THE ECOLOGY OF SOIL-DWELLING INSECTS REPRESENTS A BLACK BOX IN OUR UNDERSTANDING OF TERRESTRIAL BIOLOGY. ALTHOUGH INSECTS SUCH AS THE JAPANESE BEETLE (JB) ARE A PROVERBIAL WRENCH IN THE GEARS OF MANAGED ECOSYSTEMS, OUR UNDERSTANDING OF THEIR INTERACTIONS WITH, AND IMPACT ON, SOIL PROCESSES IS MEAGER. IT IS CLEAR THAT OUTBREAKS OF FOLLIAGE-FEEDING INSECTS MAY CAUSE SIGNIFICANT AGRICULTURAL LOSSES, AND EVEN SHORT-TERM DISTURBANCES BY ABOVE-GROUND INSECTS CAN ALTER CARBON, NUTRIENT AND WATER CYCLES. HOWEVER, MATERIAL EVIDENCE OF DIRECT IMPACTS BY BELOW-GROUND INSECTS ON SOIL ECOLOGY IS SPARSE AND LARGELY CORRELATIVE. WE SUGGEST THAT SOME SOIL-INHABITING INSECTS MAY DESTROY SOIL ORGANIC MATTER, MODIFY SOIL STRUCTURE AND ALTER SOIL MICROBIAL COMMUNITIES IN WAYS THAT HAVE LONG-TERM CONSEQUENCES FOR THE SUSTAINABILITY OF AGRICULTURAL SYSTEMS. THE OVERARCHING GOAL OF THIS RESEARCH IS TO GAIN A BETTER UNDERSTANDING OF THE INTERACTIONS BETWEEN SOIL-DWELLING SCARABS (GRUBS) AND THEIR SOIL ENVIRONMENT. IN SUPPORT OF THIS GOAL, THE OBJECTIVES OF THIS APPLICATION ARE TO CHARACTERIZE CHANGES IN SOIL C AND N CYCLING, AND MICROBIAL DYNAMICS RESULTING FROM JB INFESTATION, AND IDENTIFY LINKAGES BETWEEN SOIL AND GUT MICROBES THAT MAY INFLUENCE SOIL BIOGEOCHEMICAL PROCESSES.USING A COMBINATION OF NATURAL AND MANIPULATIVE FIELD EXPERIMENTS WE WILL QUANTIFY THE IMPACT OF JB ON SOIL CO2 AND N2O FLUXAND EXPLORE HOW JB INFLUENCES THE QUANTITY AND QUALITY OF SOIL ORGANIC MATTER. CHANGES TO SOIL ORGANIC MATTER WILL BE LINKED TO FEEDING STRATEGY OF JB USING A NOVEL ORGANIC GEOCHEMICAL TOOL ON JB GUT CONTENTS AND SOIL PARTICULATE ORGANIC MATTER. USING HIGH THROUGHPUT MICROBIAL 16S AND 18S SEQUENCING AND SHOTGUN METAGENOME SEQUENCINGWE WILL QUANTIFY CHANGES IN SOIL MICROBIAL DIVERSITY (BACTERIA, ARCHAEA, AND FUNGI) ASSOCIATED WITH JB INVASION, CHARACTERIZE JB GUT MICROBIOTA, AND QUANTIFY MICROBIAL GENES ASSOCIATED WITH SOIL C AND N CYCLING. WE ANTICIPATE OUR FINDINGS WILL 1) CLARIFY HOW SOIL DWELLING SCARABS INFLUENCE FUNDAMENTAL PROCESSES RELATED TO SOIL HEALTH (C AND N CYCLING),2) IDENTIFY INSECT-GUT MICROBES THAT FACILITATE THE FEEDING BEHAVIOR OF SOIL-DWELLING SCARAB LARVAE, AND 3) IDENTIFYLINKAGES BETWEEN THE LARVAL GUT AND SOIL MICROBES.