GENETICALLY ENGINEERED (GE) CROPS PRODUCING INSECTICIDAL PROTEINS FROM THE BACTERIUM BACILLUS THURINGIENSIS (BT) AS PLANT INCORPORATED PROTECTANTS (PIPS) ARE THE MOST IMPORTANT CONTRIBUTION OF BIOTECHNOLOGY TO PEST CONTROL IN US AGRICULTURE. THE MOST SERIOUS THREAT TO THE SUSTAINABLE USE AND PUBLIC BENEFITS OF BT CROPS IS THE EVOLUTION OF RESISTANCE IN TARGET PESTS. THE VIP3AA TOXIN IS CURRENTLY AN ESSENTIAL BT PIP IN GE CORN AND COTTON TO CONTROL DEVASTATING HELICOVERPA ZEA (CORN EARWORM, CEW) AND SPODOPTERA FRUGIPERDA (FALL ARMYWORM, FAW) LARVAE. EMERGING EVIDENCE SUPPORTS IMMINENCE OF CEW AND FAW RESISTANCE TO VIP3AA PIPS, YET INFORMATION ON FIELD RESISTANCE MECHANISMS OR GENES INVOLVED IS SCARCE.THE GOAL OF THIS PROJECT IS TO RESOLVE THIS KNOWLEDGE GAP BY CAPITALIZING ON AVAILABILITY OF FIELD DERIVED VIP3AA-RESISTANT CEW AND FAW STRAINS TO UNDERSTAND RESISTANCE MECHANISMS AND IDENTIFY RESISTANCE GENES. OBJECTIVES 1 AND 2 WILL TEST ASSOCIATION OF VIP3AA RESISTANCE WITH ALTERED TOXIN PROCESSING IN THE GUT AND BINDING TO RECEPTORS, RESPECTIVELY. OBJECTIVES 3 AND 4 WILL PERFORM A COMPREHENSIVE TRANSCRIPTOMIC ANALYSIS (RNASEQ) TO IDENTIFY VIP3AA RESISTANCE ALLELES IN CEW AND FAW AND ADVANCE ESTIMATION OF THEIR FREQUENCY. EXPECTED OUTCOMES WILL IDENTIFY MECHANISMS AND GENES INVOLVED IN RESISTANCE TO VIP3AA PIPS AS CRUCIAL INFORMATION TO EVALUATE RESISTANCE MANAGEMENT TOOLS THAT SAFEGUARD PUBLIC BENEFITS OF BT PIPS FOR US AGRICULTURE AND GUIDE THE IMPROVEMENT OF BT CROP TECHNOLOGIES.