Honeybees collect pollen from the buzz-pollinated flowers of invasive Solanum elaeagnifolium in Northern Greece

Around 6% of flowering plants, including most solanaceous species, have flowers specialized for buzz-pollination (sonication). The poricidal anthers of these flowers release pollen in response to frequency-specific vibrations, which buzz-pollinating bees, including bumble bees and many solitary bees, generate via rapid oscillation of flight muscles. Honeybees are incapable of sonication and typically avoid visiting buzz-pollinated plants, although they have previously been observed to scavenge residual pollen from petals of buzz-pollinated flowers in natural settings. Here, we report a novel interaction in which honeybees consistently visit and extract pollen from flowers of Solanum elaeagnifolium (silverleaf nightshade) within a large invasive plant population in Northern Greece. We postulate that honeybee foraging effort on S. elaeagnifolium reflects the shortage of alternative floral resources at the peak of the Mediterranean summer, consistent with observations for pollen-starved bees in captivity. This newly established behavioral shift of honeybees may convey important implications for plant invasions, particularly under climate change, and requires further investigation for untangling its ultimate drivers.