Year-round behaviour of soil microarthropod communities under plant protection product application.

The use of plant protection products (PPPs) in agro-environments can lead to undesired exposure of non-target organisms in non-target compartments. A year-round field survey was conducted in a vineyard in Northern Italy, for monitoring the changes in the structure of soil microarthropod communities under the application of PPPs, focusing on springtails and mites, both inside and 4 and 10 m outside the vineyard. Exposure to PPPs was estimated as time-weighted average soil concentrations. The fluctuations in the abundances of the different organisms after the application of PPPs, especially insecticides, were recorded. A recovery in abundances was observed at the end of the productive season outside the field and at the beginning of the next spring within the vineyard. Using multivariate statistical tools, the behaviour of each taxon in relation to the stressors was assessed. Some organisms were affected by the stressors, while others were favoured because of low vulnerability to PPPs and the indirect effect of the absence of other taxa. The principal response curves (PRC) method was the most sensitive tool for assessing PPP effects on soil arthropod communities. Strong differences were evident in the structure of the communities inside and outside the vineyard, with the communities sampled 4 and 10 m outside the vineyard being fairly similar, the latter considered as control. The role of physical stressors on community composition is recognised. However, chemical stressors, and in particular PPP exposure seemed to have larger effects on structural and functional characteristics of soil arthropod communities than physical stressors.