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

Interactions between herbivores and their predators are shaped, in part, by plant phenotype. Consequently, ubiquitous symbionts of plants below-ground, such as arbuscular mycorrhizal fungi (AMF), may influence interactions above-ground prey altering However, the ecological relevance below-ground organisms on predator–prey under field conditions remains unclear. We assessed how AMF herbivore–predator through a experiment. planted two milkweed species (Asclepias curassavica Asclepias incarnata) provided with different amounts inoculum (zero, medium, high) randomized block design. added aphids to reduced predator pressure weekly for 5 weeks evaluate effects recruitment. then allowed re-establish naturally remainder season examine whether AMF-mediated variation recruitment influenced suppression aphid populations. Arbuscular availability soils mediated predaceous midge flies Aphidoletes aphidimyza Aphis nerii, but were species-specific. On A. curassavica, mid-season, midges recruited most strongly medium least high availability. In contrast, each killed fewer increasing density plants, more plants. combination, mortality rates imposed greatest followed zero By comparison, incarnata, was strongest weakest had no effect number per midge, relative density, so mirrored Rates decline populations following recolonization associated densities, well lacewing syrphid which unaffected Therefore, population not simple function AMF–midge interactions. Our findings demonstrate that has pervasive, complex, predator–herbivore dynamics field.