In this project the PIs will study the critical relationship between food resources provided by flowers and decisions made by pollinators on foraging. Flowers attract pollinators by offering different food sources, pollen and nectar. Understanding how these floral rewards influence bee behavior is key for conserving ecologically and agriculturally important pollination mutualisms. Most previous research on floral rewards has focused on nectar, bees' source of carbohydrates. However, bees also consume pollen from many plant species, gaining the protein needed for egg production, larval development, and survival. While many plant species chemically or physically protect their pollen from consumption, 8-10% offer pollen itself as a reward. Collection of pollen rewards often requires a technique called sonication or "buzz pollination." During sonication, bees rapidly contract their flight muscles, producing strong vibrations that forcibly expel pollen.
This study will reveal how the nutritional composition of floral rewards (e.g. carbohydrate/nectar vs. protein/pollen) influence individual bees, propensity to specialize on flower types. Such specialization is critical to plant reproductive success because it transfers pollen to conspecifics. Further, given evidence that nutritional factors contribute to pollinator declines, it is important to understand how bees specialize on particular nutrients in relation to colony needs. Yet, little is known about how bees' propensity to specialize depends upon whether a flower offers only nectar, only pollen, or both. Further, it is unknown whether energetically expensive collection routines, such as sonication, influence specialization. Behavioral experiments will help understand how reward composition and handling costs affect bee and plant fitness. Untangling the connections between bumble bees' nutritional state, floral morphology, and reward composition will provide a better understanding of the foraging patterns of these native, economically important pollinator species, widely in decline. The research will involve outreach including a native bee identification workshop and web resource developed in parallel will promote understanding of these questions both within and beyond the scientific community. Many economically important crops, such as tomatoes, eggplants, blueberries, and kiwifruit are buzz pollinated by native bees.
