PROTEINS FROM THE SOIL BACTERIUM BACILLUS THURINGIENSIS (B.T.) OFFER HIGH SPECIFICITY IN INSECT TOXICITY. GENES THAT INDUCE CROP PLANTS TO EXPRESS THESE INSECTICIDAL PROTEINS HAVE BEEN SUCCESSFULLY INSERTED INTO CORN AND COTTON. THE VAST MAJORITY OF CORN (OVER 80%) PLANTED IN THE US EXPRESSES AT LEAST ONE BT TOXIN FOR INSECT MANAGEMENT. WHILE THIS APPROACH HAS LARGELY BEEN SUCCESSFUL ON A NUMBER OF FRONTS, PROBLEMS WITH RESISTANCE DEVELOPMENT BY TARGET PESTS ARE A CONSTANT THREAT, AS THEY ARE WITH CONSTANT EXPOSURE TO ANY PEST MANAGEMENT APPROACH.INSECT RESISTANCE MANAGEMENT PLANS HAVE BEEN IMPLEMENTED TO DELAY THE ONSET OF RESISTANCE TARGETING THE CORN ROOTWORM COMPLEX. A MANDATORY REFUGE THAT CONSISTS OF CORN PLANTS THAT DO NOT EXPRESS THE BT TOXIN MUST BE PART OF EVERY BT CORN PLANTING. THIS ENSURES THAT SUSCEPTIBLE INSECTS WILL ALWAYS BE PRESENT TO MATE WITH ANY THAT SURVIVE BT EXPOSURE - EFFECTIVELY "DILUTING" THE POPULATION OF RESISTANT INSECTS. IN OTHER WORDS, THIS APPROACH SEEKS TO HAVE ABUNDANT, SUSCEPTIBLE, INSECTS FROM REFUGE PLANTS WITHOUT THE PEST-SPECIFIC TOXIN MATING WITH RELATIVELY RARE, RESISTANT, INSECTS FROM TOXIN-PRODUCING PLANTS ("BT" PLANTS). HOWEVER, PRIOR RESEARCH FROM OUR GROUP ON THE KEY PEST OF CORN, THE WESTERN CORN ROOTWORM (WCR), SHOWED THAT THE NUMBERS OF INSECTS GENERATED IN CURRENTLY IMPLEMENTED REFUGES ARE INSUFFICIENT TO MATE WITH THOSE EMERGING FROM BT CORN IN THE SAME FIELD. ONE POSSIBLE FACTOR LIMITING ADULT EMERGENCE FROM REFUGE PLANTS ARE THE NEONICOTINOID INSECTICIDES APPLIED TO SEED. CURRENTLY, ALL BT CORN IS SOLD WITH NEONICOTINOID SEED TREATMENTS (NSTS).DESPITE THIS WIDESPREAD USE, THE CONTRIBUTION OF NSTS TO CORN ROOTWORM CONTROL (INCLUDING RESISTANCE MANAGEMENT) IN BT CORN IS COMPLETELY UNKNOWN. FOR EXAMPLE, THE INSECTICIDE MAY BE DETRIMENTAL TO RESISTANCE MANAGEMENT, BY CAUSING MORTALITY IN THE REFUGE INSECTS THAT WE ARE TRYING TO PRESERVE. ON THE OTHER HAND, THERE ARE OTHER, NON-ROOTWORM SOIL PESTS THAT CAN BE EFFECTIVELY MANAGED WITH NSTS. WE WILL EXAMINE THE ECONOMIC NEED FOR NSTS TO PREVENT ROOT INJURY AND YIELD LOSS FROM SOIL INSECTS IN TWO ECOLOGICALLY DISTINCT STATES WHERE ROOT FEEDING INSECT PESTS ROUTINELY OCCUR, INDIANA AND VIRGINIA.ASIDE FROM HYBRID DIFFERENCES, MOST CORN IN THE US IS GROWN USING VERY SIMILAR APPROACHES - BOTH EXPRESSING BT TOXINS AND USING NSTS. HOWEVER, THE BELOW-GROUND PEST COMPLEXES ARE VERY DIFFERENT: CORN ROOTWORMS DICTATE PEST MANAGEMENT IN INDIANA, WHEREAS WIREWORMS, WHITE GRUBS, AND ROOTWORMS ARE CONCERNS IN VIRGINIA. WHILE ABUNDANT DATA ON ENVIRONMENTAL IMPACTS EXIST FOR BT PRODUCTS, THE COSTS/BENEFITS OF PERSISTENT NST RESIDUES ON SOIL HEALTH HAVE NOT BEEN MEASURED - OBJECTIVE 1 OF OUR PROPOSED WORK WILL FILL THIS INFORMATION GAP. USING NOVEL METHODS DEVELOPED BY OUR GROUP, WE WILL MEASURE ROOTWORM EMERGENCE FROM REFUGES WITH AND WITHOUT NSTS, THEN CHARACTERIZE THE VALUE OF THE CONTROL NSTS PROVIDE BY COMPLEMENTING INSECT-RESISTANT BT MAIZE HYBRIDS. DURING OBJECTIVE 2, WE WILL COLLECT DATA ON INSECTICIDE RESIDUES IN SOIL AND WATER IN THESE EXPERIMENTS. WE HYPOTHESIZE THAT NSTS CAN BE REMOVED FROM GM CORN SEEDS GROWN IN SOME REGIONS WITHOUT INCREASE IN PEST DAMAGE OR DIMINISHED REFUGE FUNCTION (I.E., NUMBER OF INSECTS PRODUCED FROM REFUGE PLANTS). FURTHER, WE HYPOTHESIZE THAT REMOVING NSTS WILL HAVE THE POTENTIAL FOR A BENEFICIAL EFFECT UPON SOIL AND WATERSHED HEALTH VIA REDUCED RESIDUES. THE OVERALL GOAL OF THIS RESEARCH IS TO PROVIDE INFORMATION TO GUIDE THE USE OF NSTS IN A WAY THAT DOES NOT COMPROMISE REFUGE FUNCTION, WHILE PROVIDING GROWERS PROTECTION FROM ROOT-FEEDING PESTS WHERE APPROPRIATE. REDUCTIONS OF LEVELS OF PESTICIDE IN SOIL IS A STATED GOAL OF THE 2017 BRAG PROGRAM AS WELL. THE PROPOSED WORK IS DIRECTLY APPLICABLE TO THE FOLLOWING SPECIFIED AREAS FROM THE BRAG 2017 RFA: ENVIRONMENTAL IMPACTS OF GE RELATIVE TO NON-GE ORGANISMS IN THE CONTEXT OF PRODUCTION SYSTEMSC) COMPARATIVE ASSESSMENT OF ENVIRONMENTAL IMPACTS OF AGRICULTURALPRODUCTION SYSTEMS USING ORGANIC AND/OR CONVENTIONAL METHODS WITH THOSE INVOLVING PLANT, ANIMAL, OR BIOTECHNOLOGY.