**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE WESTERN CORN ROOTWORM (WCR),DIABROTICA VIRGIFERA, IS THE MOST SERIOUS INSECT PEST OF CORN WORLDWIDE.DAMAGE TO CORN IS PRIMARILY CAUSED BY LARVAE FEEDING ONMAIZEROOTS, CREATING SITES OF MICROBIAL INFECTION, AFFECTINGWATER AND NUTRIENT ABSORPTION, AND PLANT STABILITY.LIKE OTHER INSECTS, WCR LARVAE USE A SOPHISTICATED OLFACTORY SYSTEM TO DIFFERENTIATE HOST FROM NON-HOST PLANTS BASED ON THE BLEND OF VOLATILE ODORANT COMPOUNDS (VOCS) THAT THE PLANTS EMIT. IT'S KNOWN THAT WCR LARVAE ARE ATTRACTED TO MAIZE-PRODUCED CO2FROM FAR DISTANCES AND THAT OTHER VOCS SERVE AS ATTRACTANTS OR REPELLANTS AT CLOSE RANGE.THE GOAL OF THIS PROPOSAL IS TO IDENTIFY THE ODORANT RECEPTORS (ORS) THAT WCR LARVAE USE TO DETECT CRITICAL MAIZE-PRODUCED SEMIOCHEMICALS. PREVIOUSLY WE IDENTIFIED 20 ORS FROM A WCR LARVAL TRANSCRIPTOME WHICH WE WILL EXPRESS IN HEK293 CELLS AND TEST FOR RESPONSIVENESS TO VARIOUS MAIZE-PRODUCED VOCS, INCLUDING KNOWN ATTRACTANTS AND REPELLANTS. THE FUNCTION OF RECEPTORS THAT RESPOND TO ATTRACTANTS OR REPELLANTS IN CELL LINES WILL BE VALIDATED IN RNAI-BASED BEHAVIORAL EXPERIMENTS. THE EFFECTS OF OR GENE KNOCKDOWN ON LARVAL FORAGING BEHAVIOR WILL THEN BE DETERMINED USING ESTABLISHED WCR LARVAE-SPECIFIC BEHAVIORAL ASSAYS.THIS PROPOSAL DIRECTLY ADDRESSES THE PESTS AND BENEFICIAL SPECIES PROGRAM AREA PRIORITY BY UNDERTAKING A MOLECULAR APPROACH TO IMPROVE OUR UNDERSTANDING OF INTERSPECIFIC COMMUNICATION SYSTEMS DIRECTLY RELEVANT TO PEST MANAGEMENT. IN THIS CONTEXT, THE GOAL OF IDENTIFYING MOLECULES INVOLVED IN CHEMICAL COMMUNICATION IN WCR LARVAE WILL ADVANCE OUR KNOWLEDGE OF THEIR OLFACTORY SYSTEM AND ALLOW FOR FUTURE DEVELOPMENT OF BIOLOGICALLY-BASED PEST CONTROL TOOLS.