Urbanization can alter soil chemistry, potentially influencing floral nectar composition and pollinator foraging behavior. We examined how two micronutrients commonly associated with urban environments, sodium (Na⁺) and potassium (K⁺), affect pollinator foraging. We conducted 10-minute field observations of pollinator visitation to flowering plants in urban areas on flowers supplemented with nectar (sugar water (15%), with Na⁺ or with K⁺).Next, we performed laboratory foraging studies with butterflies (Vanessa cardui) and bumble bees (Bombus impatiens). Individuals were introduced to a foraging arena containing nectar sources with randomly assigned treatments (sugar water, with Na⁺, or with K⁺). The butterflies foraged from artificial flowers, and bumble bees from blue plastic chips each containing nectar, with treatment placement randomized each trial. Foraging activity was recorded using a video camera, and individuals were allowed to forage for 30 minutes. Afterward, recordings were annotated to quantify foraging activity.To date, we have conducted 15 field observations and 39 butterfly trials; the bumble bee trials are ongoing. We expect differences in visitation and nectar preference among treatments in both field and laboratory settings, including variation between butterflies and bumble bees. This work highlights both the ecological importance of nectar micronutrients and the importance of studying pollinator behavior.
