Zur Parasitierung von Heuschrecken (Caelifera et Ensifera) durch Larven von Mermis (Nematoda) und Blaesoxipha (Sarcophagidae, Diptera, Insecta) in der Elbaue bei Dessau (Sachsen-Anhalt) nach dem Frühjahrshochwasser 2006

Abstract

Fischer, N., Witsack, W. (2010): Parasitation of grasshoppers (Caelifera et Ensifera) by larvae of Mermis(Nematoda) and Blaesoxipha (Sarcophagidae, Diptera, Insecta) in floodplains near Dessau (Saxony-Anhalt) after the spring flood of 2006. - Hercynia N. F. 44 (2011): 229 – 240.After a spring flood in the river Elbe region in 2006, grasshoppers in floodplain meadows of the BiosphereReserve ‘Flusslandschaft Mittlere Elbe’ were checked for the occurrence of parasitoids. Five speciesof the local grasshopper faunations (15 species) were affected by parasitoids: Chorthippus parallelus,C. biguttulus, C. dorsatus, C. albomarginatus and Stethophyma grossum. Parasitoids from the taxaMermis (Nemathelminthes), Blaesoxipha (Diptera, Sarcophagidae) and larvae of a Tachinidae (Diptera)species played a role in grasshopper parasitation.Mermis depends on a high degree of soil moisture, even in the egg-laying period. Blaesoxipha, however,showed no relation to the flood and was also found in the control meadow. Blaesoxipha can fly in itsadult stage and is widespread in the region.All grasshoppers infected by Mermis were sterile, with the exception of a single C. parallelus femalewith a (low) number of eggs in the ovaries. In contrast, grasshoppers infected by Blaesoxipha showed arather normal fertility. In C. biguttulus (two cases) we found more than a single parasitoid. The parasitoidgeneration cycle is discussed.Key words: Caelifera, Mermis, Blaesoxipha, parasitoid, parasitism, phenology, fertility, soil humidity,inundation meadows