Flowers have many ways to signal to insects which flowers have pollen, for example by color, scent and even changes in electrical current.
Some bees prefer purple to other colors. (Photo: Andrew Graham/Getty Images).
When pollinating insects land on a flower, they perform a mission: to find sweet nectar to eat and to store other nutritious pollen grains to bring back to their young.
But how do they know where to find pollen?
In theory, this is very simple: a flower emits tiny, fragrant, delicious dust particles that they see right in their sight, helping them know to immediately fly there. But the reality is much different than that.
Biologist Casper van der Kooi at the University of Groningen, the Netherlands – an expert in research on flower color evolution – said that for plants, pollen is for reproduction. The purpose of creating this powder is to spread the gametes or reproductive cells of one flower to another to create life.
That’s why plants need the help of pollinating insects. Producing pollen requires a lot of energy and nutrients, so if insects eat all the pollen or the flower encounters the wrong pollinator, the energy the plant produces for reproductive purposes becomes useless. .
Therefore, for most plants, pollen is hidden, making it more difficult for insects to find it. But plants cannot “hide” pollen, because if they did, insects would no longer visit.
Therefore, instead of signaling directly to insects, plants often use faint signals to broadcast information so that insects can detect certain signals and decide to visit the species. Which flower?
Visual signals are one of the main forms of communication between plants and pollinating insects. Flowers come in many colors and insects have an innate connection to colorful things.
Some flowers also have nectar guides, i.e. patterns visible only in the ultraviolet spectrum, to illuminate pathways leading to nectar and pollen for insects to follow. There have been many studies that show that these nectar instructions as well as the color of the flower can change when pollen and nectar decrease, for example, iridescent flowers will change color from yellow to red.
Scent is also a guide to pollen count. Flowers release all sorts of chemical compounds into the air and insects can pick up on these olfactory signals. Some plants can regulate the amount of chemicals they emit as an additional signal. For example, blueberry flowers have evolved to emit less scent after being pollinated.
Pollinating insects can also detect other subtle signals. A very interesting example is the electric field. Flowers have a very weak electric field and are affected by the shape of the flower. This electric field can also be disrupted after a visit from an insect. Research has shown that bumblebees and some other insects can detect flowers that have lost their electric fields thanks to sensors in their special hairs.
But ultimately, the way insects decide where to find pollen varies greatly depending on the species’ characteristics. Flowers may also have evolved to create suitable relationships with their beneficial pollinators and influence how the insects make their pollen-finding choices.
Some flowers, like dandelions, leave their pollen in visible places, attracting many pollinating insects. Meanwhile, tomato flowers, which rely solely on bees for pollination, hide pollen in their structures to attract only these insects.
Additionally, different insects are also attracted to different colors. For example, flies often like yellow, while bees like blue…
Even deciding which flower is most attractive depends on the individual insect. Individual insects in a colony may make different decisions depending on their experience of their surroundings.
