Aboveground and Belowground Insect Herbivory Changes Maize-Wireworm Interactions via Root Volatile Cues

The rhizosphere harbours critical plant-herbivore interactions often mediated by small lipophilic molecules (SLMs). Despite the agricultural importance of many soil-dwelling insects, surprisingly little is known about chemically mediated belowground crop-pest interactions. Root and shoot herbivores can influence these interactions by modifying the chemistry of their shared host, thereby influencing interactions with other organisms across trophic levels. We combined laboratory, semi-field and field-based experiments to determine whether single and simultaneous above and belowground herbivory affects the olfactory orientation of soil-dwelling Agriotes wireworms towards maize roots. Different herbivore combinations produced distinct SLM profiles, and wireworms were most significantly attracted to the roots of plants under dual herbivory (wireworms + Ostrinia nubilalis larvae on leaves). A synthetic SLM blend, characteristic of dual herbivory, was significantly attractive in semi-field and field environments. These findings highlight the ecological significance of systematically induced SLMs in shaping interactions between a generalist belowground pest and its host plant.