Annual carbon flux through soil respiration is ten times greater than fossil fuel combustion, but its component parts are poorly understood because they are the product of complex multitrophic interactions between soil organisms. A major component of carbon flux from plants to soil occurs through networks of symbiotic arbuscular mycorrhizal fungi. Here, using 13CO2 pulse labeling, we show that natural densities of the numerically dominant fungal feeding invertebrate Protaphorura armata (order Collembola) reduces 13C enrichment of mycorrhizosphere respiration by 32%. Our findings emphasize the importance of multitrophic interactions in regulating respiration of recent plant photosynthate from soil.