**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** FIELD-EVOLVED RESISTANCE TO TRANSGENIC BT CROPS IS A CHALLENGE TO GLOBAL FOOD SECURITY AND SUSTAINABLE PRODUCTION. WESTERN BEAN CUTWORM IS A CRITICAL INSECT PEST THAT ATTACKS CORN AND DRY BEAN CROPS. THIS INSECT HAS EVOLVED RESISTANCE TO THE BT PROTEIN CRY1F, LEAVING VIP3A THE ONLY EFFECTIVE BT TECHNOLOGY FOR THIS PEST. MOST VIP3A TRAITS ARE BLENDED WITH 5% NON-BT REFUGE SEED. HOWEVER, SEED BLENDS CAN IMPACT THE EFFICACY OF INSECT RESISTANCE MANAGEMENT DUE TO CROSS-POLLINATION AND LARVAL MOVEMENT. NUTRITION CAN STRONGLY IMPACT LARVAE CHALLENGED WITH BT PROTEINS; WBC IS DIFFICULT TO MAINTAIN IN COLONY. THEREFORE, ARTIFICIAL DIETS MORE REFLECTIVE OF PLANT-DERIVED NUTRITION AND IMPROVING REARING ARE NEEDED.OBJECTIVES: 1) OPTIMIZE ARTIFICIAL DIET(S) FOR WBC BT SUSCEPTIBILITY MONITORING AND REARING; 2) CHARACTERIZE THE MOVEMENT, DEVELOPMENT, AND SURVIVAL OF WBC LARVAE IN BLENDED VS. BLOCK REFUGES, AND MODEL THE IMPACT ON VIP3A RESISTANCE EVOLUTION; 3) DOCUMENT INSTAR-SPECIFIC BASELINE WBC SUSCEPTIBILITIES TO VIP3A ACROSS ITS HISTORIC (NEBRASKA) AND EXPANDED RANGE (OHIO, MICHIGAN, NEW YORK, ONTARIO), AND PRESUMED SUSCEPTIBLE POPULATION (MEXICO). PERFORMING THIS PROJECT IN CRITICAL WBC GEOGRAPHIES (WESTERN GREAT PLAINS AND GREAT LAKES REGION) ENHANCES THE VALUE OF DATA FOR IRM DECISIONS.IMPACTS: INCREASED UNDERSTANDING OF DYNAMICS WITHIN BLENDED VS. STRUCTURED REFUGES; PREDICTIVE MODELS TO INFORM REGULATORY AGENCY IRM POLICY DECISIONS; DETERMINE AND MONITOR VIP3A SUSCEPTIBILITY LEVELS; OPTIMIZED ARTIFICIAL DIET(S) FOR WBC INSECTICIDAL BIOASSAYS AND REARING; AND ENHANCE STEWARDSHIP OF BT CROPS FOR EAR-FEEDING PESTS. THIS APPLICATION IS ALIGNED WITH THE PROGRAM AREA PRIORITIES TO INFORM REGULATORY DECISIONS BY EVALUATING THE IMPACT OF BLENDED REFUGES AND LARVAL MOVEMENT ON EFFICACY AND STEWARDSHIP OF A KEY TRANSGENIC TRAIT.