Soil predatory mite communities (Acari: Gamasina) in agroecosystems of Central Argentina

The objective of this study was to compare soil predatory mite communities over a gradient of land use intensity in agroecosystems of Central Argentina. The study was conducted at La Colacha basin, Córdoba, Argentina on coarse-loamy, illitic, thermic Typic Hapludoll. Four sites with different management systems (natural grassland, cattle raising, arable and mixed), but with the same Soil Series, similar geomorphological characteristics and the same land use history until 50 years before, were sampled at four sampling dates. Thirty-eight species, 19 genera and nine families were identified. Ninety-two percent of the identified species are new to science. This shows that the taxonomic knowledge of Gamasina is poorly developed in Argentina. In this study, Gamasina community structure was clearly influenced by the management type. This confirms our hypothesis that Gamasina community structure significantly changes as material and energy inputs and mechanical perturbations in the system increased from the natural soil to the conventional agricultural sites. The effects of agricultural practices could be observed in the occurrence of the species, the diversity and the dominance structure of the community, the maturity index, and also in seven similarity measures and the multivariate canonical correspondence analysis (CCA). Species number and diversity measures were highest in the cattle raising plot and very low in the natural and arable site. So, in terms of species number, the arable field did not have an impoverished community in comparison with the natural undisturbed grassland.