Variable effects of mycorrhizal fungi on predator-prey dynamics under field conditions

1. Interactions between herbivores and their predators are shaped, in part, by plant phenotype. Consequently, ubiquitous symbionts of plants belowground, such as arbuscular mycorrhizal fungi (AMF), may influence interactions aboveground between predators and their prey by altering plant phenotype. However, the ecological relevance of belowground organisms on predator-prey interactions under field conditions remains unclear.

2. We assessed how AMF influence herbivore-predator interactions through a field experiment.

3. We planted two milkweed species (Asclepias curassavica, A. incarnata) provided with different amounts of AMF inoculum (zero, medium, high) in a randomized block design. We added aphids to plants and reduced predator pressure weekly for five weeks to evaluate effects of AMF on predator recruitment. We then allowed herbivore-predator interactions to reestablish naturally for the remainder of the season to examine whether AMF-mediated variation in predator recruitment i...