More on Plants, Pollination and Bees

Bees talk to flowers. Talk isn’t strictly correct, as this is not verbal communication, but communicate they definitely do. And if we witnessed the conversation, we would think of it as talking.

Plants carry a very weak negative electrical charge, because although they are rooted in the ground and are therefore earthed, they are exposed to positive electrical charges in the air, making their petals negatively charged. A bee, as she flies through the air, picks up the same positive charge and can sense this as she nears the flower. The pollen will also ‘jump’ from the negatively charged flower to the positively charged bee, just as creating a charge on a balloon will cause hair to stand on end if you hold it near your head.

You can see the crocus pollen grains on the head and thorax of this queen bumblebee

Plants use this charge to encourage or dissuade the bee from landing on it: if a bee has visited, the charge is neutralised, then it builds up again while the plant recharges its nectar supply allowing another bee to detect that flower is open for business. Bees will not visit a flower with no charge, so the insect doesn’t waste energy, and the plants ensure that the flowers in need of pollinating get prioritised.

Plants can fake their response, in that they can adjust their charge to positive even when there is no nectar, but this carries a risk as the pollinators will soon learn this and avoid those blooms. It tends to be a strategy adopted by large, singular flowers which need to ensure they get a visit rather than groups of smaller ones, which need to be careful about crying wolf in case the whole patch gets blacklisted. Bees talk amongst themselves, as well as to plants…

So, when we look at bees foraging, we need to remember that there is a continual dialogue between bee and plant, as the pollinators get redirected towards the most beneficial flowers to maximise the benefits of the symbiotic relationship between insect and plant. The plant will need to assess its moisture content and time its opening hours to coincide with the timetable of the pollinators. Some solitary bees only collect pollen from a particular species or genus of flower, or a handful of similar types. This is known as oligolecty. Honeybees, bumblebees and many solitary bees are polylectic, meaning they are generalists when it comes to foraging, and honeybees are particularly effective as they communicate the whereabouts of good foraging sites to their hivemates.

Five honeybees and a buff-tailed bumble working a clump of crocuses

Bumblebees and solitary bees tend to fly earlier in the day than honeybees, and will work a longer day at the start of the season. Bees watch each other, so will investigate a plant visited by another bee, whatever the species. This is why variety is so important in an ecosystem – they work synergistically so providing food for ALL bees is essential.

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