Do nocturnal pollinators carry a more conspecific pollen load than diurnal ones?

Plant-pollinator interactions are key for the reproduction of wild plants and for food security. However, the role nocturnal pollinators play in wild plant communities is not yet clear. Specifically, it has rarely been studied whether nocturnal pollinators are comparable to diurnal ones in the pollination services they deliver in plant communities. We tested whether nocturnal pollinators have the potential to provide higher pollination services than diurnal ones by carrying a more conspecific pollen load. We compared pollen loads carried by nocturnal and diurnal pollinators captured over 24-hour cycles in co-flowering plant communities in European ruderal meadows. Pollen load was less diverse at night, and the proportion of conspecific pollen carried by nocturnal pollinators was similar to or higher than that of diurnal ones. Thus, nocturnal pollinators do not only carry pollen but can remove and deposit conspecific pollen with a comparable or even superior performance to diurnal ones. Therefore, nocturnal pollinators can be more efficient pollination vectors than diurnal ones, which might compensate their lower pollen load.