WILD BEES ARE ECOLOGICALLY AND ECONOMICALLY CRITICAL POLLINATORS, WHO NOT ONLY ENHANCE THE POLLINATION SERVICES OF HONEYBEES, BUT WHO ARE ALSO CAPABLE OF MORE EFFECTIVELY POLLINATING CERTAIN CROPS. IN LIGHT OF THEIR VALUE TO FOOD SECURITY, RECENT DECLINES OF SEVERAL WILD BEE TAXA ARE A MAJOR AGRICULTURAL CONCERN. DISRUPTIONS TO THE NUTRITIONAL RESOURCES AVAILABLE TO BEES ARE A POTENTIAL DRIVER OF THESE DECLINES. BESIDES DIRECT IMPACTS ON GROWTH AND SURVIVAL, NUTRITION LIKELY ALSO HAS INTERACTIVE EFFECTS, GIVEN ITS ROLE IN MEDIATING RESPONSES TO OTHER STRESSORS, SUCH AS PESTICIDES AND PATHOGENS. WE PLAN TO EXPLORE HOW NUTRITION AND PESTICIDES COMBINE TO AFFECT THE HEALTH AND PERFORMANCE OF BUMBLEBEES, THROUGH A SERIES OF LAB-, GREENHOUSE- AND FIELD-BASED EXPERIMENTS. WE FOCUS ON NEONICOTINOIDS, THE MOST POPULAR CLASS OF SYSTEMIC PESTICIDES, FOUND IN THE NECTAR AND POLLEN OF CROPS, HORTICULTURAL PLANTS, AND WILDFLOWERS.WE ASK HOW NEONICOTINOIDS AFFECT 1) THE NUTRITIONAL VALUE OF POLLEN AND NECTAR 2) BEES' ABILITY TO ASSESS THESE REWARDS AND 3) BEES' ABILITY TO REGULATE THE COLONY'S INTAKE OF DIFFERENT RESOURCES IN RELATION TO NUTRITIONAL NEED. WE COMBINE BEHAVIORAL AND ELECTROPHYSIOLOGICAL TECHNIQUES TO IDENTIFY DISRUPTIONS TO THE SENSES OF SMELL AND TASTE THAT BEES (SUCH AS BUMBLEBEES, MASON BEES, AND SQUASH BEES) USE TO ASSESS NECTAR AND POLLEN AND COMMUNICATE INFORMATION ABOUT THESE RESOURCES WITH COLONYMATES. BEYOND IDENTIFYING THE SENSORY MECHANISMS LINKING PESTICIDE EXPOSURE TO NUTRITIONAL CONSEQUENCES, WE ASK HOW THESE DISRUPTIONS SCALE UP TO AFFECT COLONY-LEVEL SURVIVAL. FINALLY, WE ASK HOW COMMON WEED AND HEDGEROW PLANT SPECIES VARY IN THEIR UPDAKE OF THESE SYSTEMIC PESTICIDES, WHICH TRANSIT THROUGH SOIL AND WATER TO AFFECT NON-CROP PLANTS. WE THUS WILL IDENTIFY A BASIC MECHANISM BY WHICH SYSTEMIC PESTICIDES ALTER NUTRITIONAL REGULATION, AN INTERACTION BETWEEN TWO FACTORS IMPLICATED SEPARATELY IN THE DECLINE OF WILD AND MANAGED BEES.STUDY OF NEONICOTINOIDS IS RELEVANT NOT ONLY TO THE HONEYBEES THAT PROVIDE &GT; $15 BILLION IN ECONOMIC VALUE FOR THE U.S. ANNUALLY BUT ALSO TO THE NATIVE BEES AND OTHER INSECTS THAT PROVIDE AN ESTIMATED $2-3 BILLION IN ANNUAL POLLINATION. GIVEN MISMATCH BETWEEN HONEYBEE SUPPLY AND AGRICULTURAL DEMAND THE PERSISTENCE OF WILD POLLINATORS IS CRITICAL TO THE LONG-TERM SECURITY OF THE U.S. FOOD SUPPLY. THESE WILD BEES CAN ENHANCE YIELDS, AND POLLINATE CERTAIN CROPS MORE EFFECTIVELY THAN HONEYBEES. ALTHOUGH WE LARGELY FOCUS ON BOMBUS IMPATIENS AS A TRACTABLE MODEL FOR WILD BOMBUS, OUR APPROACH IS RELEVANT TO UNDERSTANDING HOW NEONICOTINOIDS MIGHT ALSO IMPACT OTHER POLLINATORS IN AGROECOSYSTEMS (AND BACKYARDS), SUCH AS SOLITARY BEES, FLIES, BEETLES, AND BUTTERFLIES.