Wednesday, April 25, 2012

Bees love purple

Isn't it fun to learn that bees love purple? Scientists who discover such wonderful things make my heart happy. Our gardens can become oases for pollinators. The following article gives more details on how the bees' choose colors.

"A bee’s favorite color can help it to find more food from the flowers in their environment, according to new research from Queen Mary, University of London.

Dr Nigel Raine and Professor Lars Chittka from Queen Mary’s School of Biological and Chemical Sciences studied nine bumblebee (Bombus terrestris) colonies from southern Germany, and found that the colonies which favored purple blooms were more successful foragers.

Dr Raine explains: “In the area we studied, violet flowers produced the most nectar - far more than the next most rewarding flower color (blue). Inexperienced bees are known to have strong color preferences, so we investigated whether the bumblebee colonies with a stronger preference for violet flowers foraged more successfully in their local flora.”

Bumblebee visiting nectar-rich flowers (Vicia spp.)Photographer: Tom Ings

The team first observed the color preferences of naïve bees (those which had never before seen flowers) using violet (bee UV-blue) and blue (bee blue) artificial flowers in the laboratory. They then observed the rate at which bees from the same colonies collected nectar from real flowers in the wild.

The results showed that the colonies who preferred violet to blue flowers in the laboratory, harvested more nectar from real flowers under field conditions. In fact the colony with the strongest preference for violet (over blue) brought in 41 per cent more nectar than the colony with the least strong bias.

The team’s findings suggest that bumblebees have developed their favorite color over time, to coincide with the most profitable, nectar-rich flowers available.

It has been long accepted that animals show innate preferences when selecting a mate, but little research has been carried out on how such sensory biases affect foraging habits. The researchers believe their work could have implications for other species.

“A straw poll of friends always reveals many personal differences in 'favorite color'. Some human societies also have very different color preferences,” explains Raine. “In our work on bees we actually show there is some useful purpose to having such favorite colors. These innate sensory biases seem to play an important role in helping naïve animals to find food.”

Source: The Adaptive Significance of Sensory Bias in a Foraging Context: Floral Colour Preferences in the Bumblebee Bombus terrestris, Raine NE, Chittka L (2007)"

When I add new plants to our garden, they will be purple. When visiting the garden at Monticello once, huge Bumblebees were so busy collecting nectar they did not mind my observation. It was a thrill to witness their loading up on nectar or pollen. I admire their ambition to complete their work "while the sun shines."

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