Whenever I encounter evening primrose plants in bloom, I watch
them for a while. These native plants attract a variety of bees and other
pollinators. At night, evening primrose is highly attractive to large moths. In
the early hours of the morning, fast flying blue orchard bees visit the yellow flowers.
Later in the day, butterflies, honey bees, flies, and other insects actively forage
evening primrose. In today’s photo a honey bee collects nectar from evening
primrose.
Honey bees can detect differences in nectar sugar
concentrations of one to three percent, and foraging worker bees seek those nectar
sources with the greatest concentrations of sugars. Lilach Hadany, a researcher
at Tel Aviv University, questioned whether plants could hear sounds similarly
to animals, https://www.nationalgeographic.com/science/2019/01/flowers-can-hear-bees-and-make-their-nectar-sweeter/.
Hadany’s findings reveal that at least one plant, evening primrose, responds to
the vibrations of pollinators’ wings. Within minutes of exposure to vibrations
in the range of honey bee wing beats (0.2 to 0.5 kilohertz), evening primrose
increased the concentration of sugars in its nectar. Hadany’s lab found that
within three minutes of exposure to honey bee wing-beat-frequency vibrations
the plants increased the nectar sugar concentrations from between 12 and 17
percent to 20 percent. In field observations, her researchers found pollinators
around evening primrose plants nine times more frequently after the plants were
visited within the past six minutes. The resulting sweeter nectar is naturally
more attractive to bees and other pollinators. Since flowering plants, such as
evening primrose, depend upon insect pollination for reproduction, any plant
that attracts more pollinators has a reproductive advantage. Evening primrose
flower petals are shaped like an open bowl. Such shapes concentrate and
increase vibrations. The researchers at the Tel Aviv lab found that evening
primrose flowers concentrated vibrations of the frequency range of honey bees.
The ability of a flowering plant to increase its nectar’s sugar concentration
would make it more attractive to pollinators and more likely to be pollinated,
the first step in the plant’s reproduction.
--Richard
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