INSECT POPULATIONS ARE DECLINING WORLDWIDE, AND EXPOSURE TO AGRICULTURAL PESTICIDES IS A MAJOR CONTRIBUTING FACTOR. OFTEN, THIS EXPOSURE DOES NOT CAUSE IMMEDIATE MORTALITY, BUT PRODUCES SUBLETHAL EFFECTS THAT REDUCE THE FITNESS OF NON-TARGET INSECTS BY AFFECTING THEIR ABILITY TO LEARN, FLY, AND THERMOREGULATE. MOST RESEARCH IN THIS AREA HAS FOCUSED ON THE HONEY BEE, NEGLECTING THE ENORMOUS DIVERSITY OF NON-TARGET INSECTS AND THE SPECIFIC LIFE-HISTORY TRAITS THAT DETERMINE THEIR RISK TO PESTICIDE EXPOSURE. A CRUCIAL EVENT IN THE LIFE OF INSECTS IS MATING, WHICH IS PREDOMINATELY REGULATED THROUGH SPECIFIC PHEROMONE BLENDS THAT GUIDE INSECTS TO POTENTIAL MATES AND INDICATE THEIR QUALITY. HOW PESTICIDES AFFECT MATING BEHAVIOR IS UNKNOWN, AND COULD HAVE DISPROPORTIONATELY LARGE IMPACTS ON INSECT FITNESS. TO STUDY THIS, WE CHOSE THE ABUNDANT NATIVE BUMBLE BEE BOMBUS IMPATIENS AS A MODEL, AND THE NEONICITINOID PESTICIDE IMIDACLOPRID. OUR PRELIMINARY DATA SUGGEST THAT MALES PREFER QUEENS NOT EXPOSED TO IMIDACLOPRID, VIA AN UNKNOWN MECHANISM. HERE I PROPOSE THAT EXPOSURE TO IMIDACLOPRID DETRIMENTALLY AFFECTS MATING BEHAVIOR, AND DESCRIBE EXPERIMENTS TO DETERMINE POSSIBLE MECHANISMS. IN OBJECTIVE 1, I WILL EXAMINE IF MATING BEHAVIOR IS AFFECTED FOLLOWING SUBLETHAL EXPOSURE TO ENVIRONMENTALLY RELEVANT DOSES OF IMIDACLOPRID. IN OBJECTIVE 2, I WILL DETERMINE IF THE IMPACT ON MATING BEHAVIOR IS DUE TO IMPAIRED PHEROMONE PRODUCTION AND PERCEPTION. IN OBJECTIVE 3, I WILL EXAMINE THE PHYSIOLOGICAL MECHANISMS MEDIATING SUBLETHAL EFFECTS ON MATING BEHAVIOR (SPERM VIABILITY, LIPID CONTENT, COLD TOLERANCE). UNDERSTANDING HOW PESTICIDE EXPOSURE AFFECTS INSECT MATING WILL INFORM PESTICIDE USE AND GUIDE THE DEVELOPMENT OF POSSIBLE REMEDIES.