** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** GENETICALLY MODIFIED CROPS INCORPORATING BT TRAITS TARGETING INSECT PESTS ARE WIDELY ADOPTED IN THE US, BUT THEY ARE NOW THREATENED BY THE EVOLUTION OF RESISTANCE. A COMMON METHOD GROWERS CAN USE TO DELAY RESISTANCE IS TO PLANT NON-BT REFUGES, BUT ADOPTION IS LOW. AN EASY WAY TO ENSURE ADOPTION IS TO BLEND NON-BT REFUGE SEED WITH BT SEED (REFUGE IN A BAG, RIB). HOWEVER, THESE PLANTS CAN CROSS POLLINATE IN THE FIELD, POTENTIALLY ACCELERATING THE RATE OF RESISTANCE EVOLUTION FOR EAR-FEEDING PESTS, LIKE HELICOVERPA ZEA. SINCE THERE ARE NO DETAILED STUDIES OF THE EFFECT OF BT ON FIELD-COLLECTED H. ZEA MATING SUCCESS AND BEHAVIOR, OUR PROPOSAL SEEKS TO 1) CHARACTERIZE THE IMPACT OF SEED-BLEND VERSUS STRUCTURED REFUGE ON H. ZEA FEMALE MATING SUCCESS AND FITNESS; 2) CHARACTERIZE THE IMPACT OF SEED-BLEND VERSUS STRUCTURED REFUGE ON H. ZEA MALE ABILITY TO RESPOND TO MATING PHEROMONES BEFORE MATING; 3) CHARACTERIZE THE IMPACT OF SEED-BLEND VERSUS STRUCTURED REFUGE ON H. ZEA MALE SPERMATOPHORE PRODUCTION; AND 4) DEVELOP AMODEL OF RESISTANCE IN H. ZEA TO BT-TOXINS IN THE SOUTHERN U.S. USING INFORMATION GENERATED FROM OBJECTIVES 1-3. OUR MOST IMPORTANT FINDINGS WILL IMPACT THE ASSUMPTION OF THE IMPORTANCE OF NON-BT PLANT REFUGE AND THE ASSUMPTION OF RANDOM MATING IN RESISTANCE MODELS. THIS COULD IMPACT REGULATIONS CONCERNING THE SPATIAL PLACEMENT OF NON-BT HOST REFUGES OR THE ADOPTION OF BLENDED REFUGE TO REPLACE STRUCTURED REFUGE IN SOUTHERN U.S. CORN.