Epigeous predatory arthropods in winter wheat crops in Central Germany und their relationship to aphids
1944
Volkmar, C. (Martin-Luther-Univ., Halle-Wittenberg (Germany)) | Bothe, S. | Kreuter, T. | Luebke-Al Hussein, M. | Richter, L. | Heimbach, U. | Wetzel, T.
An increased occurrence of eurychoric spider species, in literature described as typical for agroecosystems, was proven in a 2-year study for the sites Hoetzum, Peissen and Barnstaedt. In Hoetzum 55 species (n = 15.257) were identified, in Peissen 73 (n = 15.802) and in Barnstaedt 50 (n = 10.283). Barber traps helped to prove the presence of the main spider species (Oedothorax apicatus, Erigone atra et al.) throughout the whole sampling period. The intensest activities of the lycosids which - beside linyphiids - were the most frequent family in the pitfall trap catches was observed in the month of May. A good survey about the spider species living in the biomass above the ground and close to the surface was obtained by use of photoeclectors. When the capturing extended over 2 weeks the hatching of young spiders was found to have greater influence on the sampling result than weekly trap renewal. Higher dominance rates compared with pitfall traps were recorded for species of the family Theridiidae as well as of the linyphiid species Meioneta rurestris, Porrhomma microphthalmum and the Lepthyphanantes tenuis group. The composition of the spider community revealed clear differences between pitfall trap catches and D-Vac sampling. In D-Vac suction traps young spiders dominated. It should be noted tha lycosids were hardly recorded, neither with the D-Vac nor the phoroeclector. Spiders and especially linyphiids and lycosids belong to the most important antagonists of insect populations in agrocoenoses. Spiders deserve to be paid attention as predator group, also for the reason that in cereal crops they may sometimes be found in large numbers over longer periods (x = 50 - 100 individuals per spuare metre)
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