Amy Treonis, Sue Grayston, & Phil Murray

The consumption of roots by insect larvae is an important rhizosphere interaction affecting the quality and quantity of root-derived organic matter in soils.  Root feeding may affect root exudation, biomass, and architecture and converts roots into feces.  These changes should exert a strong influence on the diversity and function of soil microbial communities.  We investigated the impact of feeding by cranefly larvae (Tipula paludosa) on rhizosphere carbon flow and microbial communities in microcosm experiments using soil from an upland grassland in Scotland.  Microcosms were constructed to allow plant growth and collection of rhizodeposits.  Bentgrass (Agrostis capillaris), ryegrass (Lolium perenne) and clover (Trifolium repens) were separately grown in microcosms with and without T. paludosa.  Larvae fed on roots, resulting in changes in the chemistry of collected solutions.  After application of these solutions to soils, changes in the metabolic profiles and structure of the soil microbial communities were assessed using community-level physiological profiling (CLPPs) and phospholipid fatty acid (PLFA) analyses.  Our results suggest that larval root feeding plays a role in structuring soil microbial communities.