Influence of leaf damage by the horse chestnut leafminer (Cameraria ohridella Deschka & Dimić) on mycorrhiza of Aesculus hippocastanum L.

In many parts of Europe, the white horse chestnut (Aesculus hippocastanum L.) has been attacked by the horse chestnut leafminer (Cameraria ohridella Deschka & Dimić), which causes premature leaf dieback. A. hippocastanum L. establishes mutualistic symbiosis with arbuscular mycorrhizal (AM) fungi. This study involved a comparison of mature A. hippocastanum individuals susceptible to C. ohridella and individuals resistant to this insect after a one-time treatment with a chemical preparation injected into the tree trunks 7 years before the investigation began. Concentration of macronutrients in soil and the activity of soil nonspecific dehydrogenase did not differ between soils under canopies of the treated and untreated trees. Concentrations of C and N were significantly higher in leaves of the treated than those of the untreated trees. The infestation by C. ohridella and defoliation of leaves of the untreated trees did not significantly influence the frequency and intensity of AM colonization compared to the chemically treated trees, although a tendency towards higher average AM colonization of roots of the untreated trees, infested by the herbivores, than roots of the non-infested trees was observed. The results also indicated a tendency for higher biomass of fine roots per soil volume under the trees treated against C. ohridella than under the trees invaded by the insect.