Effect of contaminated soil on multitrophic interactions in a terrestrial system

Abstract

The effect of contaminated soil on multitrophic interactions in a terrestrial system was studied in a mesocosm experiment with European beech, larvae of summer chafer, and entomopathogenic nematodes (EPN). Beech seedlings were grown in non-contaminated forest and garden soil contaminated with potential toxic elements Cd, Pb and Zn, and in the absence/presence of summer chafer larvae. Root morphology and ectomycorrhizal communities were analysed. Volatile organic compounds (VOC) emitted from beech roots were investigated by GC-MS. Humulene, β-caryophyllene, borneol and camphor were selected for chemotaxis assay with EPN Steinernema feltiae, S. carpocapsae and Heterorhabditis bacteriophora. Increased root tip density was observed as a response to soil contamination and root herbivory. Soil contamination decreased ectomycorrhizal species richness. Analyses of VOC yielded 14 different compounds. Results showed that the least mobile nematode species towards the VOC tested was S. feltiae. β-caryophyllene was an attractant for S. carpocapsae and humulene a weak attractant for H. bacteriophora. Beech roots emitted VOC that affected movement of EPN. β-caryophyllene was detected in beech roots regardless of treatment, indicating that VOC that affect movement of EPN are emitted even in the absence of direct root herbivore attack.