** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** EXOSOMES ARE A TYPE OF EXTRACELLULAR VESICLE THAT PLAY ROLES IN IMMUNITY AND INTERCELLULAR COMMUNICATION BOTH WITHIN AND BETWEEN SPECIES THAT HAVE RECENTLY BECOME A SUBJECT OF INCREASING INTEREST FOR THEIR POTENTIAL AS DELIVERY VEHICLES AND DIAGNOSTIC MARKERS IN MAMMALIAN SYSTEMS. EXOSOMES ROLES IN INSECTS ARE STILL LARGELY UNEXPLORED, BUT PRELIMINARY DATA SUGGEST THAT THEY MAY NOT ONLY SERVE AS CARRIERS FOR THE SYSTEMIC SPREAD OF RNA INTERFERENCE (RNAI) SIGNALS IN INSECTS, BUT ALSO AS A STRATEGY FOR ENHANCING RNAI RESPONSES IN CELLS OF INSECTS THAT SHOW LOW RNAI EFFICIENCY. ACCORDINGLY, WE WILL USE A PAIRED IN VITRO AND IN VIVO MODEL SYSTEM IN SOUTHERN CORN ROOTWORM (SCR, DIABROTICA UNDECIMPUNCTATA) IN COMBINATION WITH RNAI OF RNAI TECHNIQUES AND PHARMACOLOGICAL INHIBITORS TO IDENTIFY THE CRITICAL COMPONENTS THAT ARE REQUIRED FOR EXOSOME FORMATION AND THE SYSTEMIC SPREAD OF RNAI IN CULTURED SCR CELLS AND WHOLE INSECTS. FURTHER, WE WILL DETERMINE THE POTENTIAL OF EXOSOMES TO OVERCOME MECHANISMS THAT LIMIT RNAI EFFICIENCY IN SPODOPTERA FRUGIPERDA, AN INSECT WITH LOW SUSCEPTIBILITY TO RNAI. SCRS ARE AN EXCELLENT MODEL DUE TO THEIR HIGH SUSCEPTIBILITY TO RNAI AND THE AVAILABILITY OF BOTH CELL LINES AND INSECTS. THE PROPOSED RESEARCH WILL SHED LIGHT ON THE ROLES OF EXOSOMES IN RNAI RESPONSES, PROVIDE FUNDAMENTAL KNOWLEDGE ABOUT THE ROLES OF EXOSOMES IN INSECT PHYSIOLOGY, DEMONSTRATE THE POTENTIAL OF EXOSOMES AS DELIVERY VEHICLES FOR INSECT PEST MANAGEMENT, POTENTIALLY IDENTIFY NEW TARGETS FOR INSECT PEST CONTROL, AND SERVE AS A FOUNDATION FOR FUTURE EXPLORATIONS OF THE ROLES OF EXOSOMES IN INSECTS.