Bees rise to sweet challenge
GARDENERS have long known the importance of bees for pollination, but the insects can also help flowers to grow bigger and smell more fragrant, scientists have discovered.
Swiss researchers found that plants evolve differently depending on the insect that is pollinating them.
Tests on a type of cabbage species called field mustard, a close relative of oilseed rape, showed that when pollinated by bumblebees, the plants grew three inches taller than with hoverflies in just nine generations.
They also flowered a day earlier and had double the fragrance. And when placed on ultraviolet light, they had more colours that bees can see.
“The traditional assumption is that evolution is a slow process,” Professor Florian Schiestl said. “But a change in the composition of pollinator insects in natural habitats can trigger a rapid evolutionary transformation in plants.”
The change happens because insects differ in their preference for plants. Bees like taller, more fragrant plants, so will seek out and pollinate those more often than shorter, unfragranced varieties, causing the bigger, stronger scented plants to thrive.
Flies are not as effective at pollination and so plants will selfpollinate more often, slowing down the emergence of new traits.
Schiestl said the rapid decline of bee populations could be leading to flowers that do not grow as abundantly or smell as sweet. In the long term, it could reduce genetic diversity of plants, leaving them more susceptible to disease.
Friends of the Earth is encouraging British gardeners to plant bee-friendly gardens as there will be a Great British Bee count in May and June.
They say purple and blue flowering plants are best because they are easier for bees to see and different species prefer different shapes of flower, so a mix of snapdragons, lavender, heathers, sunflowers, wallflowers, yarrow and verbena will attract all kinds.
They are also drawn to shrubs, trees, fruit and vegetables and spring and autumn flowering bulbs.
Bee expert Prof Simon Potts, from the University of Reading, said: “Everyone can help our under-threat bees this spring. Research has shown our towns and cities can be great places for bees – if the right plants are grown in green spaces. With a bit of bee-friendly gardening, and a bit more tolerance of weeds, we can all help to make sure our streets and neighbourhoods are buzzing with these amazing insects.”
Gardeners with lawns are encouraged to leave dandelions and clover to flower for bees, and a “messy corner” of old wood and leaves will provide shelter.
Chemical pesticides should be avoided, especially those containing bee-harming neonicotinoid pesticides.
The research was published in Nature Communications. — The Daily Telegraph