LEPIDOPTERAN INSECTS ARE AMONG THE MOST IMPORTANT AGRICULTURAL PESTS, AND STRATEGIES FOR CONTROL IN SUSTAINABLE AGRICULTURAL SYSTEMS WILL REQUIRE INTEGRATED BIOLOGICAL APPROACHES. CRITICAL TO SUCH APPROACHES IS AN UNDERSTANDING OF THE INITIAL INTERACTIONS BETWEEN PATHOGENIC MICROBES AND INSECT GUT CELLS. BACULOVIRUSES ARE VIRULENT PATHOGENS OF SOME LEPIDOPTERAN INSECTS BUT THEIR INFECTIONS ARE LIMITED IN THE MIDGUT OF CERTAIN HOST SPECIES, WHICH LIMITS THEIR EFFECTIVENESS AS BIOCONTROL AGENTS. WE AIM TO PERFORM COMPARATIVE TRANSCRIPTOMIC STUDIES OF THESE CRITICAL VIRUS-MIDGUT INTERACTIONS, IN BOTH HIGHLY-PERMISSIVE AND SEMI-PERMISSIVE HOST SPECIES. WE WILL COMPARE INFECTION BY THE BACULOVIRUS ACMNPV IN THE MIDGUT OF A SEMI-PERMISSIVE HOST (HELICOVERPA ZEA) WITH OUR PRIOR STUDIES IN THE PERMISSIVE HOST (TRICHOPLUSIA NI). FOR THESE STUDIES, WE AIM TO: 1) CHARACTERIZE ACMNPV GENE EXPRESSION AND H. ZEA RESPONSES TO INFECTION IN THE MIDGUT; 2) PERFORM A COMPARATIVE ANALYSIS TO IDENTIFY VIRAL GENES AND HOST GENES THAT ARE DIFFERENTIALLY EXPRESSED IN THE FULLY- AND SEMI-PERMISSIVE HOST MIDGUTS; AND 3) EXPERIMENTALLY MODIFY VIRAL AND HOST GENE EXPRESSION TO A) ENHANCE VIRAL REPLICATION IN THE MIDGUT AND SYSTEMIC INFECTION, AND B) NEUTRALIZE HOST GENES THAT MAY RESTRICT ACMNPV INFECTION IN THE SEMI-PERMISSIVE HOST. BY IDENTIFYING VIRAL FACTORS AND HOST RESPONSES INFLUENCING MIDGUT INFECTION, IT WILL BE POSSIBLE TO USE MODIFIED PATHOGENS AND TRANSGENIC PLANTS TO MANIPULATE THIS INTERACTION AND LIMIT THE SEVERITY OF INSECT PESTS USING SUSTAINABLE AGRICULTURAL PRACTICES.