** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** RNA INTERFERENCE (RNAI), A NATURALLY OCCURRING PROCESS IN MOST EUKARYOTIC ORGANISMS, HAS SHOWN ENORMOUS POTENTIALS FOR SPECIES-SPECIFIC MANAGEMENT OF INSECT PESTS. HOWEVER, DEVELOPING RNAI-BASED PEST MANAGEMENT STRATEGIES HAS BEEN CHALLENGED BY LOW OR LACK OF RNAI EFFICIENCY OF SMALL INTERFERING RNA (SIRNA) DELIVERED INTO INSECTS. THE OVERALL GOAL OF THIS PROJECT IS TO DEVELOP SIRNA-BASED SPRAYABLE FORMULATIONS AND BAITS THROUGH RATIONAL DESIGN OF EFFECTIVE SIRNA CONSTRUCTS AND DEVELOPMENT OF NEW STRATEGIES TO OVERCOME THE MAJOR CHALLENGES TOWARD THE WIDESPREAD APPLICATION OF SIRNA FOR INSECT PEST MANAGEMENT. WE HYPOTHESIZE THAT LOW OR LACK OF RNAI EFFICIENCY OF SIRNA IS CAUSED BY THE APPLICATION OF INEFFECTIVE SYNTHETIC SIRNA, RAPID DEGRADATION OF SIRNA BY EXORIBONUCLEASES (EXORNASES), LOW CELLULAR UPTAKE OF SIRNA, AND ENDOSOMAL ENTRAPMENT OF SIRNA IN INSECTS. TO TEST THESE HYPOTHESES, WE PLAN TO DEVELOP NOVEL STRATEGIES FOR DESIGNING HIGHLY EFFECTIVE SIRNA CONSTRUCTS BASED ON THE ABUNDANCE OF THE SIRNA ANTISENSE STRANDS GENERATED BY INSECT SPECIES-SPECIFIC DICER-2. WE WILL THEN USE EXORNASE INHIBITORS, EXORNASE-RESISTANT SIRNA CONSTRUCTS, AND SIRNA MIXTURES TO PROTECT SIRNA FROM EXORNASE-MEDIATED DEGRADATION. FINALLY, WE WILL DEVELOP SIRNA NANOPARTICLE-BASED DELIVERY STRATEGIES TO ENHANCE CELLULAR UPTAKE OF SIRNA, AND TEST ENDOSOMAL ESCAPE ENHANCING AND ENDOSOME-DISRUPTING AGENTS TO PROMOTE ENDOSOMAL RELEASE OF SIRNA. THIS PROJECT WILL ADVANCE OUR KNOWLEDGE ON THE MECHANISMS AFFECTING RNAI EFFICIENCY OF SIRNA IN INSECTS AND DEVELOP NEW STRATEGIES TO OVERCOME THE MAJOR OBSTACLES TOWARD SUCCESSFUL APPLICATION OF SIRNA FOR INSECT PEST MANAGEMENT. THIS PROJECT ADDRESSES PROGRAM AREA PRIORITY (A1112): PESTS AND BENEFICIAL SPECIES IN AGRICULTURAL PRODUCTION SYSTEMS.