Soil microbes can influence the emissions of plant volatile organic compounds (VOCs), which serve as host-location cues for insect pests and their natural enemies. Agricultural practices steer unique soil microbial communities, but how this influences crop VOCs and subsequent insect attraction remains unknown. The aim of this study was to investigate the effect of diversified agricultural practices on constitutive and herbivore-induced VOC emissions by crops through soil-microbe legacy effects. In a full factorial experiment, we measured VOC emissions by wheat (Triticum aestivum) grown in soil inoculum from wheat-fallow or wheat-cover crop rotations that was subjected to larval feeding by sawflies (Cephus cinctus). Under herbivory, plants grown in cover crop inoculum emitted greater total VOCs, including higher concentrations of 2-pentadecanone, a known insect repellent, and nonanal, a compound important in the recruitment of natural enemies of pests. Plants grown in fallow inoculum showed no differences in VOC emissions whether under herbivory or not. Soil inoculum did not influence VOC emissions of plants in the absence of larval feeding. These results suggest that agricultural practices influence crop VOC emissions through microbe-mediated soil effects. Additionally, crops grown in wheat-fallow rotations may be less successful recruiting natural enemies of pests through herbivore-induced VOC signaling.

The file 'microbesvolatiles.xslx' contains the raw data used in our publication 'Soil microbes alter herbivore-induced volatile emissions in response to cereal cropping systems'. Please see the 'metadata' tabs within the excel file for more detail about the data file.