Pests. Blackwell Publishing, Oxford 2003, ISBN 0-632-05427-1
- ↑ a b U. Nissen: Ecological studies on the occurrence of harmful insects and their parasitoids on winter rape in northern German cultivation areas. Dissertation, Christian Albrechts University, Kiel 1997
literature
- David V. Alford: Biocontrol of Oilseed Rape Pests. Blackwell Publishing, Oxford 2003, ISBN 0-632-05427-1