The role of epigeic macroarthropod predators in the regulation of abundance and biomass of saprophagous nematodes on grass litter of meadow

Research hypothesis supposed that: 1) microbes, saprophagous nematodes and predacious, epigeic macroarthropods could create the aboveground, detrital food web of meadow; 2) in such food web the top-down regulation of abundance and biomass of saprophagous nematodes and microbes take place in a way predicted by trophic-dynamic theory. A field experiment with manipulation of macroarthropod predators abundance as a method in order to test this hypothesis was chosen. The results were quite opposite to the supposition of the trophic-dynamic theory. Exclusion of epigeic macroarthropods from the supposed food-web results in decreased abundance and biomass of nematodes and increased abundance of bacteria considered as entity. However, it was evident that the top-down regulation of nematode abundance exists there, but its mode is rather behavioral than trophic. Trophic interactions between predacious macroarthropods and nematodes has not been observed there. The macroarthropods served as the transport for the nematodes. In such way they could regulate the initial number of nematodes which colonized the litter.